Almost every companion planting chart on the internet was written for the temperate northeast: think Vermont, Pennsylvania, upstate New York. Tomato + basil + marigold. Three Sisters. Carrots + onions. The pairings work beautifully in zone 6 with a 150-day growing season and modest humidity. They quietly fail in Phoenix (everything bolts by April), Anchorage (the corn never ripens), or Miami (tomato leaves brown out in July humidity by 9 am). Your USDA Hardiness Zone is the single biggest variable in whether a companion plant chart helps or wastes your money.
This guide walks zone by zone, USDA Zone 3 to 11, with the companion pairings that actually work in each one and the famous ones that do not. Use it alongside the USDA Plant Hardiness Zone Map if you do not yet know your zone.
Key Takeaway
Companion planting advice that works in zone 6 (textbook northeast) often fails in zones 3-4 (too cold to ripen) and zones 8-11 (too hot for cool-season pairings). Adapt by tracking 4 variables: frost-free season length, summer heat, humidity, and day length. The universal pairings: diverse beds, nitrogen-fixing legumes, and tall-plus-short stacking. Find your zone at planthardiness.ars.usda.gov before you buy any seeds.
The same physical pairing produces different outcomes in different climates. Tomato and basil work brilliantly together in zone 6 New York: basil deters whitefly, both crops finish ripening before frost. Try the same pair in Tampa (zone 10), and basil thrives but the tomatoes succumb to bacterial wilt during the August rains. Farmers Almanac's companion planting guide and Bootstrap Farmer's pairings list are good northeast-temperate references; they need adaptation to most of the US.
Four climate variables drive most adaptations:
Why This Matters: Climate Is the Hidden Variable
Most gardening writing was developed in the temperate northeast US (zones 5-7) where the famous pairings emerged: tomato + basil, Three Sisters, carrots + onions. Those references treat their own climate as default. They are not wrong, just incomplete. Reading them as universal sets up cold-zone and hot-zone gardeners for repeated failure. Adapting by zone turns the same companion planting logic into a working system in your climate.
The USDA Plant Hardiness Zone Map divides the US into 13 zones by average annual minimum winter temperature, in 10 F bands. The current map (revised 2023) shows roughly half of US counties moved up by a half-zone since the previous 2012 release. UF/IFAS Duval County documents the recent shift in northeast Florida.
| Zone | Min winter temp | Representative US locations | Frost-free days |
| 3 | -40 to -30 F | Northern Minnesota, North Dakota, Interior Alaska | ~90-110 |
| 4 | -30 to -20 F | Anchorage, northern Maine, Iron Range Minnesota | ~110-130 |
| 5 | -20 to -10 F | Minneapolis, Burlington VT, Boise | ~140-160 |
| 6 | -10 to 0 F | Boston, Cleveland, Denver, Salt Lake City | ~160-180 |
| 7 | 0 to 10 F | NYC, Washington DC, Nashville, Albuquerque | ~180-210 |
| 8 | 10 to 20 F | Atlanta, Raleigh, Dallas, Portland OR | ~220-250 |
| 9 | 20 to 30 F | Houston, Phoenix, Jacksonville, central CA | ~250-300 |
| 10 | 30 to 40 F | South Florida, south Texas, coastal southern CA | ~330-365 |
| 11 | 40 to 50 F | Florida Keys, Hawaii | 365 (no frost) |
Source: USDA Plant Hardiness Zone Map
Anchorage, Fairbanks, Duluth, the Dakotas. 90-130 frost-free days. Tomatoes are marginal (need transplants and walls). Three Sisters does not finish ripening reliably (corn needs 100-110+ frost-free days for most varieties). Cold-tolerant Painted Mountain corn is a zone 4 workaround, but the rest of the Three Sisters timing is still tight.
What works:
Minneapolis, Burlington, Boise, Salt Lake. 140-160 frost-free days. The famous companion pairings now reliably finish. For Zone 5 food forest design see our Zone 5 food forest guide.
Boston, NYC, DC, Cleveland, Denver. 160-210 frost-free days. This is the climate the famous companion planting books were written in. Almost everything works.
