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Tomatoes

When to start, transplant and harvest tomatoes, as 6 university extension services put it, and what that means in each zone.

Family
Solanaceae5
Type
Fruiting
Rules
8
Last reviewed
Garden experts do not always agree, so I show every rule side by side.

Five digits. The calendar is computed on your device.

Spring timing, source by source

Every rule counts from the last spring frost, so the same rule gives different dates in different gardens. Here are the rules themselves before any dates are worked out.

  1. Colorado StateTransplant outdoors
  2. Utah StateTransplant outdoors
  3. Oregon State, central ORTransplant outdoors
  4. Oregon State, central ORStart indoors
  5. Texas A&M (E-502)Transplant outdoors
  • Plant outdoors
  • Start indoors
Figure 1. How each extension source times tomatoes in spring, in weeks before or after the last frost. Sources disagree; each bar is one publication's rule, shown as written.

Fall timing, source by source

Fall rules count from the first fall frost.

  1. Texas A&M (E-502)Plant for fall
  • Plant outdoors
Figure 2. How each extension source times tomatoes in fall, in weeks before or after the first frost. Rules written for warm states sit weeks earlier than those for cold ones.
Table 1. Planting rules for tomatoes, as published.
SourceWritten forWhatWhen
Colorado State1COTransplant outdoors2 weeks after last frost
Utah State2UTTransplant outdoors2 weeks after last frost
Oregon State, central OR11central OregonTransplant outdoorsOn the last frost
Oregon State, central OR11central OregonStart indoors8 weeks before last frost
Texas A&M (E-502)4TXTransplant outdoors1-8 weeks after last frost
Texas A&M (E-502)4TXPlant for fall12-14 weeks before first frost
Nebraska (G1343)12NEPlant for fallCount back days to maturity + 14-day fall factor (+14 for tender crops) from the first frost

Tomatoes by hardiness zone

Applied to the frost records of every ZIP in each zone. The zone median is a starting point; your own station can be weeks earlier or later.

Table 2. Outdoor planting for tomatoes by zone, using the Colorado State rule. Linked zones have their own page.
ZoneWhatZone medianAcross most of the zone
4aTransplant outdoorsMay 26May 19 – Jun 7
4bTransplant outdoorsMay 22May 15 – Jun 8
5aTransplant outdoorsMay 17May 10 – Jun 3
5bTransplant outdoorsMay 15May 5 – May 31
6aTransplant outdoorsMay 12Apr 30 – May 24
6bTransplant outdoorsMay 6Apr 24 – May 17
7aTransplant outdoorsApr 30Apr 18 – May 12
7bTransplant outdoorsApr 19Apr 13 – May 1
8aTransplant outdoorsApr 12Apr 3 – Apr 21
8bTransplant outdoorsMar 31Mar 20 – Apr 15
9aTransplant outdoorsMar 16Mar 1 – Apr 1

Growing facts

Table 3. Each value as one source states it. Sources measure differently, so values are not averaged.
FactValueSource
Frost tolerancevery tenderColorado State1
Frost tolerancevery tenderUtah State2
Frost tolerancetenderPurdue (HO-66)3
Minimum soil temperature50°FColorado State1
Best soil temperature80°FColorado State1
Days to germinate6-14 daysColorado State1
Days to germinate6-12 daysTexas A&M (E-502)4
Days to maturity65 days from transplantColorado State1
Days to maturity70-90 days from plantingTexas A&M (E-502)4
Days to maturity90-110 days from seedUF/IFAS Florida5
Days to maturity70-90 days from transplantUF/IFAS Florida5
Days to maturity50-120 days from plantingArizona (AZ1005)6
Spacing24 in apart each wayColorado State1
Spacing36-48 in in the row, rows 36-48 in apartTexas A&M (E-502)4
Spacing18-32 in in the row, rows 48 in apartUF/IFAS Florida5
Spacing24-48 in in the row, rows 48-60 in apartTexas A&M (E-517)7
Heat limit90°Fncsu-hoke-tired-tomatoes8
Heat limit90°Fncsu-burke-blossom-drop9
Heat limit90°Fpurdue-hot-weather10

Companions, and how sure anyone is

  • Basil · Disputed Tested in a study

    Claims: basil raises combined yield, improves tomato flavour and masks tomatoes from thrips and hornworms. Garden-scale trials found no consistent flavour effect and mixed yield results.131313141415151617

    Bomford 2004 thesis (not peer reviewed): basil companions gave a mean 20% relative-yield advantage, largest at high density and high basil share; no consistent taste preference. Bomford & Butler 2003 abstract: no LER significantly above 1; tomato pests did not respond. Penn State says basil masks tomatoes from thrips and hornworms but cites no study. Conboy 2019 (glasshouse): a marigold mix that included basil reduced whitefly; basil alone untested.

  • Marigold · Helps Tested in a study

    French marigold grown alongside tomato slowed glasshouse whitefly build-up (airborne limonene). Marigold grown before tomato reduced root-knot nematode galling in the following tomato crop.16181819191917

    Whitefly: glasshouse trials with marigolds present all season; adding them after whitefly build-up gave minimal reduction (Conboy 2019). Nematodes: only as a cover crop planted at least 2 months before, on the same site, in soil above 15 °C, with a resistant cultivar (Ploeg & Maris 1999; UF/IFAS ENY-056). Interplanting for nematodes is "probably not" effective, and marigold increases some nematodes (ENY-056).

