Growing Vegetable Bedding Plants (Scheduling, Nutrition, Height)

Whether it is a small back yard (or front yard) garden, patio pots or a community garden, vegetable gardening is making a come-back. Food costs have increased and the salmonella and E.Coli scares have made consumers unsure about the food they buy and are focused on healthful lifestyles. As a result, being a “localvore” is in and growing your own is even better. Today’s gardeners have less time than their parents, so are more likely to have smaller gardens. Larger transplants in individual pots, patio pots, trellised plants, mixed planters as well as traditional packs are popular.

Consider adding a few vegetable plants to your spring crop production program using the same enthusiasm for choosing and growing vegetables as you do for flowering plants. Plan to offer old “reliable” varieties, and heirloom varieties along with some new exotic plants and varieties. Whenever possible, select disease resistant varieties to help insure success in the garden.  There are so many choices, from gourmet greens and vegetable amaranth  (popular in Southern Asia, Africa and West Indies) to yellow cherry tomatoes and an assortment of colored peppers and eggplants. To find new varieties see the All American Selection (AAS) Winners website www.all-americaselections.org/ , the National Garden Bureau website www.ngb.org/index.cfm and your favorite seed supply company catalogues.  State University trial results can also help you select varieties that will perform best in your area.  For example, AAS winners for 2009 include a white eggplant ‘Gretel’ that can be harvested in 55 days and grows to three feet tall and wide, great for containers; a personal sized winter acorn squash called ‘Honey Bear’, also for smaller gardens and a melon called ‘Lambkin’ that is sweet and juicy. Create “edible containers”, by combining flowers and vegetables in mixed planters. Swiss chard, ‘Bright Lights’ with pretty colored stems in reds, pink, yellow and orange are easily grown and are great for containers or in the ground.

Starting From Seed

With the exception of a few perennial vegetables, vegetable plants are started from seed. Easy to transplant vegetables that are able to absorb water efficiently and form new roots rapidly include beets, broccoli, cabbage, lettuce and tomatoes. Vegetable plants that are a little more difficult to transplant, do not absorb water as efficiently, but form new roots quickly include cauliflower, eggplant, onion and pepper. Vegetable plants that are difficult to transplant include cucumbers, melons and squash.

Production Schedules

Starting seeds too soon, will result in overgrown plants of poor quality. The following are guidelines for growing vegetable bedding plants. Note the number of weeks from seed to sale for packs. This will vary according to different growing conditions across the country and should serve only as a guide.

(From Tips on Growing Bedding Plants, Ohio Florists Association)

Cole Crops (Cabbage, Broccoli, Brussels sprouts, Cauliflower)

To prevent premature seeding or bolting, avoid exposing transplants to temperatures below 50°F for long periods (week or more). The cold temperature will cause “buttoning” in cauliflower and broccoli. Any stress or check in growth results in a “wirestem” so that they do not get as well established in the garden.

Eggplant

Eggplants are susceptible to chilling injury and should not be grown below 40°F. Any stress or check in growth will result in tough woody stems and transplants that will have a tough time getting started later in the garden.

Tomatoes

Tomato seeds germinate best at 70 to 80°F. As soon as there is any evidence of germination, they should be removed from mist and bottom heat. The ideal root-zone temperature is 77-86°F during the first four weeks of growth and 68 to 77°F during the fifth and sixth weeks. Optimal growing-on day temperatures are 65 to 75°F and minimum night temperatures of 60°F.

Peppers

Note that germination is very slow at lower temperatures.

Vine Crops

Cucurbits do not transplant well, and are best to sown in the final container. After germination, excess plants can be thinned.

General Nutrition Guidelines

Vegetable bedding plants can be grown in soilless potting mixes and fertilized with commonly used fertilizers such as 15-0-15 Dark Weather Feed, 15-15-15, 15-16-17 and 20-10 20 or Cal-Mag 15-5-15.

Soil should be tested each month to adjust the fertilizer program and to prevent problems. The optimum pH range for vegetable bedding plants is 5.5 to 6.5.

