How to Grow Tomatoes

The biggest tomato mistakes US gardeners make

Most home tomato failures in the US come down to four problems: planting too early into cold soil, inconsistent watering, too much nitrogen fertilizer, and failure to manage foliar disease before it spreads.

Tomatoes are the most popular home garden vegetable in the US, grown by approximately 35% of households with any garden space. They are also the most failure-prone. The problems that kill tomato production are well understood — and almost entirely preventable.

This guide focuses on the decisions that matter most for US gardeners: variety selection for your zone, timing, soil prep, watering, and the disease and pest problems most likely to cut your harvest short.

Determinate vs. indeterminate: which type to grow

This is the first decision, and it affects everything from staking requirements to harvest timing.

Determinate varieties produce all their fruit within a 2–3 week window and then stop growing. This is an advantage in Zones 3–5 where the season is short — all the fruit ripens before frost. It’s also ideal for gardeners who want to can tomatoes, since all the fruit arrives at once.

Indeterminate varieties vine continuously and produce fruit all season long from midsummer to first frost. They require more staking, more pruning, and more space, but provide a consistent fresh harvest. Most heirloom varieties are indeterminate.

When and how to plant tomatoes

Plant tomatoes when soil temperature reaches 60°F — not by calendar date alone. A thermometer check 4 inches deep is more reliable than any last-frost date chart. Cold soil — even in air temperatures above 60°F — stops root development and stuns plants for weeks.

Most US zones:

• Zones 3–4: Late May to early June
• Zones 5–6: Early to mid-May
• Zones 7–8: April to early May
• Zones 9–10: February to March; fall planting also works

Check your specific last frost date and zone at the planting zones guide.

Hardening off: Tomato transplants started indoors need 7–10 days of outdoor exposure before planting. Move them outside in shade for 1–2 hours the first day, increasing sun exposure daily. Skipping this step produces transplants that sunburn and stall after planting.

Planting depth: Bury two-thirds of the stem — far deeper than it was in the pot. Tomatoes form roots along any buried stem, creating a much larger and more drought-resistant root system. Remove all leaves from the portion being buried.

Spacing: 24–36 inches between plants for caged or staked indeterminate varieties. 18–24 inches for determinate bush types. Too-close spacing creates humidity and poor airflow, which fuels fungal diseases.

Soil preparation and fertilizing

Start with good soil: Mix 3–4 inches of compost into the top 10–12 inches before planting. Tomatoes are heavy feeders and need well-drained, organically rich soil. See how to start composting for making high-quality compost for your vegetable beds.

Fertilizer timing:

• At planting: Balanced fertilizer (10-10-10) at the recommended rate worked into the planting hole
• When first flowers appear: Switch to a low-nitrogen, higher-phosphorus formulation (like 5-10-5 or tomato-specific fertilizer). Too much nitrogen after this point produces lush foliage and few tomatoes.
• Monthly through the season: Continue low-nitrogen applications until 4 weeks before first frost

What not to do: Applying high-nitrogen fertilizer (lawn fertilizer, chicken manure) after the plant has flowered produces plants that grow vigorously but set little fruit. The foliage looks spectacular; the tomato yield is poor.

For a complete vegetable garden setup including bed preparation for tomatoes, see how to start a vegetable garden.

Staking and support

Every indeterminate tomato needs support installed at or before planting. Installing a cage or stake after the plant is established damages roots.

Cage: Works for most home gardens. Use heavy-gauge wire cages at least 18 inches wide and 5 feet tall. Smaller, thin-wire cages from discount stores are not adequate for a full-size indeterminate plant. A ‘Brandywine’ in July will crush a lightweight cage.

Florida weave: Efficient for a row of tomatoes. Drive stakes every other plant and weave twine in a figure-8 pattern between plants and stakes. Add a new level of twine every 8–10 inches of growth.

Single stake: Drive a 6-foot stake 12 inches into the ground at planting. Tie the main stem to the stake every 8–10 inches with soft ties as the plant grows. This method requires the most consistent maintenance.

How to prune tomatoes

Prune indeterminate tomatoes by removing suckers — the shoots that emerge from the junction between the main stem and a branch (the leaf axil). Removing suckers improves airflow, reduces disease pressure, and focuses energy on existing fruit. See the complete how to prune tomatoes guide for step-by-step instructions with timing.

Do not prune determinate varieties. Removing suckers from determinate plants removes potential fruiting sites and reduces total yield.

Watering tomatoes correctly

Water deeply 2–3 times per week rather than lightly every day. This is the single most impactful change most tomato growers can make. Shallow daily watering keeps roots near the soil surface. Deep watering drives roots 12–18 inches down, producing plants that tolerate heat stress and produce consistently.

Blossom end rot is the most common tomato problem in the US and is directly caused by inconsistent watering. The dark, sunken rot at the bottom of the fruit is calcium uptake failure — calcium in the soil is not being carried up to developing fruit because soil moisture is fluctuating too much. The fix is consistent deep watering, not adding calcium to the soil (though soil calcium should be adequate — test if you’ve had repeated problems).

How much to water: 1–2 inches per week in moderate weather; up to 3 inches per week in temperatures above 90°F. Use a soaker hose or drip irrigation at the base — wet foliage invites fungal disease.

Mulch: Apply 3 inches of straw or wood chip mulch around plants to retain soil moisture, regulate temperature, and reduce splash of soil-borne diseases onto lower leaves.

Common problems and solutions

Early blight (Alternaria): Brown spots with yellow halos on lower leaves, moving up the plant. Most common in humid eastern US climates in warm, wet summers. Prevention: stake plants for airflow, mulch to prevent soil splash, remove lower leaves that touch the soil, and water at the base only. Once established, treat with copper-based fungicide.

Septoria leaf spot: Small circular spots with dark borders. Same conditions and same prevention as early blight. Very common in the Mid-Atlantic and Southeast.

Tomato hornworm: Large green caterpillar up to 4 inches long. Strips foliage rapidly. Handpick when spotted. See Japanese beetle control for additional information on garden pest management approaches that apply to tomato pests.

Cracking: Radial or concentric cracks in ripe fruit. Caused by irregular watering — a dry period followed by heavy rain or irrigation. Consistent soil moisture is the fix.

Blossom drop: Flowers open but fall off without setting fruit. Most common when temperatures exceed 95°F during the day or drop below 55°F at night. Neither extreme is something you can prevent — shade cloth or row cover helps at the margins.

Companion plants for tomatoes

Several plants improve tomato production when grown nearby.

Marigolds (French type) suppress root-knot nematodes in the soil and deter aphids. Plant them 12 inches from tomato stems around the bed perimeter.

Basil is the most traditional tomato companion. Some evidence suggests it improves flavor; strong evidence shows it deters thrips.

Borage attracts pollinators and repels tomato hornworm. Grows large — plant 18–24 inches from tomato stems.

For a complete companion planting plan for tomatoes, see tomato companion plants for the full list of beneficial, neutral, and harmful companions.

Harvest timing

Tomatoes ripen best on the vine but can be finished indoors. When temperatures above 85°F persist, tomatoes stop producing the enzyme needed for red pigmentation. Fruit remains orange and off-flavored even when technically ripe. In heat waves, pick tomatoes when they show first blush of color and ripen indoors at 65–70°F.

Do not refrigerate tomatoes. Cold storage destroys the volatile compounds responsible for flavor. Store at room temperature and eat within 3–5 days of full ripeness.

For US zone-specific planting calendars and variety recommendations by state, Cooperative Extension Offices at land-grant universities provide free, research-based tomato guides tailored to each state’s climate and pest pressure.