Gardeners Exchange Group Meeting 16 April 2016
Location: Walnut Hill, Home of David and Missy Hill
Topic: Seeds to Seedlings, by David Hill
Submitted by Julie Neely, GEG Secretary
David Hill owns and operates Hill’s Farm Fresh Produce LLC. You may purchase his produce at the Fresh Fruit and Veggie Wagon located at the corner of Old Country Club Road and Highway 340. Our tour focused on the use of the greenhouse, high tunnels, and techniques designed to propagate seedlings, minimize disease, and enhance overall production and quality. New this year are the grafted vegetable plants—tomatoes and a bell pepper. Dave’s flowers, herbs, hanging baskets and grafted tomatoes were available to purchase at the end of the presentation. This GEG presentation is similar to his tour given last year in August, so some of this may sound familiar.
Dave grows and sells flowering plants, herbs, hanging baskets, cucumbers, tomatoes, peppers, kale, broccoli and lettuce on the farm, but the tomatoes are grown exclusively in the high tunnels. Over 5 tons of tomatoes are produced annually, and owing to his techniques, he experiences less than 5% fruit loss. This year’s tour focused on seed starting, flowering plant and tomato plant growing.
The Green House
His veggies and flowers start life as seeds or plant plugs which were all ordered by mid-January. Seeds are planted into sterile potting medium in the climate-controlled greenhouse. The flowers that are harder to germinate from seeds are purchased in large quantities as small plant plugs. Seeds germinate under cover at 78 degrees in 10–14 days and are then transferred to the 75 degree light chamber until they grow their 2nd leaves (true leaves not the cotyledons). Dave achieves 98-100% germination rates using these techniques and he grows over 1500 seedlings annually. He staggers the starting date for the seedlings; this way he can replant in successive waves instead of all at once. When the plants have their second leaves they are transplanted (individually by hand) from the starter plastic trays into 2-inch pots. Dave suggested repotting the tomatoes (except the grafted type) deep, up to the top leaves; this causes the plants to develop healthy root systems and form sturdier seedlings which are not top heavy. He uses this deep planting technique for peppers, kale and broccoli. After 5-6 weeks the plants go from the green house into the high tunnels to harden off for a couple of days before being taken out of their 2-inch pots and replanted into the ground.
The High Tunnels
Dave’s high tunnels are 14 feet tall, 25 feet wide and 75 feet long; they are fully screened—no bugs get in or out. The tomatoes are grown in compost rows which are covered by black plastic. (Compost is purchased from the Tabb’s). This is a change in growing technique since last year. Dave explains that the plastic grow bags he tried last year were not economically feasible because they cost more money to use, require more water and produced lower yields. All good gardeners learn from successes and failures; it’s a constantly evolving science. Dave is extremely careful controlling access to and contact with his tomato plants to avoid contamination with diseases like fungal spores. He explained that, “Soil east of the Mississippi is contaminated with early and late tomato blight.”
Blight is a fungal disease spread by wind-borne spores which germinate on wet leaves, especially tomato, pepper and eggplant. Anything that prevents the leaves from being wet will help prevent blight because once infected the plants will eventually die. So, watering early in the day, planting in full sun (at least 14 hours a day), keeping plants pruned and thinned to allow good air circulation, rotating crops, keeping plants off the ground to avoid soil splash up, and good winter cleanup of dead leaves and plants all help reduce blight. Or, you can use fungicide—but one of the best methods to avoid blight is the use of a green house or high tunnel.
The high tunnel prevents the leaves from getting wet. Dave’s irrigation system consists of tubing running under the black plastic. This system provides water and fertilizer solution to only the roots growing in the “compost mixture” – not onto the leaves. The compost mixture consists of humus, composted manure, compost, perlite, Epson salts and lime (to keep the soil on the acid side, a little below pH7). He trains the vines to grow up cords (using plastic clips) hung from the ceiling of the high tunnel; this prevents the plants from ever touching contaminated soil. Tomato plants are pruned and over-abundant blooms are pinched off; this might seem to limit overall yield but it keeps plants healthy by allowing ventilation between plants and produces large, uniformly perfect fruit ready for the farm market. The tomatoes in the high tunnels demand 4-6 hours of labor per day to keep them fertilized, weeded, pruned and clipped to the cords on which they grow and of course harvested. High tunnels combined with row covers in the winter extend the growing season dramatically; Dave grows vegetables inside his passive solar high tunnels even when the outside temperature is 25 degrees.
So what are the disadvantages to using high tunnels? They cost money; prices vary but Dave’s basic model cost $7500. They get very hot in the summer; adding shade cloth over the exterior helps. They need an irrigation system or you will spend all your time hand-watering. They benefit from a heating system, depending on what you are trying to grow in the winter. They need to have pollinators introduced into them because Dave’s are totally enclosed—no bugs get in or out. Dave uses leaf cutter and mason bees. These non-honey producing/non-colony forming bees are easy to grow in little paper/cardboard tubes which they will fill with eggs the first year. You just harvest the tubes and replace them into your high tunnel in the next growing season. The bees are happy to pollinate for you but you can also spread pollen yourself by shaking plants and cords, a messy and sneezy task. There are newer hybrid tomato varieties that are self-pollinating. Dave is currently putting up two new high tunnels and hopes to have 20,000 square feet “under plastic” soon.
This year Dave purchased grafted tomatoes. He did this because sometimes tasty, desirable tomatoes like heirlooms are not disease-resistant and are difficult to grow. To get around these problems the “top part of the plant,” for example a special heirloom, which grows the flowers and tomatoes, is grafted (joined) to a “new bottom”—a vigorous, highly productive, disease-resistant root stock. (This year Dave used “Maxi-forte” root stock from Johnny’s Select Seeds.) The hybrid plants have the disease-resistant traits of the roots and produce the special tomato flavor that you like to eat. The only trick to these plants is to be careful NOT to plant them too deep. The top part above the graft can never touch the soil because it may start to develop its own roots. It would then revert back to the “top part only” non-disease-resistant plant. These grafted plants have to be handled carefully at first and are grown in special dark, warm (84 degrees), humid (85%) healing chamber for three days. The grafted tomatoes produce 2-3 times more fruit and produce fruit earlier than tomatoes grown from seeds. The grafted plants require more fertilizer to support these higher yields. Dave uses “Dosatron injectors” to mix his fertilizer solutions into the irrigation water. These injectors are costly but well worth the initial investment.