For deeper companion planting guides, see our complete companion planting chart, what to plant with tomatoes, and the Three Sisters guide.
Atlanta, Raleigh, Dallas, Portland OR, Sacramento. 220-250 frost-free days. The big shift: lettuce, cilantro, peas, and spinach become winter crops. They bolt by May. Tomatoes have a spring season (March-June) and sometimes a fall season (September-November). Summer is brassica and lettuce dead time.
Houston, Phoenix, Jacksonville, central CA, southern Arizona. 250-300 frost-free days. Companion planting reorients around managing heat and humidity rather than cold. Reencle's zone 8b summer planting guide and Urban Farmer's zone 8 calendar are useful starting points; adapt to zone 9 by shifting timing 4-6 weeks earlier on the spring side.
For broader hot-climate context see our permaculture around the world overview.
South Florida, south Texas, southern California coast, Hawaii, Florida Keys. 330-365 frost-free days. The temperate seasonal-pairing model breaks down. Companion planting becomes permanent polyculture similar to Cuban organoponicos or food forest design.
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Subscribe FreePairings change. The underlying logic does not. Peer-reviewed research on trap cropping confirms three companion planting principles that work everywhere from zone 3 to zone 11:
Diversity reduces pest pressure
Monocultures attract specialised pest insects in dense waves. Even simple 3-species polycultures dilute pest detection by scent and visual confusion. A zone 3 cabbage + dill + nasturtium bed works for the same reason as a zone 11 banana + sweet potato + pigeon pea bed: diversity confuses pests.
Nitrogen fixers feed neighbors
Beans (zone 4-9), peas (zone 3-8), peanuts (zone 8-11), cowpeas / black-eyed peas (zone 7-11), pigeon peas (zone 9-11), clover (zone 3-9 as cover crop), favas (zone 5-9). Every climate has a legume that fixes 20-100 pounds of nitrogen per acre per season. Pair them with heavy feeders (corn, brassicas, tomatoes).
Tall + short stacking saves space
The Three Sisters (corn-beans-squash) and the banana-sweet-potato pairing are the same idea at different scales. Tall canopy plus medium climber plus ground cover plus root layer captures 3 to 4 production zones from the same square foot of soil.
Mistakes by Zone
Most companion planting failures come from applying advice written for one climate in a different one. The pairings are not wrong; the timing or species needs to shift.
Enter your zip code at the USDA Plant Hardiness Zone Map. The map shows your zone (3 to 11) and sub-zone (a or b). Updated in 2023. Roughly half of US counties shifted half a zone warmer between 2012 and 2023.
Four variables change by zone: frost-free season length (90 days in zone 3 vs 365 in zone 11), summer heat intensity (peak above 90 F or not), humidity (affects disease pressure), and day length (latitude affects bolting). The same pairing fails differently in each climate.
Zones 8-11 do best with heat-lovers planted together: okra, amaranth, sweet potato, black-eyed peas, pigeon peas, peppers, eggplant. Lettuce, peas, cilantro, and spinach are winter crops in these zones (October to April). Tomato + basil works in spring and fall, not summer.
Zones 3-5 do best with cool-season pairings: cabbage + dill + nasturtium; carrots + onions + lettuce; peas + spinach + strawberries. Three Sisters works in zone 5 with short-season corn varieties. Tomatoes need transplants and walls or row covers.
Yes, but the timing changes. Zones 5-7: plant after last frost, harvest June through September. Zone 8: spring (March-June) and fall (September-November), skipping peak July-August heat. Zone 9-10: late winter (February-April) and fall (September-December). Zone 11: October through April.
Probably yes. The USDA updated the Plant Hardiness Zone Map in 2023 based on 30 years of temperature data through 2020. UF/IFAS reports that roughly half of US counties shifted half a zone warmer. Recheck before relying on old companion planting calendars.
Marigolds. From Anchorage (zone 4) to Miami (zone 10), marigolds reliably repel nematodes, attract pollinators, and tolerate temperature swings. They are an annual everywhere outside zone 11, but cheap to reseed each year. They also work alongside almost every food crop.
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