How to Grow Tomatoes in the USA

Quick Facts

At a Glance

Diseases

Grey mould

common

Botrytis cinerea

Soft brown fruit decay; Fuzzy grey-brown mould

RHS: tomato "may be susceptible to... grey moulds under glass" (Red Cherry cultivar page); RHS grey mould disease page independently lists tomatoes among commonly affected crops.

Verticillium wilt

high

Verticillium dahliae

Verticillium wilt now links tomato and strawberry -- second disease (after Damping-off/Grey mould) proven reusable across both flagship crops.

Cucumber mosaic virus

Cucumber mosaic virus (CMV)

UC IPM names tomato among CMV hosts: "cucurbits (except watermelon), tomato, spinach, celery, safflower, beans, blackeyes, peppers, beets, potatoes, many ornamentals and weeds". The RHS page did not list tomato.

Late blight (potato blight / tomato blight)

severe

Phytophthora infestans

Rapidly spreading watery rot with pale leaf-edge sporulation (late blight pattern)

Retroactively linking tomato (already in graph) to the same Late blight disease entity now that potato -- the other major host -- has been added. RHS/UMN both confirm Phytophthora infestans is the identical pathogen…

Powdery scab

minor

Spongospora subterranea

Raised or sunken scabby patches on tuber/root skin

RHS: powdery scab "sometimes infects the roots of tomato plants" -- second cross-crop (potato/tomato) disease link established this session, alongside Late blight.

Tomato spotted wilt

moderate

Tomato spotted wilt virus (TSWV)

RHS Red Cherry cultivar page lists tomato spotted wilt virus among diseases tomato may be susceptible to.

Honey fungus

rare

Armillaria spp.

RHS Red Cherry cultivar page explicitly notes tomato is susceptible only "rarely".

Pests

Glasshouse red spider mite (two-spotted spider mite)

moderate_to_severe

Tetranychus urticae

RHS explicitly names tomato among confirmed host plants for glasshouse red spider mite. Source: RHS, "Glasshouse red spider mite,".

Glasshouse whitefly

common

Trialeurodes vaporariorum

RHS Red Cherry cultivar page: susceptible to glasshouse whitefly

Western flower thrips

variable_regional

Frankliniella occidentalis

Vector of Tomato spotted wilt virus; also a direct feeding pest independent of virus transmission.

Tomato moth (bright-line brown-eye)

common

Lacanobia oleracea

RHS Red Cherry cultivar page: susceptible to tomato moth

Nutrient Issues

Soil & Growing Conditions

Water: About 1 to 1.5 inches (25-38mm) of water per week (Ohio State Extension). Keep soil or compost evenly moist; container plants may need daily watering in hot weather (RHS).

Humidity: 60-70% RH is optimal for pollination (Alabama Cooperative Extension). Above ~80% RH pollen grains clump and pollination drops.

Soil pH range

5.8 6.8

Span reflects genuine variation between the cited authorities, not a single agreed figure.

Growth Stages

1. Establishment
2. Vegetative Growth
3. Flowering: Cordon types: side shoots removed as they appear; pinch growing tip after 7 trusses under cover or 4 outdoors (RHS).
4. Fruit Development
5. Ripening / Harvest: Killed by frost; cycle ends at first frost in UK outdoor/unheated conditions (tender perennial grown as annual).
6. Senescence / Dormancy: End-of-season unripe fruit can be lifted and ripened off the vine (RHS).

Harvest & Storage

When to pick: Tomatoes begin ripening from mid-summer; timing depends on variety, weather and fruit size (smaller cherry types ripen faster; greenhouse plants crop earlier and longer than outdoor). Check plants every few days and pick individually with the stalk attached as soon as fruit is ripe and fully coloured. At end of season, lift outdoor plants with unripe fruit and ripen on straw under cloches, or pick and ripen indoors in a warm dark place (e.g. a drawer with a banana).

Storage

Mature-green fruit: store at 55-70°F (12.8-21.1°C), 90-95% relative humidity, for 1-3 weeks. Firm-ripe fruit: same conditions but only 4-7 days (University of Maine Extension Bulletin #4135). Do not refrigerate unripe tomatoes - refrigeration inhibits ripening; ripen at about 70°F (21°C) instead, and refrigerating ripe fruit can reduce flavour and cause mealy texture (Clemson HGIC).

Companion Planting

French/Aztec marigold

pest deterrent

Tagetes erecta

Airborne limonene emitted by marigolds gives a negative behavioural response in glasshouse whitefly; season-long companion planting significantly slows whitefly population development on tomato (PLOS ONE glasshouse trial, 48-day infestation period).

Sweet basil

pest deterrent

Ocimum basilicum

Basil is a non-host plant for glasshouse whitefly; interplanting reduced proportion of marigolds with basil (plus nasturtium and Chinese cabbage) was also shown to reduce whitefly populations on tomato.

Strawberry

avoid shared disease

Fragaria x ananassa

Not a beneficial pairing -- this is a warning. Avoid planting strawberries in ground recently occupied by tomatoes, or the reverse, because both are highly susceptible to Verticillium wilt. RHS UK Advisory Service case records name both Fragaria and Solanum among the most frequently diagnosed…

Potato

avoid shared disease

Solanum tuberosum

Reuses the existing avoid_shared_disease relationship type (already used elsewhere in the graph). Sources: RHS potato-blight, RHS tomato-blight, RHS potato cyst nematodes, RHS potato-scabs.

