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When to plant tomatoes

Nightshades, Solanum lycopersicum

Spacing
24″ apart
Per sq ft
1
To harvest
60–85 days
Frost
Tender

Companion plants for tomatoes

What to grow next to tomatoes, what to keep away, and what is only tradition. Every pairing says how strong the evidence is.

Grow together 8

Helps, or shares the bed well.

  • Basil Mixed The classic pairing. A few trials found fewer whiteflies or thrips on tomatoes grown with basil; others found no difference. Both like the same heat and water, so they grow well together either way.

    Basil guide

  • Marigold Mixed French marigolds suppress root-knot nematodes only when grown densely as a cover crop for two months or more before tomatoes. A few marigolds dotted between tomatoes does little.

    Source: Marigolds (Tagetes spp.) for Nematode Management (ENY-056), Krueger, Dover, McSorley & Wang, University of Florida IFAS Extension. Marigold guide

  • Nasturtium Mixed Nasturtiums attract aphids and can act as a trap crop, but only if you deal with the aphids on them. Otherwise they become an aphid nursery.

    Source: Trap cropping: a review of the state of the art, Sarkar et al., 2018 (open-access review). Nasturtium guide

  • Lettuce Practical Lettuce fills the bare soil around young tomatoes and is picked before the tomatoes shade it out. Later, the tomatoes give lettuce welcome afternoon shade.

    Lettuce guide

  • Red leaf lettuce Practical Lettuce fills the bare soil around young tomatoes and is picked before the tomatoes shade it out. Later, the tomatoes give lettuce welcome afternoon shade.

    Red leaf lettuce guide

  • Parsley Practical Flowering herbs and annuals feed hoverflies, lacewings and parasitic wasps that eat aphids and caterpillars on tomatoes.

    Source: Gardening with Companion Plants (EM128E), Linda Chalker-Scott, Washington State University Extension, 2023. Parsley guide

  • Calendula Practical Flowering herbs and annuals feed hoverflies, lacewings and parasitic wasps that eat aphids and caterpillars on tomatoes.

    Source: Gardening with Companion Plants (EM128E), Linda Chalker-Scott, Washington State University Extension, 2023. Calendula guide

  • Zinnia Practical Flowering herbs and annuals feed hoverflies, lacewings and parasitic wasps that eat aphids and caterpillars on tomatoes.

    Source: Gardening with Companion Plants (EM128E), Linda Chalker-Scott, Washington State University Extension, 2023. Zinnia guide

Keep apart 3

Shared pests, disease or competition.

  • Potato Practical Both get early blight and late blight. Planting them side by side lets disease move between them and makes rotation harder.

    Potato guide

  • Sweet corn Practical The corn earworm is the same insect as the tomato fruitworm. A corn patch next to tomatoes feeds both stages of the same pest.

    Sweet corn guide

  • Strawberry Practical Nightshades carry verticillium wilt, a soil disease that also kills strawberries. Don’t plant strawberries where nightshades grew in the last 3–4 years.

    Strawberry guide

Tradition only 8

On many charts, with little or no evidence.

  • Carrot Tradition Said to help “Carrots love tomatoes” is a famous book title, not a research finding. They don’t compete much, which is the real reason it works.

    Carrot guide

  • Chives Tradition Said to help Often said to repel pests by smell. Field research has not shown aromatic plants repel garden pests; they simply fit in the gaps.

    Source: Gardening with Companion Plants (EM128E), Linda Chalker-Scott, Washington State University Extension, 2023. Chives guide

  • Onion Tradition Said to help Often said to repel pests by smell. Field research has not shown aromatic plants repel garden pests; they simply fit in the gaps.

    Source: Gardening with Companion Plants (EM128E), Linda Chalker-Scott, Washington State University Extension, 2023. Onion guide

  • Garlic Tradition Said to help Often said to repel pests by smell. Field research has not shown aromatic plants repel garden pests; they simply fit in the gaps.

    Source: Gardening with Companion Plants (EM128E), Linda Chalker-Scott, Washington State University Extension, 2023. Garlic guide

  • Broccoli Tradition Said to harm Many charts say brassicas stunt tomatoes. There is no good evidence for it; the real issue is that both are big, hungry plants competing for space.

    Broccoli guide

  • Cauliflower Tradition Said to harm Many charts say brassicas stunt tomatoes. There is no good evidence for it; the real issue is that both are big, hungry plants competing for space.

    Cauliflower guide

  • Cabbage Tradition Said to harm Many charts say brassicas stunt tomatoes. There is no good evidence for it; the real issue is that both are big, hungry plants competing for space.

    Cabbage guide

  • Dill Tradition Said to harm Mature dill is said to stunt tomatoes. There is no research behind it, and young dill flowers attract beneficial insects.

    Dill guide

Studied Field or lab research shows an effect, at least under some conditions.
Mixed Some studies find an effect, others don’t, or it only works in a narrow way.
Practical Explained by light, space, timing, support or a shared pest or disease.
Tradition Widely repeated, but with little or no evidence behind it.

See every pairing side by side in the companion planting chart, or try them in a bed with the garden planner.

When to plant tomatoes by city

Start tomatoes indoors 6–8 weeks before your last frost, plant them out 1–3 weeks after your last frost, once the soil is at least 60°F. Here is what that means for 2027 in cities across the US, using each city’s average frost dates and the date its normal daily temperature reaches 60°F, so cool-spring places like Seattle wait for real warmth (NOAA 1991–2020). Pick the city with the climate most like yours, or enter your ZIP code above.

