Grower Culture

Welcome to Grimes Culture & Grower Tips Resource Center. We extend our gratitude to the Universities, Grower Industry Advocate Groups, and Suppliers for their contributions to this library.
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Click for a list of helpful grower charts for fertilizer, pesticides, etc.. Plus see the new USDA Zone maps.

annuals

Annuals

Culture on common annuals in convenient pdf formats.
Includes both seed and vegetative items.

Perennial Culture

Perennials
Helpful culture on most perennials for seed, cutting, or bareroot.

herb culture

Vegetables
Get what you need to grow great outdoor vegetable garden plants. Culture + Tips for both grower + home gardener.

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Herbs
Get what you need to grow great outdoor herbs. Culture + Tips for both grower + home gardener.

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Featured Grower Tip*

*Used with permission from Syngenta Flowers
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Propagation Soil Management for Spring Crops

By FHG Technical Services

Regardless of propagation method, by seed or by cuttings (vegetative propagation), proper management of the growing medium is one of the keys to successful spring crops.

Seed Propagation
Germination mixes should be:

Free of sticks and other debris
Free of weed seed and disease organisms
Lightweight and fine textured
Physical properties test should reflect a 10-12% air-filled porosity
Low in nutrients - EC should be less than 1.0 mS/cm (saturated media extract)*
Managed to maintain pH of 5.5-5.8*

During Seedling Germination

Maintain soil temperature at 68-86°F*
Cover seeds if required*
Use acid treatments to adjust water alkalinity to a 60-100 ppm bicarbonate level if necessary
Fafard® Germination Mix and Fafard Young Plant Mix are made with sphagnum peat, fine perlite and vermiculite. Fafard PP Mix is made with sphagnum peat and fine perlite and Fafard Plug Mix #1, is a germination mix made with 100% sphagnum peat.

Vegetative Propagation
Fafard growing media 1P Mix, 2 Mix and 2P Mix are recommended.

For vegetative propagation

Mix air-filled porosity should be at least in the 12-18% range
Maintain pH at 5.5-6.0 and EC below 1.0 mS/cm (SME)
Fertilize as soon as the plants come out of mist in anticipation of transplanting
Use bottom heat (68-77° F soil temperature)
Time mist to keep humidity high and the substrate moist. Once roots form, the misting intervals and duration should be reduced to avoid an over-saturated condition.
The incorporation of biofungicides or a controlled-release fertilizer, like Osmocote® Start, can encourage faster rooting and reduced crop time

* Check the culture sheets for each crop to confirm details regarding EC, pH, temperature and more.

Osmocote® is a registered trademark of Everris International BV, its affiliates, or partners.

Tips for Growth Management of Key Vegetative Spring Crops

By Karl Trellinger, Syngenta Technical Services Representative

Growth management of vegetative spring crops starts with using proper temperature management whenever possible after plants are well established. For cool morning DIP, start lowering temperature to 50° F an hour before sunrise and maintain for two to three hours. Petunias grow best when temperature is between 65 and 75°F during the day and 55 and 60°F at night. They can thrive in a colder environment, but this may delay flowering. For geraniums, verbenas, calibrachoas, and lobelias, 70 – 75° F day and 60 – 65° F night temperatures are ideal after plants are established.

Be conservative in regard to applying plant growth regulators, especially if you use new products or grow new varieties. Early growth regulation, proper fertilization (including periodic media testing) and high light conditions are essential for great quality.

When applying drenches of Bonzi® plant growth regulator, be sure to use consistent volumes and crop specific rates. Geraniums, especially Caliente®, are very sensitive to Bonzi.

Geraniums

Pinch: Pinching is only needed on vigorous ivy geraniums, Blizzard® Cascades and Compact Cascades.

Plant Growth Regulators (PGR): Early PGR sprays are essential for high-quality geraniums. For more compact varieties like Tango®, compact ivies and Caliente®, a spray of Florel® growth regulator at 350 parts per million (ppm) two weeks after planting, followed by a Cycocel® growth regulator spray at 750 ppm to 1,000 ppm should work well. For vigorous ivies like Cascades, Blizzard and Calliope®, Florel sprays at 350 ppm two and three weeks after planting, followed by sprays of Bonzi at 2.5 ppm or Cycocel (750ppm – 1,000 ppm) plus B-Nine® growth regulator (1,000 – 1,500 ppm) are recommended.

To slow down the growth or hold vigorous geraniums like Rocky Mountain™ or Calliope, drench with Bonzi a few weeks before finishing at 0.1 ppm. Make sure the Bonzi does not drip into the crops grown below, if you apply it to hanging baskets. Do not drench Caliente with Bonzi.

Verbenas

Pinch: One pinch is needed on all verbenas, ideally in propagation. Trailing verbenas growing in gallons, baskets and larger containers should receive a second pinch. The second pinch can occur in propagation if rooting in a large jumbo plug or after transplant of the rooted cutting.

Plant Growth Regulators: Spray with 2,500 to 3,500 ppm B-Nine or 5 to 15 ppm Sumagic® growth regulator to keep plants in check. The key to achieving well-rounded and compact plants without stretching is a drench with Bonzi at 2 to 3 ppm three to four weeks before finishing. Some growers spray Florel at 350 to 500 ppm early on to improve branching or to substitute for a second pinch.

