Tips for Stronger Tomato Seedlings
A deeper dive into Episode 149 of the Garden Basics with Farmer Fred podcast
Late October may seem like an odd time for discussing starting tomato plants from seed (unless, of course, you’re gardening south of the Equator). However, many gardeners here are reliving the 2021 growing season, wondering…what went wrong?
Such was the missive of a caller to the Garden Basics with Farmer Fred podcast in Episode 149. Ken from Palo Alto (CA) asked, “Why did my tomato seedlings turn out so skinny and performed poorly?”
Me, being a guy, answered directly: “probably a lack of light.” Debbie Flower, retired college horticultural professor, being an empathetic gal, who has spent decades coaxing the best out of college students, first congratulated Ken for going the extra step and starting his own tomato plants from seed, stressing the satisfaction that gardeners get from taking something as insignificant-looking as a tiny seed and giving it what it needs to become a productive garden plant. Debbie has that knack, seeing the garden year after year through learning eyes, new gardeners who are amazed and enthralled with the results of their expanding horticultural knowledge. She celebrates along with them.
We pointed out (after I begrudgingly agreed with her…she’s right, as usual) that there are so many more interesting and tasty varieties of tomato seed available than there are plant varieties available at nurseries and garden centers.
Still, Ken…I think it’s the light. And, the first thing Debbie brought up is something I have been practicing for years to get stronger tomato seedlings:
Yep, moving air, as little as 10 minutes a day (or more) from a nearby oscillating fan can lead to stronger tomato seedlings. Add it to your repertoire next spring. Or this month, if your in Aukland (not Oakland).
Strong light, moving air, correct water and fertilization, and the right soil mix for seeds goes a long way to getting your seeds off to a good start. By the way, even though tomato seed starting is something best left until January or February, now is the time to start checking the online seed catalogs for tomato seed varieties that are in stock. Because come late winter…those seeds may no longer be in stock. The last two years, seeds have been disappearing from seed racks as soon as they appear. Expect this shortage to continue. Shop early for best selection.
My favorite online tomato seed sources include Tomato Growers Supply Company; Totally Tomatoes; Baker Creek; Johnny’s; Burpee; and Park Seed. Many of these outlets also feature sales this time of year to drum up business.
Tips for a Great Tomato Garden
If next year is the year for you to grow terrific tomatoes, follow these seed starting tips:
Choose suitable varieties. California's Central Valley weather is most noted for its hot, dry summers. Wherever you live, there are varieties geared for your climate. Check with your local Master Gardener group or Cooperative Extension for suggestions. Here are a few that have done well here in California’s Central Valley, low foothills and East Bay.
Heirloom tomatoes, varieties that were around before the 1950's, are gaining popularity. Although they may not have the built in disease resistance or high production of modern hybrid varieties, they make up for it...with outstanding taste! Among the heirloom varieties you might want to try: Brandywine, Old Brooks, Arkansas Traveler, Dad's Mug, Anna Russian, Aunt Ginny's Purple, Dr. Lyle, Dr. Neal, German, German Johnson, Mortgage Lifter, Pruden's Purple and 1884.
Among my all-time favorite heirloom tomato varieties:
Some of my favorite small tomatoes. Going clockwise, from bottom left: Sungold, Sweet Million, Juliet, Gardener’s Delight
Using home-saved tomato seeds. If you want to save seeds of a particular tomato variety, remember that many varieties are hybrids; they may not necessarily come back with the same traits as the tomato you enjoyed last season (some growers disagree with that statement. Do you feel lucky?). Open pollinated or heirloom tomato seeds are fine for saving, as long as they are grown at least 30 feet away from any other varieties. For best results: save the seeds from tomatoes that are overly ripe; rinse off as much of the flesh and protective gelatinous coating from the seeds as is possible. Then, soak the seeds in a jar of water for a couple of days to remove the rest of the coating. The seeds will sink to the bottom, the gel will float. Discard the gel, remove the seeds and let dry on a paper towel. Then, store in an airtight container in a cool, dry location.
