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Growing Excellent Tomatoes

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This article comes from the NOFA/Massachusetts 2013 December Issue Newsletter

Presented by Amy LeBlanc, Whitehill Farm Reviewed by Shawn Ilinitch

Growing excellent tomatoes requires understanding your plants’ unique needs throughout each stage of its life, according to veteran farmer Amy LeBlanc, owner and operator of Whitehill Farm in East Wilton, Maine. During the summer, she and her husband grow tomatoes, peppers, eggplants and culinary herbs. They also participate in farmers’ markets and sell products online.

 The first step in growing excellent tomatoes is determining your desired planting date. LeBlanc suggests starting seedlings 6-8 weeks before the last anticipated frost, with adjustments made if you plan to use a greenhouse or hoop house. LeBlanc estimates her last frost date around Memorial Day, so she aims to start her seedlings around April 1.

 LeBlanc chooses a lighter potting soil that is compost-based. She finds that soils that are rich in peat do not allow her plants to breathe and develop properly. She spaces her seeds in 6 by 9 inch trays with approximately ½ inch spacing (3 rows of 12 seeds per tray). When potting, she tries to mound the soil slightly, which keeps the soil level near the outer edge of the tray and prevents a pool and moist air at the soil surface. The mound will settle with watering.

 At this stage in their lives, tomatoes need two things – warmth and moisture. Since light is not necessary, LeBlanc keeps her seed trays on top of heat mats in her bathroom. Optimal germination temperature is between 70-80 degrees, and moisture must be maintained in the soil mixture. Usually it takes 6-14 days for germination.

 The needs of tomatoes begin to change after germination. At this point in their lives, tomatoes need light and less heat (although they must be kept above 55 degrees). A windowsill may not provide enough light. The seedlings also must be checked regularly to see if they are leaning toward the light. If so, they must be adjusted. LeBlanc has found the most success using fluorescent lights positioned about 3 inches above the seedlings. She uses two different bulbs to provide full spectrum lighting. Each lamp has two different bulbs – a 6500K blue spectrum and 4800K red spectrum.

 Once the seedlings have developed their second true set of leaves, they are ready to be transplanted into individual containers. According to Leblanc, it is the height of the seedling that is most important. Because of the close spacing she began with when seeding, by now her plants have grown tall, allowing for deep burial. The seedlings should be buried to their first set of true leaves, allowing roots to form along the remainder of the stem.

 In 7-8 weeks, the seedlings are nearly ready for the garden. Plants should be hardened off before they go to the field. They should be left outside in a shady area protected from wind. Each day their exposure to sun should be increased, and they should be ready in a few days.

 When transplanting, plants should be placed as deep as possible in a well-drained soil that is rich in organic matter. LeBlanc removes the bottommost leaves of her plants and buries them up to the remaining first true leaves. While she doesn’t use trenching (burying the plant sideways at an angle to develop more roots) she says it can be effective if you want to grow taller plants. LeBlanc mulches immediately after planting and then waters her plants. She uses a mild fish emulsion for a week or side dresses with compost or an organic granular fertilizer. When blossoming begins, LeBlanc does a foliar feed (applying fertilizer directly onto the leaves) using a very mild fish emulsion.

 Tomato growers have options for supporting their plants, including stakes, cages, and trellising, according to LeBlanc. If using traditional cages, you need to drive a tall stake into the northwest side to prevent it from tipping over later in the season. LeBlanc says she makes large, heavy duty towers made of concrete reinforcing wire. These cages, buried deeply, do not need the additional stake and can be used forever.

 Once transplants have firmly established themselves, their needs change once again.

To understand the growth of tomatoes, one must know the two stages of vegetable growth. During the vegetative stage, when a plant uses the products of photosynthesis to grow more stems and leaves, growth is the priority. The priority shifts to fruit and seed production during the generative growth stage. Tomatoes can undergo both stages simultaneously.

 LeBlanc says she continuously monitors the top 8-10 inches of the plant; this represents the most recent growth. Signs of vegetative growth include thick stems, light yellow flowers, heavier foliage, and small fruits that are slow to ripen. Generative growth characteristics include thinner stems (especially at the top 7-10 inches of growth), darker yellow flowers, sparser and lighter green leaves and larger fruits that ripen promptly.

 When tomatoes have reached their mature stage, growers can encourage ripening by reducing vegetative growth. At this point, no fertilizer should be applied. Growers should water much less frequently, but they should water deeply when they do. Cooler nights that occur later in the season also encourage the generative stage. According to LeBlanc, when you stress plants they feel the need to finish their life cycle by producing their fruits and seeds.

 Finally, even the most veteran tomato growers may face diseases and pests. LeBlanc says it is important to recognize the difference between diseases and cultural and environmental factors such as overwatering, drought stress, or temperature. For example, blossom end rot is a secondary infection that indicates a calcium deficiency that can be caused by uneven watering.

 LeBlanc suggests the following websites to diagnose nutrient deficiencies and diseases in tomato plants:

Daily scouting is necessary to reduce pest problems. LeBlanc says she has found success checking her plants every night with a handheld black light to help locate tomato hornworms. The worms can be easily distinguished from the plants using this method and easily picked and destroyed.



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