Petunias

Pinch: Generally only one pinch is needed for most pot sizes. Extra-large pots or baskets can be pinched twice. Use a viricide such as Virkon®-S, RelyOn™ or Trisodium phosphate (TSP) when pinching or trimming after at least every variety.

Plant Growth Regulators: An early application of Florel at 350 to 500 ppm can be used to enhance branching on petunias. To keep the plant size in check, use sprays of B-Nine at 2,500 to 3,500 ppm or Sumagic 15 – 20 ppm. Bonzi drenches at 1 – 3 ppm also work nicely mid-season. Small-flowered Picnic™ varieties generally only need a Bonzi drench at 1 ppm, while more vigorous Whispers™ and Sanguna® varieties typically require 2 – 3 ppm.

Lobelias

Pinch: One pinch, ideally done in propagation, is enough for small and midsize pots. Trailing types will benefit from a second pinch a few weeks after transplant. The second pinch is not as crucial for Techno® Heat Upright types. When pinching, use excellent sanitation, including viricides like Virkon-S, RelyOn or Trisodium phosphate (TSP).

Plant Growth Regulators: Spray with 2,500 ppm B-Nine or 5 to 10 ppm Sumagic to keep growth under control. Bonzi drenches at 1 ppm work well three to five weeks before sale.

Calibrachoas

Pinch: 4.5-inch or quart containers require one pinch (during propagation) while gallon containers or baskets require one in propagation and one after planting. When growing baskets, trimming the branches once they grow over the edge of the baskets results in the most uniform and even plants. Use a viricide such as Virkon-S, RelyOn or Trisodium phosphate (TSP) when pinching or trimming after at least every variety. An early spray of Florel at 350 to 500 ppm can be used to enhance branching or in place of the second pinch.

Plant Growth Regulators: Spray with 2,500 – 5,000 ppm B-Nine, 10 – 20 ppm Sumagic or 5 – 10 ppm Topflor™. The key to achieving well rounded and compact plants without stretching is a drench with Bonzi three to four weeks before finishing. A drench with 1 ppm Bonzi could be enough for compact varieties like Callie® Rose or Callie Light Blue while 3 ppm might be best for vigorous varieties like Callie Bright Red or Callie Star Rose.

©2012 Syngenta. Important: Always read and follow label instructions before buying or using Syngenta products. The instructions contain important conditions of sale, including limitations of warranty and remedy. Caliente®, Calliope®, Blizzard®, Bonzi®, Callie®, Picnic™, Rocky Mountain™, Sanguna®, Tango®, Techno®, Whispers™, and the Syngenta logo are trademarks of a Syngenta Group Company. RelyOn™ and Virkon®-S are trademarks of E. I. du Pont de Nemours and Company or its affiliates. B-Nine® is a registered trademark of Chemtura Corporation. Florel® is a registered trademark of Monterey Lawn and Garden Products, Inc. Sumagic® is a registered trademark of Valent U.S.A. Corporation. Topflor™ is a trademark of SePRO Corporation. Cycocel® is a registered trademark of OHP, Inc.

Direct Sowing Vegetable Seeds

By Ken Harr, Technical Services, Syngenta Flowers

Traditionally, in a bedding plant production plan for greenhouses, vegetable seeds are seeded in plug trays, typically in 288's, 128's and 144's, then transplanted into their finished containers. However, in continuing efforts to maximize efficiencies, more growers are looking for ways to direct sow vegetables into their final containers to lessen the effects of transplant, labor and the time it can take to move and space them. Additionally, there are some distinct advantages to direct sowing large-seed crops such as squash, melons and cucumbers because less transplant shock will be incurred. For example, if distress to the root system is minimized, the plants will become established in the garden faster.

Crop Time

The ideal crop time for direct-sown vegetables will depend on both the crop and the container size. Generally, larger containers will allow for larger, more mature transplants. Compared to smaller containers, it has been observed that transplants grown in larger volumes of soil result in higher and earlier yields. Growers who choose to direct sow vegetable seeds must adjust their growing practices and schedules for different crop species and container sizes.

Table 1.

Crop

Container size

Crop time

Tomato Better Bush

606, 4", 10"

4 - 6 weeks

Pepper Crusader

606, 4", 10"

4 - 6 weeks

Zucchini Golden Dawn III

4", 10"

3 - 5 weeks

Watermelon Sangria

4"

3 weeks

Broccoli Concord

606, 4"

5 - 6 weeks

 

Temperature

When germinating and growing vegetable plants, temperature is critical for producing top-quality crops. Optimum temperatures are listed in Table 2.

Table 2.

Crop

Germination Temp

Days to Germination

Growing Day Temp

Growing Night Temp

Tomato

70 - 74°F

3 - 4 days

65 - 70°F

55 - 64°F

Pepper

72 - 76°F

4 - 6 days

65 - 70°F

62 - 66°F

Zucchini

72 - 76°F

2 - 3 days

70 - 74°F

55 - 64°F

Watermelon

72 - 76°F

2 - 3 days

70 - 74°F

55 - 64°F

Broccoli

65 - 72°F

2 - 3 days

55 - 62°F

52 - 62°F

 

Finishing

In finishing vegetable crops, hardening-off or toning the plants is important to ensure top-quality plants at retail. A few ways to help tone the plants and acclimate them for retails displays include lowering the greenhouse temperatures, lowering overhead air circulation and moving plants outside.