Start seeds in late winter. Mid-January, February and into March are the best months for starting tomato seeds. This will allow 8-12 weeks for the plant to get off to a good start in a warm, sunny place, such as a south or west facing window. It usually takes 7-14 days to germinate tomato seeds. To test for viable seed that you've been saving: moisten a coffee filter, and place a few seeds in the filter, with space between the seeds. Place the filter in an old yogurt container, cover it, and place in an area out of direct heat. Check every few days to see if seeds have sprouted.
Give seeds a healthy start. Use a light, quick-draining potting mix. Commercial seed-starting potting mixes are available; or, mix your own, using 4 parts compost, 2 parts peat moss, and 1 part each of vermiculite and perlite. Any small container with drainage is OK for starting tomato seeds. Fill containers about 3/4 to the top with the potting mix. Water, let drain. Plant seeds shallow, no deeper than 1/4 of an inch. To hasten germination, use a heating pad designed for seeds, such as a propagation mat. This will warm the soil to 70-75 degrees, which tomatoes need to germinate. Keep the soil mix moist. To prevent emerging seedlings from bending too much toward the sunny window, rotate the pots a quarter turn each day. If you are using grow lights, position the seedlings about 6 inches from the light source; keep the lights on 15-18 hours a day.
Movin' on up. When two or three sets of true leaves develop on the tomato seedling, you can transplant it to a bigger pot. This is especially helpful if you started your seeds in a flat or in a small peat pot, or the young stems are bending toward the light at a sharp angle. When transplanting to a bigger pot (preferably a 4-6 inch pot, but no larger than a one gallon container), prepare the new pot the same as before. However, don't fill the pot as full. Place the tomato seedling, with as much of the original soil as possible to avoid disturbing the roots, into a 1/3 to 1/2 filled pot. Then, add moistened soil mix all along the stem, up to the bottom set of leaves. If you are growing tomato seedlings in a flat, thin them out so that there are six inches between plants. This will lessen the chance of root entanglement and damping off, a fungus disease that kills young seedlings. Help your tomatoes develop a strong stem by running an oscillating fan nearby, on low, for about 10-15 minutes a day.
Timing is everything. Acclimate any indoor-grown tomato seedlings slowly to their new outdoor home; this lessens the shock to the plant, allowing it to grow at a quicker pace. About 10 days before setting out into its permanent garden home, place out during the day in a shady or semi-shady location; bring plants in at night.
Mid-Spring is Tomato Planting Time. Plant tomato transplants when the soil has warmed enough to keep the plant actively growing. In most of California, mid-April through early May is the optimum time to set tomato plants outdoors, unprotected, in a garden area that gets full sun. If you can't wait that long, protect those tender young plants with hot caps, row covers or insulating plant protectors - plastic, cone shaped enclosures that are filled with water which collect heat during the day, slowly releasing the heat at night. One criteria for determining when to plant tomatoes outdoors: wait for the overnight low temperatures to be consistently in the 50's.
Plant deeply. Place the tomato deep into the soil, clipping off the lower leaves and leaving only the top leaves and branches exposed. This will cause more roots to develop along the stem, speeding development.
Mulch? Yep! Surrounding your tomato plants with three inches of an organic mulch beneath the plants helps moderate soil temperature, reduces water evaporation, controls weeds and helps to feed the soil as it breaks down. Some gardeners use red plastic mulch beneath their tomato plants. University studies have shown that this can produce an earlier, bigger crop of tomatoes. Other studies indicate that the reduction of light spectrum that results with the use of red plastic mulch may stress the plant into producing most of its fruit earlier in the season, with reduced production in the late season. Your call.
Stake, stake, stake. Supported tomato plants produce more fruit and are subject to fewer problems. One of the best tomato support systems that can be used repeatedly for a number of years include "cages" made from concrete reinforcement wire. A 50-foot roll of this six-inch mesh, five feet-high wire can be cut to make about a half dozen tomato cages, each with a diameter of two to three feet. The six inch mesh allows for easy access at picking time. Stake and tie the cages to the ground, with one stake on either side of the cage. Concrete reinforcement wire is also sold in convenient, 4’x5’ sheets. Bend it in a circle, secure the circle with zip ties.
