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Get the scoop on growing tomatoes from seed | TribLIVE.com
Jessica Walliser, Columnist

Get the scoop on growing tomatoes from seed

Jessica Walliser
| Sunday, January 13, 2019 12:00 a.m
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Jessica Walliser
Juicy tomatoes are easy and inexpensive to grow from seed.

Everyone loves growing tomatoes, but not everyone takes the time to start their own plants from seed. Most gardeners head to their favorite local nursery and pick up a few transplants when planting time arrives. But, starting your tomatoes from seed means you’ll have a far wider selection of varieties and you can save yourself a few dollars. The cost of a single tomato transplant in a 3-inch-pot is the same as the cost of a packet of a few dozen seeds. If you’ve never grown your own tomato plants from seed because you’re afraid of doing it wrong, don’t fret. Growing tomatoes from seed is a fairly easy endeavor and requires just a few inexpensive items.

Growing tomato plants from seed starts with making sure you have the right equipment on hand. First, you’ll need a packet of seeds. I split seed packets with a friend. We each pay half of the cost and then take half of the seeds. It’s a great way to save money while still getting to grow a variety of tomatoes.

Next, you’ll need a clean container in which to start your tomato seeds. You can purchase a seeding flat from a nursery or online source, or just use any washed and rinsed container that has a few drainage holes cut in the bottom. Good candidates include yogurt cups and plastic take-out clamshell-type containers.

You’ll also need a bag of high-quality, seed-starting potting soil. Don’t skimp on this item because when it comes to potting soil, you get what you pay for. Good seed-starting mixes are made from a base of peat moss or coir fiber, often mixed with perlite or vermiculite, and a source of nutrition for your plants. Choose a potting soil formulated specifically for seed starting as it will be lightweight and have the best balance of nutrients for young seedlings.

Fill the container with potting soil, leaving at least ¼ inch of head space at the top to collect and channel irrigation water. Sow your tomato seeds about ¼-inch deep, barely covering them with a light layer of potting soil. Label each variety. This process should be done about 6 to 8 weeks before our last expected spring frost. Here in Western Pennsylvania, the best time to start tomato seeds is mid to late March. Starting too early could result in lanky, overgrown seedlings that are difficult to transplant.

Water in the seeds and cover the container with a piece of plastic wrap or a clear dry cleaning bag. The plastic keeps the humidity high until the seeds can germinate. Ideally, you should place the seeded container on a heat source, to raise the soil temperature to 70-75 degrees F. This hastens and improves germination. Electric seedling heat mats are available from garden centers for this job, or you can put the flat on a forced air register, radiator, or even on top of the fridge. As soon as the seeds germinate, remove the plastic covering, take them off of the heat source and move them under grow lights or to a bright windowsill.

While growing tomatoes from seed on a sunny windowsill is possible, it’s likely that the seedlings will be elongated and pale. Even the brightest window does not throw as much light as an artificial lighting system does. Still, if you only have a window, rotating the container a quarter turn every day helps to even out their growth.

You don’t need a fancy grow light system to start seedlings; a simple fluorescent shop light fixture will do. The trick is to install it on chains so it can be raised as the seedlings grow. Keep the lights 2-3 inches from the plant tops and leave them on for 18-20 hours per day.

Be sure to provide your tomato seedlings with water as necessary, and begin to fertilize them with a half-strength liquid, organic fertilizer every three weeks once they develop their second set of leaves. This is also the point at which you should transplant your seedlings.

Separate your tomato seedlings and pot them up into a slightly larger container filled with regular potting soil soon after they grow their second set of leaves. Plant them deeply, right up to the base of their lowermost leaves. This helps them form a good root system.

Continue to care for your tomato plants until the danger of frost has passed, typically around mid-May here in Pennsylvania. Then, slowly acclimate your seedlings to outdoor conditions by moving them outdoors, into a shady area, for a few hours every day and then taking them back indoors before nightfall. Gradually increase the amount of time they spend out doors as well as the amount of sunlight they’re exposed to until they’re outdoors full time. This process should take about 2 to 3 weeks.

After the seedlings are fully acclimated to outdoor conditions and frost no longer threatens, plant your tomato babies out into the garden and prepare to enjoy your first luscious bite of homegrown tomatoes in a few short months.


Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden,” “Good Bug, Bad Bug,” and her newest title, “Container Gardening Complete.” Her website is jessicawalliser.com. Send your gardening or landscaping questions to tribliving@tribweb.com or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.


Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden,” “Good Bug, Bad Bug,” and her newest title, “Container Gardening Complete.” Her website is jessicawalliser.com. Send your gardening or landscaping questions to tribliving@tribweb.com or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.

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