Vegetative Annual Disease Management

By Jane Trolinger, Ph.D., Syngenta Flowers Technical Services

Vegetative annual crops can be affected during production by several different diseases, some of which can be devastating. Recently, two types of pathogens have been problematic for calibrachoa, New Guinea impatiens, petunia and verbena: Botrytis, an ubiquitous fungus known as gray mold; and the tospoviruses, Impatiens Necrotic Spot Virus ("INSV") and Tomato Spotted Wilt Virus ("TSWV"). Here are some tips for managing Botrytis and tospoviruses in the greenhouse. To prevent Botrytis:

  • Remove and discard severely affected plants and clean diseased plant parts (e.g., senescing leaves) from healthy plants. Bag and remove from the greenhouse.
  • Practice thorough sanitation in the greenhouse, especially debris removal from below the bench and aisles, and daily garbage can removal and cleaning. This will ensure Botrytis is not sporulating on any plant tissues or debris and prevent it from spreading to otherwise healthy plants.
  • Avoid injury to plants.
  • Avoid excess nitrogen.
  • Prevent high humidity conditions by providing sufficient plant spacing and air circulation, and by reducing overhead watering. Botrytis spores need a film of water to germinate, so keeping the leaves as dry as possible reduces the chances of Botrytis being able to thrive.
  • Use appropriate fungicides. Please note that ignoring cultural controls for Botrytis and depending solely on fungicide control is not a good idea. For the most effective control, first manipulate environmental conditions to be unfavorable to Botrytis, and then use appropriate fungicides.
  • Some fungicides that are effective for controlling Botrytis include: fungicide (chlorothalonil), fungicide (fludioxonil), OHP 26 GT®-0 fungicide (iprodione), Decree® fungicide (fenhexamid), fungicide (azoxystrobin) and fungicide (cyprodinil and fludioxonil). Please be aware that resistance to iprodione and, more recently, fenhexamid, has been reported.

 

Impatiens necrotic spot virus ("INSV") and tomato spotted wilt virus ("TSWV") are transmitted by western flower thrips ("WFT"), so the best way to control these viruses is to control the thrips, which are considered one of the most serious pests on ornamental crops. In addition to vectoring the tospoviruses, WFT damage plants directly by feeding. Generally, INSV is a more frequent problem in greenhouses than TSWV. Key information to prevent tospoviruses:

  • Thrips can pick up the virus only as immatures, but immature thrips cannot transmit tospoviruses. Thrips can transmit the virus only as adults, but adult thrips cannot acquire tospoviruses. So, tospoviruses are transmitted by thrips only when immature thrips acquire the virus, pupate and emerge as viruliferous adults.
  • All stages of thrips must be controlled to control tospoviruses. Control of thrips pupae in the growing medium is best accomplished by drench applications.
  • Tospoviruses are actually difficult to mechanically transmit. It's highly unlikely that tospoviruses will spread by normal handling of plants in greenhouses. The risk of spreading tospoviruses is higher on cutting knives or pruning equipment because sap transmission is possible.

 

In a greenhouse, all symptomatic plants should be removed and/or destroyed, and daily scouting should be conducted to remove any plants with further development of symptoms. This must be accomplished while spraying rigorously to control all stages of WFT. Other diseases of the vegetative annuals are:

  • Calibrachoa: Phytophthora crown and stem rot and Tobacco Mosaic Virus ("TMV")
  • New Guinea Impatiens: Alternaria leaf spot, Rhizoctonia web blight, Septoria and Pseudomonas leaf spot
  • Petunia: Phytophthora crown rot, Powdery mildew, Rhizoctonia web blight, Sclerotinia crown rot and Tobacco Mosaic Virus ("TMV")
  • Verbena: Alternaria, Cercospora and Corynespora leaf spots, Powdery mildew, Rhizoctonia root and crown rot, Thielaviopsis root rot, Potyvirus (Poty) and Bidens Mottle Virus ("BiMoV")

 

Scout your crops regularly for problems and get a head start on disease issues by dealing with them from the start. It is much better to prevent problems and keep them under control rather than suffer the losses they can cause.

Improve Performance of Bedding Plants at Retail and for the Consumer

By Karl Trellinger, Syngenta Technical Services

The difference in retail performance between a soft, stretchy plant and a well-toned, properly fertilized and acclimated plant is tremendous. While a soft, under-fertilized plant may barely make it through the weekend at retail, a well-fertilized, compact plant that has been hardened-off can perform well for the consumer, after four-to-six days in a normal retail environment. Plants with good shelf life should have the following characteristics:

  • Long-lasting flowers
  • Colored buds with the ability to readily open at store level
  • High tolerance to cold, wind, heat and drought
  • Quick rebound from shipping, handling and adverse weather conditions
  • Compact at the store and grows readily after planting


Stretchy, soft plants are prone to damage during handling and exposure to wind at retail


Well-grown, properly growth-regulated and fertilized geraniums ensure quick sell through and great performance for the consumer

Below are the key aspects during production that can influence post-harvest quality:

  • Fertilization: It is crucial to properly fertilize the plants until they get shipped to prevent yellow foliage and reduced flower power for the consumer. For the last two-to-three weeks, switch to a low phosphorus and low ammonium-nitrogen fertilizer like 13-2-13, 14-0-14, 15-3-20, or similar blends to avoid lush and stretchy growth. Unless a Cal-Mag™ fertilizer is being used, provide additional magnesium sulfate weekly or bi-weekly depending on the crop to avoid interveinal chlorosis, which often can appear at the end of the crop.

