Seed Starting: Grow Your Own Transplants

Why it matters

Starting your own transplants lets you grow the exact high-yield, Texas-tough varieties you want, in the numbers you need, for a fraction of nursery prices. Getting them into the ground on time, before the heat arrives, is how you get a big Texas harvest.

Step by step

1. Count back from your frost date Tomatoes need 5-6 weeks from seed to transplant size, peppers and eggplant 7-8, broccoli and cabbage 5-7, lettuce 4-6, onions 8-10, and squash, cucumbers and melons only 2-3.
2. Use clean containers and sterile mix Use cells or pots with drainage holes and a commercial seed-starting or soilless mix. Never use backyard or garden soil, which is heavy and full of weed seeds.
3. Sow at the right depth Cover seeds to about twice their diameter: 1/4-1/2 inch for tomatoes, peppers, lettuce and cabbage, and 3/4-1 inch for squash and melons. Sow 2-3 seeds per cell and thin to the strongest one.
4. Keep them warm to sprout Tomatoes, peppers, eggplant, cabbage-family crops and squash sprout best in soil around 85°F. Lettuce and onions prefer about 75°F. A seedling heat mat helps.
5. Give strong light right away As soon as seedlings pop up, give them 12-14 hours of light a day. Hang lights about 2-3 inches above the tops and raise them as plants grow.
6. Grow them cooler After they sprout, most vegetables like nights of 60-65°F with days about 10 degrees warmer. Cool-season crops like nights near 55°F.
7. Water and feed lightly Water when the mix no longer feels moist, or set trays in 1-2 inches of water to soak from below. Feed weekly with water-soluble fertilizer at half strength.
8. Harden them off Starting 1-2 weeks before planting out, set seedlings outside in shade for a couple of hours, then give them more time and more sun each day until they stay out all day.
9. Transplant on a calm, cloudy morning Keep the root ball moist, set plants at the same soil level they grew at, water them well, and shade them from harsh sun for 2-3 days.

Key facts

• Weeks from seed to transplant: tomato 5-6, pepper and eggplant 7-8, broccoli/cabbage/cauliflower 5-7, lettuce 4-6, onion 8-10, squash/cucumber/melon 2-3 (AgriLife).
• Best germination soil temperature: about 85°F for tomato, pepper, eggplant, cabbage family and cucurbits, and about 75°F for lettuce and onion (AgriLife).
• Light: 12-14 hours a day, with lights 2-3 inches above the plants (Utah State).
• Seedling temperatures: tomatoes 70-80°F days and 60-65°F nights. Cabbage family 60-70°F days and 50-60°F nights (AgriLife).
• Seed depth: about 2 times the seed's diameter.
• Feed seedlings weekly at half-strength liquid fertilizer if the label gives no seedling rate (Utah State).
• Hardening off: 1-2 weeks. Keep tender seedlings above 45°F. Leave cucumbers and melons out overnight only above 50°F (Univ. of Maryland).
• After transplanting, water daily for the first week and hold off on fertilizer for 10-14 days (UF/IFAS).

Texas notes

• Average last-frost dates (50% chance) from AgriLife: Houston Feb 12, Austin Mar 16, Amarillo Apr 15. Count back from yours.
• Example: for Austin tomatoes, 5-6 weeks before Mar 16 means sowing indoors in early February.
• Texas springs heat up fast, and tomatoes stop setting fruit in high heat. Starting on time is what gets you a big spring crop.
• For fall gardens, start tomato and pepper seed in early summer. AgriLife lists Jul 25 as the last good tomato transplant date in Region III (Central Texas) and Sep 1 in Region V (Rio Grande Valley).
• Start fall broccoli, cabbage and cauliflower in mid- to late summer. AgriLife lists Sep 20 as the last good transplant date in Region III.
• Fall transplants set out in late-summer heat need daily water for about 2 weeks and afternoon shade while they settle in.