While plants are in the plug or seedling stage, use a complete water soluble fertilizer at the rate of 50 – 100 ppm N every time plants are watered and use clear water (no fertilizer) every third watering. Use the lower rate (50 ppm) early and the higher rate (100 ppm) later if the seedlings are to be held in the flat or tray three or more weeks before transplanting. Shortly after transplanting, as plants approach rapid growth, increase the rate to 200 ppm N at every watering, watering with clear water 2 or 3 times in-between each fertilization.

Small, slow-growing plants should receive lower rates or less frequent application until they are well-established. Care should be taken not to over-fertilize vegetable bedding plants because no growth regulators are labeled for use on edible crops.

Nutritional Problems

Early in production, serious nutritional problems are: high soluble salts, trace element toxicities, and ammonium toxicity. Late in production, particularly in cell packs, plants may develop nitrogen deficiency symptoms.

Injury from excess salts seems to be most common shortly after transplanting. Seedlings are much less tolerant than established, rapidly growing bedding plants. Some soilless mixes may contain enough "starter charge" to cause excess salts problems in the first few weeks after transplanting, particularly when a water-soluble fertilizer is also applied. This problem can be aggravated by excessive drying, poor drainage, and uneven watering. Roots of plants should be checked often and regular soil tests conducted to identify and prevent problems. Often nutrient deficiencies and root diseases cause the same symptoms.

 Iron (Fe) and/or manganese (Mn) toxicity can occur in tomato plants. Symptoms appear as numerous small dark spots and mottling of the foliage. The potential sources of excess Fe and Mn are: trace element fertilizers in the mix, water-soluble fertilizers with elevated trace elements levels, and sometimes, the  irrigation water. Low growth medium pH aggravates the problem by increasing Fe and Mn availability. Toxicity can be avoided by keeping the pH in the range of 5.8 – 6.0 and by using fertilizers with lower trace element levels.

Ammonium toxicity is less common than in the past, because most growers currently use water-soluble fertilizers that supply about 50/50 ammonium and nitrate to fertilize plants in soilless media. Tomato, eggplant, and pepper are most sensitive to ammonium nitrogen, but many other vegetable bedding plants can be harmed if ammonium becomes excessive. Too much ammonium during the early spring (February or March) in low light and cool media conditions can be toxic to plants.

Managing Plant Height

Since few growth regulators are registered for vegetable bedding plants, plant height can be managed by adjusting water, temperature and fertilizer levels, or by physically brushing the plants. Research has shown that mechanical stress reduces stem elongation and maintains plant height. Growers can mechanically stress plants by brushing transplants twice daily for 18 days using about 40 strokes back and forth with a sheet of plastic or foam tube suspended from an irrigation boom. This can result in as much as a 30% reduction in stem elongation. Vegetable plants such as tomatoes, eggplants and cucumbers have responded to this method of height control. Note that this technique has damaged some tender plant species such as peppers and could also enhance the spread of disease.

Water stress is another tool to manage plant height. Maintaining plants on the dry side limits cell expansion and plant growth. Close attention is needed to avoid permanent damage such as leaf burn or even plant death.

Withholding nutrients can also be used to prevent stretching. Low phosphorus fertilization is especially effective for tomatoes. If carefully managed, a mild to moderate phosphorus (P) deficiency may result in a desirable reduction in growth with no foliar symptoms of P deficiency.

Organic Production

Using organic production practices for the organic market is another option for growing vegetable plants.  In doing so, plant must be grown according to national organic standards by The U.S. Department of Agriculture. For more information see: http://www.ams.usda.gov/nop/Consumers/brochure.html   

References:

• Pundt L. and T. Smith. 2007 Growing Vegetable Bedding Plants.
  http://www.umass.edu/umext/floriculture/fact_sheets/specific_crops/veg_bedpl.htm
• Tips on Growing Bedding Plants. 1994. Third Edition, The Ohio Florists’ Association

Helpful Websites on Organic Production

• Biernbaum, John. 2006. MSU Organic Greenhouse Transplants; Illinois Organic Conference. http://www.ipm.msu.edu/pdf/Biernbaum-Transplants.pdf
• ATTRA - National Sustainable Agriculture Information Service http://www.attra.org/horticultural.html#Greenhouse
• The National Organic Program Guidelines
  http://www.ams.usda.gov/nop/indexIE.htm