 

For best consumer performance, include (depending on species) a low-to-medium rate, five-to-six or seven-to-eight month controlled release fertilizer.

  • Media: Select well-aerated media with adequate water-holding capacity, and monitor nutrient levels, EC, and pH bi-weekly. If plants are shipped to retail with high EC levels in the media, roots could burn if the media dries out at retail.
  • Light/Temperature: Provide proper spacing to avoid diseases, lower leaf-yellowing and stretchy growth. To acclimate plants to retail and consumer environments, lower the temperatures for the last three weeks of production while reducing watering frequency.
  • Moisture Management: Especially under cloudy and rainy conditions, keep plants dryer than usual. This also helps in keeping the humidity in the greenhouse as low as possible. Make sure that greenhouses are properly ventilated with good horizontal airflow and dehumidification.
  • Growth Regulation: Adequate plant growth regulation is a great tool to tone the plant, but should not be used to cover up insufficient feeding, overwatering or insufficient light conditions. Always apply plant growth regulators (PGRs) at low rates in order to adjust to changing climate conditions and avoid over-application. Avoid high-rate PGR drenches at the end of production that might result in stunting and poor growth/flowering for the end consumer. Most spring annuals can benefit from Bonzi® plant growth regulator drench three-to-four weeks before shipping to avoid stretch.


Bonzi drenches three-to-four weeks before shipping result in compact, sturdy plants that are less susceptible to damage during shipping and at retail

  • Before Shipping: If shipping long distances and/or weather conditions are poor, remove spent blooms, old foliage and spray with a fungicide, such as Palladium® fungicide, to protect against foliar leaf spots and Botrytis. Avoid fungicides that leave a residue or can burn flowers.
  • Shipping Temperatures: A shipping temperature of 42°F works for most crops. Cold-sensitive crops like vincas, begonias, salvias, New Guinea impatiens, sweet potato vines and others should be shipped at 55°F.


Ensure Hard Work in Production Pays Off at Retail

Place various species in sun or shade depending on their needs. It is crucial that store personnel are properly trained and that they take the time to check on plants and water them before they get too dry, especially under hot and windy conditions. Plants should be displayed where they can be irrigated easily and thoroughly.

Perennials: Summer vs. Late Winter Transplanting Options

By FHG Technical Services

Large perennial growers transplant nearly year-round to produce crops that meet their market needs. For growers who choose the summer transplant option, the cost savings on liners and balancing the workload makes up for additional costs during the long growing cycle. Winter transplanting offers timing predictability at a high yield. Transplanting perennials in May adds product depth during garden mum season, a competitive advantage compared to growers who only offer mums, pansies, and ornamental cabbage or kale.

Summer Transplanting

The goal for summer transplanting is to have well-rooted plants that are prepared to go dormant and survive the winter. For early spring-blooming perennials, vernalization is required to induce flowering. This is achieved naturally when plants are transplanted in late summer and grown through the winter. Aubrieta Audrey, Aurinia Summit and Iberis Tahoe are three gems to offer for summer transplanting.


Aurinia Summit


Iberis Tahoe

Summer transplanting can save money on upfront costs. Smaller liners or bare root plants (number two grade) are less expensive than larger plants and are ideal for summer transplanting. Younger and smaller plants cost less but add time, effort and cost to the overall crop. The longer the crop cycle, the more opportunities there are for disease and insect problems. Overwintering perennials is rarely 100 percent successful. Fafard® 3B Mix (middle-weight) with aged pine bark is an excellent, well-drained growing media to help carry perennials through the winter. Fungicide-preventive treatments such as Hurricane® WDG fungicide for root rot pathogens are required.

Late Winter Transplanting

Many growers opt to transplant from February to April. When transplanted on time and grown slowly in a heated greenhouse (50 to 60°F days and 45 to 50°F nights), perennials can be featured in advertisements targeting particular sale dates from May through June. For late spring and summer sales, "first year flowering" perennials are good choices. Some examples are Digitalis Camelot, Aquilegia Origami and Lupinus Camelot for one-quart and one-gallon pots. Generally, crop timing for a one-gallon pot transplanted from a 72-size liner ranges from 10 to 12 weeks in February and six to eight weeks in April.

Preventive fungicides are necessary in late winter transplanting, but only one or two applications may be needed during the crop cycle. Subdue MAXX® fungicide tank-mixed with Medallion® fungicide will provide excellent root rot and foliar disease control.


Digitalis Cameo Rose


Aquilegia Origami

Bonus: May Transplanting

Growers can expand their offering during garden mum season by transplanting perennials in May or early June. Ideally, selected crops are "first year flowering" and will bloom late August through September or early October. Salvia Merleau®, EchinaceaPrairie Splendor and Gaillardia Granada will easily complement Yoder® Garden Mum deliveries. They are also propagated from seed, so input costs will be lower.

Starting Your Natural Season Garden Mums

By Mark Smith, Syngenta Technical Services

Planting

• Growing medium should retain adequate water after irrigation but also drain sufficiently to provide aeration during rainy weather. A good target is 12 to 18 percent air-filled pore space. The pH range should be 5.8 to 6.2. Peat based mixes or heavier bark based mixes are commonly used.
• Plant your cuttings as soon as they arrive or as soon as they are rooted (if you root your own) to prevent stress which can stall initial growth. Plant just deep enough to cover the root ball or a bit deeper if using Oasis® liners.
• Always water-in cuttings with a complete N-P-K fertilizer solution containing full-strength liquid feed immediately after planting.
• Plant outdoor crops in mid to late June after the night temperatures are above 60°F. This will allow for more growth than planting in late May, when premature bud initiation from cold night temperatures could occur.
• Make sure the pots are adequately spaced to prevent plants from touching, which will allow varieties to reach their full potential.