Aubergine

avoid shared disease

Solanum melongena

Clemson HGIC gives a three-year solanaceous rotation for eggplant twice over: for bacterial wilt, "do not plant eggplant in areas that have had tomatoes, Irish potatoes, or eggplant planted in the previous three years"; and for southern blight, "avoid planting in areas where tomatoes, peppers,…

Pollination

Bumblebees (buzz pollinators) Bombus spp. (esp. B. terrestris, B. impatiens)

Tomato flowers are self-fertile and offer only pollen (no nectar reward). Outdoors, wind/vibration can trigger self-pollination; in the still air of a glasshouse this does not occur, so ~95% of commercial bumble bee colonies globally are used specifically in tomato greenhouses for buzz pollination (vibrating thoracic muscles to dislodge pollen). Bee pollination increases fruit set, yield and weight vs. other methods; honey bees cannot buzz-pollinate and do not reliably visit tomato flowers.

Sowing, Planting Out & Care

Sowing

1. Fill modules or small pots with good quality seed compost.
2. Sow 2 seeds per cell at 1cm depth, thinning to the strongest seedling.
3. Keep warm at 64-72°F (18-22°C) for germination (7–14 days).
4. Pot on when roots fill the module, into 7.5cm then 10cm pots.
5. Keep in bright light to prevent leggy growth.

Planting out and ongoing care

• Harden off gradually over 7–10 days before planting outside.
• Deep planting: bury the stem up to the first set of true leaves to encourage additional roots.
• Support: stake cordon varieties at planting; tie in regularly as they grow.
• Side shooting: remove side shoots on cordon (indeterminate) varieties weekly. Leave bush varieties unpruned.
• Feeding: begin weekly high-potassium liquid tomato feed once the first flowers appear; containers every 10–14 days once fruits swell.
• Watering: water consistently — irregular watering causes blossom end rot and splitting.
• Pinch out the growing tip in late summer to direct energy into ripening existing fruit.

Fruit Disorders to Watch For

These are physiological disorders rather than diseases: they are caused by growing conditions, not by a pathogen, so no spray will fix them and nothing is passed between plants.

• Splitting. Heavy rain after a dry spell causes fruits to split. Keep soil moisture even and harvest ripe fruits promptly.
• Greenback. A hard green patch at the top of the fruit, caused by excess sun or potassium deficiency. Choose resistant varieties and feed regularly.
• Blossom end rot. A dark, sunken patch at the base of the fruit — a calcium-transport problem driven by irregular watering, not a disease. See the Nutrient Issues section above.

Recommended Tools & Supplies

Having the right tools makes growing tomatoes easier. Our hand tools for gardening include precision secateurs ideal for removing side shoots and harvesting fruit, and the soil and plant care range covers everything from propagators to high-potassium feeds.

Planning the wider plot? See the UK vegetable planting calendar, or the monthly guides for March, April and May.

Sources

1. Alabama Cooperative Extension System - Greenhouse Tomato Production

   Pollinate when humidity is between 60 and 70 percent; day 80-85°F, night 60-65°F.

2. Clemson Cooperative Extension - Eggplant Insect Pests & Diseases

   Names Phytophthora blight, bacterial wilt, southern blight and Phomopsis blight as the diseases, and aphids/whiteflies, flea beetles, Colorado potato beetle, hornworms, stink and leaf-footed bugs, and spider mites as the pests, each with symptoms and management. Carries the three-year solanaceous rotation rule for both bacterial wilt and southern blight.

3. Clemson Cooperative Extension - Tomato

   Soil pH 6.0-6.5; best 70-80°F day / 60-70°F night; days to harvest 52-90 by cultivar; storage guidance.

4. NC State Extension - Solanum lycopersicum (Tomato)
5. Ohio State University Extension (Ohioline HYG-1624) - Growing Tomatoes in the Home Garden

   6-8 hours direct sun; pH 6.5-6.8; 1-1.5 inches water per week; ripening 68-77°F.

6. Penn State Extension - Tomato Production

   Soil pH 5.8-6.6; optimal 60-90°F, growth/pollination slows above 90°F or below 55°F.

7. University of California Statewide IPM Program (UC IPM) - Blossom End Rot / UC IPM Home and Landscape
8. University of California Statewide IPM Program (UC IPM) - Cucumber Mosaic — Cucurbits, Pest Management Guidelines
9. University of California Statewide IPM Program (UC IPM) - Tomato Spotted Wilt (Tomato PMG, UC ANR Pub 3470)

   Content dated 12/13.

10. University of Florida IFAS Extension - Tomatoes

    At least four to six hours of sun per day; pH 6.2-6.5. Florida climate context.

11. University of Maine Cooperative Extension (Bulletin #4135) - Storage Conditions: Fruits and Vegetables

    Tomato mature-green 55-70°F, 90-95% RH, 1-3 weeks; firm-ripe same conditions, 4-7 days.

12. University of Maryland Extension - Organic Matter and Soil Amendments

    Goal for vegetable and flower beds should be 5%-10% soil organic matter. General vegetable-bed guidance, not tomato-specific.

These 12 sources are specific to this region. The full list of 29 sources behind this guide (Alabama Cooperative Extension System, Clemson Cooperative Extension, Global Biodiversity Information Facility (GBIF) and others) is in the references of our UK guide to tomatoes; they describe the plant itself, which is the same wherever it grows.