City Last frost Start indoors Plant out
Seattle, WA (9a) Mar 13 Mar 27 – Apr 10 May 29 – Jun 12
Portland, OR (8b) Feb 25 Mar 22 – Apr 5 May 24 – Jun 7
Sacramento, CA (9b) Jan 12 Feb 1–15 Apr 5–19
Phoenix, AZ (10a) Jan 5 Dec 14–28 Feb 15 – Mar 1
Salt Lake City, UT (7b) Mar 31 Mar 6–20 May 8–22
Denver, CO (6a) Apr 30 Mar 15–29 May 17–31
Dallas, TX (8b) Mar 2 Jan 13–27 Mar 17–31
Minneapolis, MN (5a) Apr 23 Mar 17–31 May 19 – Jun 2
Kansas City, MO (6b) Apr 4 Feb 21 – Mar 7 Apr 25 – May 9
Chicago, IL (6b) Apr 10 Mar 20 – Apr 3 May 22 – Jun 5
Columbus, OH (6b) Apr 20 Mar 5–19 May 7–21
Nashville, TN (7b) Apr 1 Feb 12–26 Apr 16–30
Atlanta, GA (8a) Mar 24 Feb 4–18 Apr 8–22
Raleigh, NC (8a) Mar 28 Feb 9–23 Apr 13–27
Philadelphia, PA (7b) Mar 30 Feb 23 – Mar 9 Apr 27 – May 11
Boston, MA (7a) Apr 4 Mar 18 – Apr 1 May 20 – Jun 3

In frost-free parts of Florida, southern California and the Gulf Coast, timing is about heat instead: plant tomatoes in late winter or early spring and again in late summer.

Don’t go by the calendar alone. Tomatoes planted into cold soil sit still for weeks; wait until the soil 4 inches down is at least 60°F and nights stay above 50°F.

Tomato spacing

In a square-foot bed, plant 1 per square foot, growing them up a trellis or cage. In traditional rows, space plants about 24 inches apart with 36 inches between rows.

Stake or cage it to grow one per square. Plant deep: roots form along the buried stem.

One square foot planted with tomatoes, as drawn in the planner.

How to grow tomatoes

Tomatoes are the crop most American gardeners grow first, and a few healthy plants can supply fruit from midsummer to frost. They want heat, steady water and something to climb, so they suit anyone willing to stake plants and check on them a couple of times a week.

Sun and soil

Full sun, 6–8 hours or more. Deep, well-drained soil rich in organic matter, pH about 6.0–6.8. Water deeply, 1–2 inches a week.

Planting

  1. Sow seeds ¼ inch deep indoors 6–8 weeks before the last frost, at about 80°F.
  2. Transplant 1–3 weeks after the last frost, once soil is 60°F and nights stay above 50°F.
  3. Bury the stem so only the top 2–3 sets of leaves show; roots form along the buried part.
  4. Space 24 inches apart in rows 36 inches apart, or one per square foot if staked and pruned. Set supports at planting.

Care

  • Keep moisture even and mulch once the soil is warm; wet-dry swings cause blossom-end rot and cracking.
  • Side-dress with a little nitrogen about 4 and 8 weeks after transplanting. Too much gives leaves, not fruit.
  • On staked plants, remove suckers weekly and tie the stem every 10 inches or so.

Harvest

Pick when fully colored but still slightly firm, about 25–35 days after flowering. Store on the counter, not in the refrigerator. Before frost, bring in mature green fruit to ripen at about 70°F.

Common problems

  • Blossom-end rot: A sunken, leathery patch on the fruit bottom from uneven watering. Water evenly, mulch, and go easy on nitrogen.
  • Early blight and Septoria leaf spot: Spots on lower leaves that climb upward. Remove spotted leaves, mulch, water at the base, and rotate nightshades for 3 years.
  • Tomato hornworm: Big green caterpillars. Hand-pick; leave any carrying white wasp cocoons. Bt controls young larvae.

Varieties to try

  • 'Celebrity' — determinate red slicer, broad disease resistance
  • 'Big Beef' — large, reliable indeterminate hybrid
  • 'Brandywine' — heirloom pink beefsteak, rich flavor, late
  • 'San Marzano' — paste tomato for sauce

Crop rotation

Tomatoes belong to the nightshades (Solanaceae). Heavy feeders that share blights and soil pests. Rotate out for 3–4 years. Relatives that count as the same family for rotation: cherry tomato, bell pepper, hot pepper, eggplant, potato.

Frequently asked questions

When should I plant tomatoes?
Start tomatoes indoors 6–8 weeks before your last frost, plant them out 1–3 weeks after your last frost, once the soil is at least 60°F. Type your ZIP code above for exact dates, or see the city table.
What grows well with tomatoes?
Good neighbors for tomatoes include basil, marigold, nasturtium, lettuce, red leaf lettuce and parsley. Each one is listed above with the reason and how strong the evidence is.
What should not be planted with tomatoes?
Keep tomatoes apart from potato, sweet corn and strawberry. Both get early blight and late blight. Planting them side by side lets disease move between them and makes rotation harder.
How far apart should I plant tomatoes?
In rows, space tomatoes about 24 inches apart with rows 36 inches apart. In a square-foot bed, plant 1 per square foot. That density assumes they grow up a trellis or cage.
How long do tomatoes take to grow?
About 60–85 days from planting out transplants to first harvest, depending on the variety and the weather.
Can tomatoes handle frost?
No. Tomatoes are killed by frost and sulk in cold soil, so wait until after your last frost and until the soil reaches about 60°F.

Sources

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