Pinching

• Pinching is no longer required for producing natural season garden mums.
• If you still pinch your cuttings, leave a few unpinched this year and see how they turn out - you will likely be surprised.

Florel

• If you plan to use Florel™ plant growth regulator with your garden mums this year as insurance against budding, put the first spray on the cuttings while in propagation or one to three days after planting. Do not spray Florel on stressed cuttings.
• Rates of 350 to 500 ppm are commonly used with spraying frequency of every 10 to 14 days.
• The Florel effect is reduced on shoots that have already initiated buds, so it is important to start Florel early to maintain flowering uniformity of finished plants.

Irrigation

• Drip irrigation creates a better environment for the plants and can be designed to significantly reduce water and fertilizer waste.
• Plants should not be allowed to wilt during the first third of the crop as that can have negative effects on finished plant size. During the final phase, restricting water can be used to tone the plant and prevent overgrowth.

Fertilizer

• Growers using water soluble fertilizer (WSF) often use an ammonium based fertilizer for the first two weeks and then switch to a nitrate based fertilizer. Electrical conductivity (EC) values of 2.0-3.5 mS/cm (SME extract) or 2.5-4.5 mS/cm (pour-through extract) should be maintained.
• Growers should regularly monitor growing medium EC values. Low or decreasing EC values would indicate the need for supplemental fertility.
• The WSF rate can be reduced once the plant body has been built and/or once there is a need to irrigate more than once a day.
• It is important to re-feed your pots after rain to get fertilizer back in the media and available for the plants.
• Lower N-P-K rates than traditionally used for mums are possible if extra micronutrients are added to maintain their level. Similar to feeding at a 250 ppm N level with a WSF that contained micros.
• If you are using controlled release fertilizer (CRF) instead of liquid feed, be sure it includes micronutrients. The recommended application rates vary by product and are listed on the labels. High application rates are required to provide adequate nutrition. If at all possible, water-in the plants with a WSF to boost initial fertility.

Cool Season Seed Crops: The Warm-Up Band for Peak Spring Performance

By Syngenta Technical Services

Beginning in the quiet of fall and winter, cool season crops keep growers in tune and serve an important financial purpose: bringing in sales dollars from February through April. Because cool season crops typically have longer production cycles, growing practices early in production can have a long-lasting effect. A production planning mistake, such as a late seed or plug order, or growing error, such as a fertilizer injector not functioning effectively, can keep growers scrambling to catch up for weeks. Conversely, a well-conceived plan solidly executed can successfully kick off early spring, setting the stage for the peak bedding plant season and keeping retailers eager for the next performance.

General cool season tips

Long crop cycles over the winter months are predictably troublesome. Irrigation and fertilization become especially important when days are dark, light levels are low and humidity can build. Every day should begin with good, fresh air flow and sound moisture management; that is, appropriate volume, type and timing of irrigations. A well-drained potting medium is required for versatile moisture management. Peat-based media with 20-30 percent perlite is often used with great success, or if choosing a bark-based mix, it should contain at least 35-45 percent aged or composted bark.

Use this long production cycle to practice and perfect routine scouting programs. Stock a tool chest of plant protection products to control Botrytis, leaf spots and root rots when necessary.Medallion® fungicide, Micora™ fungicide, Heritage® fungicide, Palladium™ fungicide andSubdue Maxx® fungicide are versatile, cost-effective products to have on hand. They can protect plants for weeks depending on the disease and timing of application. Aphids and spider mites are not uncommon in cool season crops, although they are slower to develop a large population at low temperatures. It may only take one warm period, however, and these pests will seize the opportunity to feed on the plants and multiply exponentially! IncludeFlagship® insecticide, Avid®insecticide andEndeavor® insecticide in the tool chest, and use them appropriately on target pests. Follow all label directions, and if unfamiliar with their compatibility on cool season crops, test a small block before applying to the entire crop.

Finishing your Garden Mums (Tech Tip )

By Mark Smith, Syngenta Technical Services

As you now work to close out the season and send flowering plants to market, here are some tips to help finish your garden mum crop.

Water

Water can be the best growth regulator for a garden mum crop. If plants are larger than desired, reduce your irrigation frequency so a light wilt appears before irrigating. This will reduce growth and speed up flowering. If you need to increase size, keeping plants more evenly moist will add volume even after you start to see bud set. It is important to note that the extremes can still cause damage so avoid excessive dry down or overly wet pots, which can lead to root damage.

Fertilizer

Fertilizer can help drive plant growth especially early in the crop. Ammonium sources of nitrogen are often used to keep plants actively growing. This is helpful at the beginning of the crop, but not wanted at the end of the crop. Nitrate-based fertilizers at the end of the crop will create stronger plants and not interfere with the natural flower process. An overall reduction in the fertilizer rate at the end of the crop can also reduce excess growth and speed up flowering.

