USDA Hardiness Zone Planting Calendar: When to Plant Seeds by Zone
, by Seed World, 7 min reading time
Timing is everything in the garden. Use this USDA Hardiness Zone planting calendar to know exactly when to start seeds indoors, when to transplant, and when to direct sow — no matter where you live.
The most common reason a garden underperforms isn't the seeds — it's the timing. Plant too early and a late frost wipes out your seedlings. Plant too late and your crops don't have enough season to mature. The USDA Plant Hardiness Zone Map exists precisely to solve this problem, giving every gardener in the US a shared reference point for planting decisions.
Here's how to use it — and a full planting calendar broken down by zone.
What Are USDA Hardiness Zones?
The USDA Plant Hardiness Zone Map divides the US (and parts of Canada and Mexico) into 13 zones based on the average annual minimum winter temperature. Each zone spans a 10°F range, and most are further divided into "a" and "b" half-zones (5°F each).
Zone 1 covers the coldest regions (interior Alaska, average lows below -50°F). Zone 13 covers the warmest (parts of Hawaii and Puerto Rico, average lows above 60°F). Most of the contiguous US falls between Zones 3 and 10.
To find your zone: Visit the USDA Plant Hardiness Zone Map and enter your zip code.
Why Last Frost Date Matters More Than Zone Alone
Your zone tells you how cold your winters get. But for planting timing, the more useful number is your last spring frost date — the average date after which temperatures are unlikely to drop below 32°F (0°C).
Most planting calendars are built around this date, expressed as "X weeks before last frost" or "X weeks after last frost." Once you know yours, the calendar below becomes a precise planting guide for your specific location.
Planting Calendar by USDA Zone
Zones 3–4 (Minnesota, northern Wisconsin, Montana, northern Maine)
Last frost: Mid-May to early June | First fall frost: Early to mid-September
- Start indoors: February–March (tomatoes, peppers, eggplant, onions)
- Direct sow outdoors: Late May–June (beans, squash, cucumbers, corn)
- Cool-season crops: Direct sow as soon as soil is workable (April–May) — lettuce, spinach, peas, radishes, kale
- Fall planting: Limited season; focus on fast-maturing varieties (under 60 days)
Zones 5–6 (Chicago, New York, Denver, Portland OR)
Last frost: Mid-April to early May | First fall frost: Mid-October
- Start indoors: Late January–March (tomatoes, peppers, eggplant, herbs)
- Direct sow outdoors: After last frost (May) — beans, squash, cucumbers, sunflowers
- Cool-season crops: March–April outdoors; again in August for fall harvest
- Fall planting: Start brassicas, lettuce, and spinach in July–August for October harvest
Zones 7–8 (Virginia, Tennessee, Pacific Northwest, Georgia, Texas panhandle)
Last frost: Late March to mid-April | First fall frost: Late October–November
- Start indoors: January–February (tomatoes, peppers); earlier for heat-tolerant flowers
- Direct sow outdoors: April–May for warm-season crops; March for cool-season
- Summer gap: Skip planting in July–August for many crops (too hot); resume in late summer
- Fall/winter garden: Strong opportunity — plant brassicas, root vegetables, and greens September–October for winter harvest
Zones 9–10 (Southern California, Central Valley, South Florida, coastal Texas)
Last frost: Late January–February (or none) | First fall frost: December or none
- Cool-season crops: This is peak season — plant vegetables October through February for best results
- Warm-season crops: February–March (tomatoes, peppers, squash); avoid July–August peak heat
- Year-round gardening: Possible with heat-tolerant and cool-season varieties planted in rotation
- Tropical crops: Zone 10 can grow bananas, papayas, and other tropicals year-round
Quick Seed-Starting Reference by Crop
| Crop | Start Indoors | Transplant / Direct Sow | Days to Maturity |
|---|---|---|---|
| Tomato | 6–8 weeks before last frost | After last frost | 60–85 days |
| Pepper | 8–10 weeks before last frost | After last frost | 70–90 days |
| Cucumber | 3–4 weeks before last frost | After last frost | 50–70 days |
| Lettuce | 4–6 weeks before last frost | 4 weeks before last frost | 45–60 days |
| Squash | 2–3 weeks before last frost | After last frost | 50–65 days |
| Sunflower | Not recommended | After last frost | 70–100 days |
| Broccoli | 6–8 weeks before last frost | 3–4 weeks before last frost | 60–80 days |
| Basil | 6 weeks before last frost | After last frost (warm soil) | 60–90 days |
Choosing the Right Seeds for Your Zone
Zones with shorter growing seasons (3–5) benefit most from varieties bred for fast maturity — look for "early" designations and days-to-maturity under 70 days. Zones with longer seasons (8–10) have the luxury of growing slower-maturing, often more flavorful heirloom varieties.
Browse our NON-GMO & Organic Vegetable Seeds collection for a wide range of zone-appropriate varieties, or explore our Heirloom Seeds selection for open-pollinated classics that thrive in longer seasons.
Planning a spring planting? Our Spring Seeds Collection is curated for the most popular planting window across Zones 5–8.
Frequently Asked Questions
How do I find my USDA Hardiness Zone?
Enter your zip code at the official USDA Plant Hardiness Zone Map. Your zone and last frost date will appear instantly.
Is USDA zone the same as a planting zone?
Not exactly. USDA zones measure winter cold hardiness. Some gardeners also reference the Sunset Climate Zones (used mainly in the West) or AHS Heat Zones. For vegetable gardening, USDA zones combined with your local last frost date give the most actionable planting guidance.
Can I grow warm-season vegetables in Zone 4?
Yes — with a head start. Starting tomatoes, peppers, and squash indoors 6–10 weeks before your last frost date gives them enough time to produce before fall frost arrives. Choose fast-maturing varieties (under 70 days) for the best results in short-season zones.
What if I'm between two zones?
Use both as reference points. Microclimates within your yard (south-facing walls, raised beds, low-lying frost pockets) can shift your effective planting dates by 1–2 weeks in either direction. Track your own first and last frost dates over a few years for the most accurate local calendar.
Do flower seeds follow the same zone planting rules?
Generally yes, though many annual flowers are more frost-tolerant than vegetables. Hardy annuals like pansies and snapdragons can be planted several weeks before last frost; tender annuals like zinnias and marigolds go out after. Browse our Flower Seeds to Plant in Spring collection for zone-ready options.