Start Seeds Indoors for a Texas Spring Garden

Texas springs are short. The window between the last frost and the first 95°F day can be eight weeks. Transplants beat that window; seeds sown directly in the garden often do not. Starting seeds indoors gives your plants a six-week head start.

It also gives you variety. A garden center sells a dozen tomato varieties as transplants. A seed rack sells a hundred.

Work backward from your last frost date

Find your average last frost date first. Use our hardiness zone finder if you do not know it. Then count backward:

• Tomatoes: start seeds 6 weeks before the last frost.
• Peppers and eggplant: start 8 weeks before. They germinate and grow slowly.
• Broccoli, cabbage, and cauliflower: start 10 to 12 weeks before. They go outside a month before the last frost.
• Squash, cucumbers, and melons: start only 3 weeks before, or sow them directly. They dislike transplanting.
• Example for zone 8b (Austin, last frost around March 1): start peppers on January 5 and tomatoes on January 18.

Use clean containers and seed-starting mix

Any container with drainage holes works: cell trays, yogurt cups, or egg cartons. Wash used containers with soapy water first. Disease from last year's soil kills this year's seedlings.

Fill the containers with seed-starting mix, not garden soil. Garden soil is too dense and carries fungus. Moisten the mix before you sow. Plant each seed at the depth listed on the packet, which is usually twice the seed's width.

Give seedlings strong light and steady moisture

A windowsill is not enough light in January. Seedlings on a windowsill grow tall, thin, and weak. Use a shop light or an LED grow light. Hang the light two to three inches above the leaves. Raise it as the plants grow. Run it for 14 to 16 hours per day on a timer.

Keep the mix moist but never soggy. Water from the bottom: set the tray in an inch of water for 20 minutes, then drain it. Aim a small fan at the seedlings on low. Moving air prevents fungus and builds stocky stems.

Harden off before you transplant

Indoor seedlings have never felt sun or wind. Direct planting kills them. Harden them off over 7 to 10 days:

• Days 1 to 3: set the plants outside in shade for 2 to 3 hours.
• Days 4 to 6: give them morning sun, then bring them in.
• Days 7 to 9: extend to a full day outside.
• Day 10: transplant in the evening, and water them in well.
• Skip a day if the wind is strong or a cold night is forecast.

Buy the hard ones, start the easy ones

Some plants are not worth starting at home. Onions, strawberries, and most herbs cost little as transplants and take months from seed. Start tomatoes, peppers, and anything unusual. Buy the rest from your local garden center, where the varieties already suit your area.