Growth Regulation

Many growers use growth retardants to tone and maintain proper plant size. B-Nine® plant growth regulator is often used at the beginning of the crop to reduce internodes and develop a strong plant base. Once flower buds have started, B-Nine sprays can delay flowering. Bonzi® plant growth regulator drenches at low rates are ideal at the end of the crop to maintain size without affecting flower timing.

Pest and Diseases

Scouting the crop is still needed to prevent pests and disease problems. Two-spotted spider mites and caterpillars may be within the plant canopy. Check leaves for evidence of these pests and feeding damage. Watch for moth activity in the field, as an indicator of young worms in the future. It is important to monitor thrips populations, particularly when flower buds begin to crack color. Sprays of Avid® insecticide and Conserve® insecticide can be applied at this stage.

Poinsettia Propagation

By Harvey Lang, Syngenta Technical Services

Sanitation

To reduce the chance of fungal and bacterial infections, it is important that the propagation area is cleaned and sanitized before cuttings arrive. Weeds should be removed and algae-infected areas scrubbed and cleaned. All benches and floors should be thoroughly disinfected using a greenhouse disinfectant containing quaternary ammonium.

Make sure sanitation protocols are in place as the greenhouse is prepared to receive cuttings. Foot baths containing disinfectant should be placed at all entrance ways into the propagation area. These baths should be renewed daily with fresh disinfectant. Managers and workers should wash hands with a disinfectant or anti-bacterial soap before entering the propagation area after lunch and breaks.

Upon Arrival

Make sure that the rooting media is laid out on clean benches several hours (or the day before) cuttings arrive. For direct-stick programs and those where cuttings are handled in sticking lines, make sure that all workers are present and that equipment is working correctly. Workers should be prepared for the day's shipment.

Store opened boxes at 50-55°F/10°C for no more than 24 hours and prevent cutting dehydration during storage (ideally 90 percent relative humidity in coolers). Do not open up the individual bags of cuttings as this helps maintain high humidity around the cuttings.

Stick the cuttings immediately if possible. For relatively large shipments, pull out only enough cuttings for each worker to stick within an hour or so before replenishing with another fresh box of cuttings from the cooler. If cuttings cannot be stored in a cooler, try to store in the coolest area of the facility and monitor closely for humidity and cutting water loss. Some growers without cooler space also lay opened bags on the propagation bench and begin misting. Do not leave opened, un-stuck cuttings on the propagation bench for more than a few hours or they can become twisted and curled.

Temperatures

Warm temperatures and humid conditions are needed for successful poinsettia propagation. Bottom heat is very helpful, especially in northern areas where night temperatures are relatively cool. Try to maintain temperatures between 73°-75°F/23°-24°C in the media until the cuttings are fully rooted. Poinsettias are propagated during the warm summer months so greenhouse day temperatures will normally be significantly higher than night temperatures and constant temperatures are more difficult to hold. If at all possible, try to avoid night temperatures below 70°F and day temperatures above 85°F the first two weeks of rooting.

After good root development, temperature and humidity can be reduced and the cuttings acclimated to higher light intensities. Ideal media temperatures are between 70°-72°F/21°-22°C with air temperatures varying based on climatic conditions. Again, try to avoid low night temperatures and high day temperatures as cuttings are finishing up the propagation process.

Most varieties are generally well rooted in four weeks using these recommended temperatures.

Rooting Hormones

Many growers feel they do not need to use rooting hormones if they have good bottom heat and good healthy cuttings. Syngenta Flowers suggests that rooting hormones slightly reduce rooting time and even out rooting along the bench. Some growers use powdered material while others use liquid types (e.g., Dip'N Grow® liquid rooting concentrate or Rhizopon® indole butyric acid (IBA) rooting solution). When applying, use a 0.1-0.2 percent IBA or combination IBA + napthelene acetic acid (NAA) applied only at the base of the cutting. Trials are recommended before using new rooting compounds or concentrations.

Relative Humidity

High relative humidity, especially for the first five days, is critical to reduce stress on the cuttings and to help get them out of a wilted and flagged stage. Many growers are now using fog systems to maintain humidity above 90 percent in the poinsettia propagation area. High humidity should be combined with heavy shade and minimal air movement. This helps reduce the amount of misting that is needed and reduces the chances of Botrytis and other diseases.

Misting

Use a fine mist, applying enough to wet the foliage but not to the point of drip. Short and more frequent bursts of mist are better than long mist cycles with less frequency. Adjust mist daily according to weather and the condition of cuttings. Avoid standing water on the leaves if possible. Puddles of standing water on young leaves for lengthy periods of time can cause tissue breakdown and eventual disease.

It will take a day or two for the unrooted cuttings to become completely rehydrated and turgid after sticking. Avoid excess air movement across the leaf surface, especially in the first week. Mist so that the leaves do not roll --- you do not want to see severely flagged poinsettia cuttings, especially after rehydration and sticking. Severely flagged cuttings in the early morning indicate that inadequate mist was applied during the night. Running cuttings too dry causes leaf scorch, delays in rooting, and possible leaf loss. If the cuttings look stressed on sunny days, shade is recommended rather than additional mist.

Use a spreader-sticker (like Capsil® 30 surfactant, at a rate of 2-4 ounces/100 gallons) on cuttings as soon as possible after sticking to reduce leaf surface tension and improve moisture uptake into the leaves. Capsil 30 causes the water to spread more evenly across the leaf surface. Many growers combine the Capsil 30 with an appropriate fungicide for Botrytis control. Reapply whenever water droplets are forming on the leaves and the moisture is not evenly distributed across the leaf surface. Capsil 30 at similar rates above can also be used as a pre-plant spray or dip on cuttings. Avoid dipping the cut end if possible when using pre-plant dips.

