key growing information

How to Grow Tomatoes From Seed

How to grow tomatoes: determinate vs. indeterminate types, soil and feeding, starting and potting up transplants, planting out, staking, pruning, pests, harvest and storage.

By Hensley’s Seed Co. September 3, 2026

Tomatoes - Key Growing Information

A stand of indeterminate tomatoes being grown using a stake-&-wire trellis / hanging-string system.

SCIENTIFIC NAME:

Solanum lycopersicum

DAYS TO MATURITY:

From transplants.

DETERMINATE (BUSH):

These varieties need no pruning and can be grown with or without support; the fruit ripens over a concentrated period.

INDETERMINATE (CLIMBING):

These varieties do best staked, trellised or caged, and pruned; the fruit ripens over a long period.

CULTURE:

Tomatoes prefer moderately rich soil with a pH of 6.0–6.8. Feed carefully, since too much nitrogen causes rank growth, rot and late ripening. For short determinate types, plant in succession every 4–6 weeks. Seed usually germinates in 5–7 days.

TRANSPLANTING:

Don't start seed too early: leggy, rootbound or flowering transplants can stall and yield less early fruit. About 5–6 weeks before transplanting, sow ¼" deep in 20-row flats at 20 seeds per row, or one seed per cell in 200-cell trays, and cover lightly. Hold the mix at 75–85°F (24–29°C) with moderate moisture. At the first true leaf, pot up into 50-cell trays or 4" pots, depending on when you expect to plant out. Grow at a steady 60–70°F (16–21°C) and feed with a complete fertilizer until hardening off; extra light and cooler nights keep plants from stretching. For the earliest crop, plant under row cover around the last frost date, and don't leave unprotected plants out through several nights below 45°F (7°C). In rows 4–6' apart, space determinates 12–24" and indeterminates 24–36". Plant deep to encourage roots along the stem, and water in with a high-phosphate fertilizer solution to help early yields.TRELLISING: For the basket weave, drive 5–6' stakes every 2–3 plants, with sturdier T-posts at intervals and at the row ends. For tall indeterminates, add short extensions or prune once plants grow beyond an easy picking height.PRUNING: Indeterminates usually benefit from removing every sucker below the first strong branch just under the first flower cluster. Those low suckers often miss the trellis, set fruit near the soil, draw energy from the top of the plant, and help soil-borne disease spread. Late in the season, thinning leaves can improve airflow, and topping plants helps the last fruit ripen.

INSECT PESTS AND DISEASE:

Get to know your common pests and the ways to control them, including resistant varieties and pesticides. Don't handle plants when they're wet or after using tobacco, and keep leaves dry where possible. Manage crop debris and rotate crops.

HARVEST:

Fruit ripens gradually from the blossom end up to the shoulders, and from the base of each cluster out to the tip. Pick soft fruit into shallow, padded trays without stacking. Save fully ripe fruit for local sales or home use; the farther and longer it has to travel, the less ripe it should be when picked. Any fruit that has begun to color will finish ripening after picking. You can remove the calyx or leave it on as a sign of freshness.

STORAGE:

Unblemished, nearly ripe fruit keeps 4–7 days at room temperature in the dark. For longer storage, choose suitable varieties, pick a little less ripe, and hold at 45–60°F (7–16°C); going colder or picking too green costs eating quality.

TRANSPLANTS:

On average, about 850 plants per 1,000 seeds, or 10,200 per oz.

SEEDS/OZ. (AVG.):

11,000–13,000.

PACKET:

40 seeds per packet unless noted, enough for about 60' of plants.