By Stephen Brueggerhoff, CEA – Horticulture, Brazos County AgriLife Extension; published 12/30/2024

While winter is a time of renewal, a natural cycle that whispers for stillness and contemplation, I find that I am not one to rest on my laurels. We are already planning ordering new tomato varieties to be used as trial plants this spring and scheduling for winter seed propagation. There are advantages to starting tomato varieties and other vegetables by seed, such as earlier harvest and the potential to lessen insect infestation, producing ahead of pest life cycle such as Leaf-footed Bugs for tomatoes and Squash Vine Borer for zucchini and summer squash. The following are some tips to keep in mind when starting your tomato veggie garden.

Choose varieties based on proven performance. Refer to your own success and ask friends or relatives for winning varieties that are reliable performers for the region. You can also rely on research results from our Extension efforts. I am assigning a tomato research demonstration project to the 2025 Texas Master Gardener Training class this coming spring. Brazos County Master Gardener Fred Rapczyk has chosen twelve tomato varietals that the class will grow out and collect harvest data, culminating in a report we will provide to the public of proven varieties that will perform best in the Brazos Valley for home growing efforts. Fred has graciously offered to germinate the tomatoes and have ready for the class to transplant into the research beds. On trial are medium-sized Celebrity, green variegated Green Zebra, Red Snapper, Heirloom Marriage and yellow-skinned Taxi; paste tomatoes San Marzano, La Roma III and Plum Regal; and cherry tomatoes Juliet, Yellow Pear, Sun Sugar and Supersweet 100. While one can always choose from the random assortment of seed packets available from local retail outlets, you can also order online for unusual or specialty varieties that you would like to try out. Consult with your local feed store or garden center for bulk seed and local supplies.

Timing is everything

Germinate tomato seed indoors and by mid-January to have them ready for transplanting by early to mid-March. I can tell you from experience not to start seeding too early. In mid-December 2018, I experimented with earlier germination of tomato varieties and had to take extra steps to slow down growth as the plants were a little too leggy when transplanted the following spring. Always pay attention to the days of harvest or maturity listed for each variety, a specific guide to estimate seasonal planting time and harvest.

Consistency is key to success

For media, use a soil-less mix developed for seed germination. While you can germinate the seedlings in a variety of sterilized containers, I prefer using seed trays, which are pre-formed black plastic trays that have from 16 to 32 connected individual cells measuring approximately 1.3 cubic inches per cell. The advantage to using this kind of tray is control of the number of plants in cultivation. There is also adequate space for soil volume to accommodate newly emerging roots. Bonus, you also have an individual plant growing in a cell that can easily be removed without causing damage to the roots. A minor disadvantage is you may have to pot up an individual plant to a 3-inch container about half-way through growing to finish and prior to transplanting. Whatever container you use, place them in a larger tray to bottom water the plants and keep the media evenly moist from germination through root establishment.

The optimum germination range of soil temps for tomatoes is between 70 to 85-degrees. To maintain soil temperature consistency, use a soil warming mat and place below the catchment tray. These are waterproof heating pads that have been developed specifically for the task, are reasonably priced and provide consistent heat to keep soil at the recommended germination temperature. To simulate a natural cycle and for optimal growth, ambient air temperature can fluctuate by about 10-degrees between 70-degrees day and 60-degrees at night. Under these conditions, you will witness seedling emergence within five to eight days.

Once the seedlings emerge, you will need to provide adequate direct or simulated sunlight to maintain growth. Light exposure through a southwestern facing window will not suffice during this critical growth stage and will require supplemental lighting to keep the plants from becoming too leggy. Plant growth is initiated through exposure to violet-blue and orange-red wavelengths. While you can use fluorescent shop lights you may have on hand, they emit light toward the blue end of the spectrum, and it is best to invest in full spectrum grow lights. Improvement in product development provides an option for the use of full or balanced spectrum LED lights. LED lights may be a little more expensive on the front end, but the advantages are reduced weight, and some are manufactured so that you can adjust the light spectrum. Suspend the light from a chain on a stand so that you can adjust the distance between the light and plants as they grow. Two to 4-inches above the growing surface or emerging vegetation and from 14 to 16 hours per day.

Never a dull moment for gardeners! Keep on planning for growing and planting. Happy holidays to you and your family, and I look forward to seeing you in the garden in the New Year.