Shade

Provide heavy shading until the cuttings develop a good callus. Try to keep maximum light levels between 900-1,100 foot-candles (4-6 mols/day). It is critical to pull enough shade under bright sunny conditions to help reduce stress and heat load on the plants. This will also help reduce the amount of misting needed which leads to less Botrytis and bleached foliage.

Once roots begin to form (10-12 days or so for most varieties), light levels can be gradually increased to 1500-2,000 foot-candles (8-10 mols/day) as long as misting does not have to be significantly increased. When the plants are well rooted (approximately three weeks), light intensities can increase to 3,500 foot candles (15-18 mols/day).

Fertilizer

Start the fertilization program early. Poinsettias have relatively long requirements for misting during propagation and leaves can get heavily leached of nutrients, especially medium-green-leaf varieties. Many times the first leaves that develop on a rooted cutting are yellowish-green caused by lack of nutrients within the plant.

The first feeding to the media can be done 9-10 days after sticking and after root initials have formed and early rooting has begun. Growers should start with 100 ppm N and K. Once the roots begin to form, rates can be increased to 150 ppm N and K and eventually up to 200 ppm N and K if needed. Some growers sub-irrigate the rooted cuttings to avoid overhead fertilizer burn; however, be aware of the potential disease spread along the bench using such setups. We have seen a few cases of Rhizoctonia fungi moving along the bench and infecting cuttings in sub-irrigation troughs.

Finishing all overhead fertilization by 9:30 a.m. helps prevent foliage burn. It is also always wise to rinse the fertilizer off with plain water before the fertilizer solution dries on the leaves. Stay away from high phosphorus concentrations applied over the foliage, as this can stunt the young leaves if the foliage is not rinsed off afterwards with clean water. Use primarily calcium nitrate + potassium nitrate formulations during propagation, such as 15-0-15, 14-0-14, or 13-2-13. An occasional 20-10-20 or 15-15-15 type can be used if the plants need to be greened up before moving out of the propagation area.

Poinsettia Finishing Tips: The Last Three Weeks

By Karl Trellinger, Syngenta Technical Services

Temperature

The ideal temperature to finish poinsettias depends on the variety, root system and humidity in the greenhouse. Medium-green-leaf varieties such as Whitestar™, Maren™, etc. should not be finished at night temperatures cooler than 65oF. Dark-leaf varieties generally can be finished cooler at 60-62oF nights. Some energy-efficient varieties with large bracts, such asTitan™, Early Orion™, Orion™, Cortez™ Early Red and Mira™ Red, can be finished at 58oF nights, as long as the root system is good and relative humidity is below 75 percent. Keep average daily temperatures no lower than 62oF under these conditions. It is critical to provide even heat distribution, moisture level and good air flow to avoid Botrytis infection.

Cold Finishing

Syngenta Flowers has conducted extensive trials across North America with many varieties to better understand the effects of cold growing and finishing on growth and flowering. For more information on cool growing and finishing, review our document on Energy Efficient Poinsettia Production.

Light

Light levels of 3,000 foot candles (approximately 13-14 moles/day) are ideal up to three weeks prior to shipping. Levels can be lowered for the last two weeks to 2,000-2,500 foot candles (10-11 moles/day). It is important for the white and pink varieties to have lower light conditions during finishing to achieve the best coloring. Many red varieties can also bleach and fade under extremely high light levels the last two weeks of bract development.

Fertilization

Steadily reduce fertilization to 80-100 ppm Nitrogen, starting approximately three weeks before finishing. Irrigate with clear water one or two times prior to shipping to remove excess salts in the growing media. This will minimize the chance of bract edge burn and root injury once the crop leaves production.

Roots

Under cool and humid conditions, saturated media can lead to late season root infections by Pythium spp., which can cause losses during production, retail or at the consumer level. Check the roots frequently during the final three weeks of production and apply a fungicide drench for Pythium if necessary. Depending on which products have been used prior, drench with fungicides such as Subdue Maxx®, Truban®, Terrazole® (restricted in CA) or Segway®.

Gibberellic Acid (GA)

If the plants are too short, the bracts too small or if the coloring is behind, a 2-3 ppm Fascination® plant growth regulator spray plus CapSil® spray adjuvant is recommended. White varieties such as Whitestar, Cortez White or Mars™ White benefit from a spray about 14 days before shipping, which generally results in a better white color, earlier coloring by three-to-five days and larger bracts. The spray must be applied evenly to avoid unbalanced bract expansion. It is important to keep the average daily temperature above 65oF. If needed, drench with Bonzi® plant growth regulator at 0.5-1 ppm to avoid late season stretch or to hold plants that are not yet sold. Test trials should be conducted to determine the appropriate rate.

 

Whitestar. Plant on the left untreated, plant on the
right had been sprayed with 2ppm Fascination two
weeks prior. Notice larger bracts and better white
color on the treated plant.

Mars Red. Ideal bract development stage for a late
season Bonzi drench about two weeks before finishing.