  • Potatoes · Avoid together Extension guidance

    Shared late blight: the pathogen overwinters mainly on infected potato tubers and spreads by wind to nearby tomatoes.20201717

    WSU HortSense advises against planting the two close together. The UC tradition chart also lists them as incompatible (without giving a reason); we did not find a field study of planting distance.

  • Fennel · Avoid together Traditional pairing17

  • Carrots · Helps Traditional pairing17

  • Onions · Helps Traditional pairing17

    The chart says "onion family".

  • Garlic · Helps Traditional pairing17

    The chart says "onion family"; garlic is an onion-family (Allium) crop.

  • Cucumbers · Helps Traditional pairing17

  • Nasturtium · Helps Traditional pairing1716

    In Conboy 2019 glasshouse trials a marigold mix that also held basil, nasturtium and Chinese cabbage reduced whitefly on tomato; nasturtium alone was not tested.

Traditional pairings come from a UC Master Gardener chart that traces to the UC Davis Edible Landscaping Handbook and ATTRA. The chart gives no reasons, and we found no trial of these pairs; treat them as garden lore.

All tomatoes companions, with sources · The full companion chart

Sources

  1. Colorado State University Extension, Vegetable Planting Guide (CMG GardenNotes #720), reviewed September 2024. Retrieved 2026-11-02.
  2. Utah State University Extension, Suggested Vegetable Planting Dates for Utah, January 2018; revised May 2025. Retrieved 2026-11-02.
  3. Purdue Extension, The Fall Vegetable Garden (HO-66-W), reviewed September 2019. Retrieved 2026-11-02.
  4. Texas AgriLife Extension Service, The Texas A&M System, Texas Home Vegetable Gardening Guide (E-502), 2/09. Retrieved 2026-11-02.
  5. University of Florida, IFAS Extension (Department of Horticultural Sciences), Florida Vegetable Gardening Guide (SP 103 / VH021), Original December 1999; revised October 2015, January 2016, May 2018, September 2020, September 2021, and June 2025. Retrieved 2026-11-02.
  6. The University of Arizona Cooperative Extension, Vegetable Planting Calendar for Maricopa County (AZ1005), reviewed This information has been reviewed by University faculty.. Retrieved 2026-11-02.
  7. Texas AgriLife Extension Service, The Texas A&M System, Easy Gardening: Tomatoes (E-517), 08-09. Retrieved 2026-11-02.
  8. N.C. Cooperative Extension, Hoke County Center, Tired Summer Tomatoes, 2025-07-16. Retrieved 2026-11-02.
  9. N.C. Cooperative Extension, Burke County Center, Blossom Drop, 2021-07-01. Retrieved 2026-11-02.
  10. Purdue University, Indiana Yard and Garden (Purdue Consumer Horticulture), Hot Weather Is Tough on Plants Too!, reviewed Page last modified October 26, 2016. Retrieved 2026-11-02.
  11. Oregon State University Extension Service, When to start seeds indoors in central Oregon, reviewed 2024. Retrieved 2026-11-02.
  12. University of Nebraska–Lincoln Extension, Fall Vegetable Gardening (NebGuide G1343), Revised March 2012. Retrieved 2026-11-02.
  13. West Virginia University, Plant and Soil Science (Ph.D. thesis); record on Organic Eprints, Yield, pest density, and tomato flavor effects of companion planting in garden-scale studies incorporating tomato, basil, and Brussels sprout, 2004 (deposited 19 Dec 2005). Retrieved 2026-11-02.
  14. Meeting abstract (ASA-CSSA-SSSA 2003 annual meetings abstracts collection, mirrored by Prince of Songkla University library), Do Tomatoes Love Basil But Hate Brussels Sprouts? Evaluating Popular Companion Planting Claims in Garden-Scale Studies (NE_05-bomford156693-oral), 2003. Retrieved 2026-11-02.
  15. Penn State Extension, Herbs Make Good Plant Partners and Companions, Updated April 22, 2026. Retrieved 2026-11-02.
  16. PLOS ONE 14(3): e0213071, Companion planting with French marigolds protects tomato plants from glasshouse whiteflies through the emission of airborne limonene, March 1, 2019. Retrieved 2026-11-02.
  17. University of California Agriculture and Natural Resources (UCCE Master Gardener Program), Companion Planting Chart: Companion planting in the vegetable garden, File dated 2023-09 in URL path; no date printed. Retrieved 2026-11-02.
  18. Journal of Nematology 31(4S):709-714 (Society of Nematologists); PMC2620405, Effect of Temperature on Suppression of Meloidogyne incognita by Tagetes Cultivars, December 1999. Retrieved 2026-11-02.
  19. University of Florida, IFAS Extension (Entomology and Nematology Department), Marigolds (Tagetes spp.) for Nematode Management (ENY-056), reviewed Reviewed November 2019; page footer "Reviewed: 01/2024". Retrieved 2026-11-02.
  20. Washington State University Extension (HortSense), Tomato: Late blight (HortSense fact sheet), reviewed Last review date: 2026-08-28. Retrieved 2026-11-02.