Late-season Bonzi drenches

For traditional late-season growth control, drench with Bonzi using 0.25-0.5 ppm (0.75-1.5 oz/100 gal) for production in northern areas or 0.5-1 ppm (1.5-3 oz/100 gal) in the South. This can be done when the plants are about one inch below the desired height and/or one-to-two weeks (up to three weeks in the south) before shipping. Bonzi should not be drenched at these rates before three bract leaves show full color; otherwise the bract size may be reduced significantly. This treatment can be repeated if the effect is not strong enough. At these low rates, Bonzi drenches can be done through the watering system. The plants should be watered the day prior to treating with Bonzi. It is also important to keep drench volumes consistent from pot to pot to ensure consistent results throughout the crop. The late-season Bonzi drench has the added benefit of intensifying bract color and holding cyathia longer, resulting in increased post-harvest performance. Test trials should be conducted to determine the appropriate rate.

Botrytis

To minimize infections by Botrytis, maintain good air movement and low humidity (heat and vent simultaneously under moist and rainy conditions) especially at the end of the crop. Fungicide applications should be used in rotation, includingPalladium®, Medallion® WDG, Heritage® or Decree® for Botrytis control. Adding CapSil at 3-4 oz/100 gal can improve spray distribution on waxy plant surfaces, reduce residue and enhance performance.

Insect Control

Insect populations are generally low during the final stages of production, though this can vary depending upon the region. If whitefly or thrips levels are still of concern, Avid® insecticide can be used alone or in combination with pyrethroids to control these pests when bracts are in full color.

Preparing for the Cutting Propagation Season

By Jamie Gibson, Syngenta Technical Services

Prior to sticking cuttings in the greenhouse, there are several important tasks in propagation that should be completed to achieve successful rooting:

- Ensure walk-in coolers and refrigerators function correctly before receiving cuttings.
- Properly seal greenhouses to minimize pest and weed seed entrance.
- Maintain excellent sanitation practices in propagation production. Propagation trays and tools should be washed using a quaternary ammonium compound such as MicroBloc® mold treatment spray, Green-shield® disinfectant or Physan 20™ disinfectant.
- Keep floors devoid of debris. Glazing and bench surfaces should be sterilized.
- Eliminate algae. Algae are a food source for shore flies and fungus gnats. ZeroTol® algaecide/fungicide at a 1:100 dilution or STRIP-IT ™ greenhouse cleaner at 4 oz/gal can be used as sprays on benches and floors for algae control.

In addition to the propagation steps above, review the following reminders to prepare for the coming propagation season.

Mist: Bleed all mist heads and plumbing prior to the season to avoid obstructions, which lead to skips and dry pockets. Make sure that mist heads or booms completely cover the bench or floor propagation area sufficiently. A spray adjuvant, such as CapSil®, is recommended to prevent water from beading up on the leaves.

Soil and air temperature: Boilers, heaters and forced air systems should be inspected prior to the propagation season. During the early stages of cutting propagation the soil temperature should be 71 to 73°F. Monitor the root zone temperature with soil thermometers at multiple locations throughout the propagation plot to identify "hot" and "cold" zones.
Cutting propagation environments during the first few stages
of rooting will require temperatures above 65°F.

Rooting hormones: Most herbaceous cuttings will not require a rooting hormone. Hormones are generally not needed with sufficient bottom heat. Talc-based or water soluble hormones (K-IBA) should be on hand if growers are propagating difficult-to-root or semi-woody species.

Media and moisture level: It is important to use a growing medium that offers a good combination of water-holding and aeration properties which meet the rooting needs for specific crops grown. Refer to Syngenta Flowers Tip 1 and Tip 7 for propagation media recommendations. The root medium should be pre-moistened before sticking cuttings to avoid desiccation of the basal portion of the stem cutting. If direct sticking is preferred, watering the pots initially in such a way that only the upper third of the pot is moist and the bottom portion is dry is very important to minimize losses.

Light: The ideal light conditions for the first two weeks after sticking are 2,000 foot candles, although light intensities between 1,500 and 3,000 foot candles are acceptable. Invest in a light meter to measure the light levels, with and without shading materials, at bench level to gain a sense of light quality.

Fertilizer: Use a balanced fertilizer higher in nitrate-nitrogen such as 15-5-15, 13-2-13 or 14-0-14 once cuttings begin to root. Foliar feeding with 50 ppm nitrogen while cuttings are under mist may be appropriate under very cloudy and humid conditions. These conditions may result in reduced leaf transpiration and nutrient uptake from the soil.

Excessive ammoniacal-nitrogen and phosphorus containing
fertilizer applied to rooted cuttings will cause lush growth and
stretch. Low light conditions can also trigger undesired growth.

Plant protection: Methods to reduce disease include proper misting, sufficient spacing, removing infected leaves and good light conditions. Preventive fungicide treatments for common root and stem diseases in propagation include Subdue Maxx®, Daconil® , Heritage®,Palladium®, Decree ® and Chipco® 26019.

Plant growth regulators: A PGR toolbox containing Bonzi®, B-Nine ®, Cycocel® and Florel® can be useful for managing plant size during or at the end of propagation. Use Cycocel or Cycocel and B-Nine tank mix combinations for less vigorous varieties and Bonzi sprays for more vigorous varieties. Florel is effective during the hardening-off stage.

Upon arrival: Unrooted cuttings should be unpacked and stuck immediately to prevent desiccation and injury. If this is not possible, the opened boxes should be placed in a cooler. Use a digital camera to capture any problems that are observed with the cuttings after opening boxes.

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