USDA Zone 5b Planting Calendar (2026)
Zone 5b (-15 to -10°F) has an average last spring frost on Apr 25 and first fall frost on Oct 10 — about 168 growing days. Typical areas: Denver CO, Columbus OH.
How to use the zone 5b planting calendar
Every planting date on this page is calculated from zone 5b's average frost dates. Because your last spring frost lands around Apr 25 and your first fall frost around Oct 10, you have roughly 168 frost-free days to work with — a moderate growing season. The table below lists, for each of 20 common vegetables, when to start seeds indoors, when to sow or transplant outdoors, and when you can expect your first harvest.
Frost dates are averages, not guarantees. In a cold year the last frost can arrive 1-2 weeks later, so keep row covers handy for tender seedlings in Apr. Click any vegetable name to open a detailed zone 5b guide with spacing, companions, container tips and troubleshooting.
Cool-season crops for zone 5b
These tolerate light frost and go out first, 2-4 weeks before your Apr 25 last frost, and again in late summer for a fall crop: lettuce, carrot, broccoli, spinach, kale, onion, garlic, potato, peas, radish, beet, cabbage, cauliflower.
Warm-season crops for zone 5b
These need warm soil and frost-free weather, so plant them after Apr 25: tomato, pepper, cucumber, corn, bush beans, summer squash, zucchini. In a moderate season, start the slowest ones indoors to be sure they ripen before Oct.
| Vegetable | Start Indoors | Sow / Transplant | Harvest From |
|---|---|---|---|
| Beet | — | Mar 28 | May 22 |
| 🥦 Broccoli | Mar 21 | Apr 11 | Jun 15 |
| 🫘 Bush Beans | — | May 2 | Jun 26 |
| 🥬 Cabbage | Mar 14 | Apr 11 | Jun 30 |
| 🥕 Carrot | — | Apr 4 | Jun 13 |
| 🥦 Cauliflower | Mar 14 | Apr 11 | Jun 25 |
| 🌽 Corn | — | May 9 | Jul 28 |
| 🥒 Cucumber | Apr 4 | May 9 | Jul 3 |
| 🧄 Garlic | — | Oct 10 | Jun 7 |
| 🥬 Kale | Mar 21 | Apr 4 | May 29 |
| 🥬 Lettuce | Mar 28 | Apr 4 | May 19 |
| 🧅 Onion | Feb 14 | Mar 28 | Jul 6 |
| 🟢 Peas | — | Mar 14 | May 13 |
| 🫑 Pepper | Feb 28 | May 9 | Jul 18 |
| 🥔 Potato | — | Apr 11 | Jul 10 |
| 🌶️ Radish | — | Mar 28 | Apr 25 |
| 🍃 Spinach | — | Mar 21 | Apr 30 |
| 🎃 Summer Squash | Apr 4 | May 2 | Jun 21 |
| 🍅 Tomato | Mar 14 | May 2 | Jul 16 |
| 🥒 Zucchini | Apr 4 | May 2 | Jun 21 |
Spring, summer and fall planting in zone 5b
Spring (Apr): As soon as the soil can be worked, direct sow hardy cool-season crops and set out frost-tolerant transplants. This is your window for peas, lettuce, spinach and the brassicas before summer heat arrives.
Early summer (after Apr 25): Once frost danger passes and soil warms past 60°F, transplant tomatoes, peppers and squash and direct sow beans and cucumbers. This is the heart of the zone 5b growing season.
Late summer to fall (before Oct 10):Sow a second round of quick cool-season crops for a fall harvest. Count back each crop's days-to-harvest from Oct 10 to find the latest safe sowing date, and use row covers to stretch the season a few extra weeks.
Zone 5b planting FAQ
What planting zone is Denver CO?
Areas like Denver CO, Columbus OH fall in USDA hardiness zone 5b, defined by an average annual minimum temperature of -15 to -10°F. Your average last spring frost is around Apr 25 and your first fall frost around Oct 10.
When is the last frost in zone 5b?
The average last spring frost in zone 5b is around Apr 25. Wait until after this date before transplanting warm-season crops like tomatoes, peppers and squash. Cool-season crops can go out 2-4 weeks earlier because they tolerate light frost.
How long is the growing season in zone 5b?
Zone 5b has roughly 168 frost-free days between the last spring frost (Apr 25) and first fall frost (Oct 10). That is a moderate season — enough time for most vegetables plus some succession planting.
What vegetables grow best in zone 5b?
Reliable choices for zone 5b include cool-season crops such as lettuce, carrot, broccoli, spinach planted in early spring, and warm-season crops such as tomato, pepper, cucumber, corn planted after the last frost. See the full table below for exact dates.
Can I grow a fall garden in zone 5b?
Yes. With a first frost around Oct 10, you can plant a second round of quick cool-season crops in mid to late summer. Count back the days-to-harvest from Oct 10 to find your fall planting date.
When should I start seeds indoors in zone 5b?
Most warm-season seedlings are started indoors 6-8 weeks before the last frost — that means roughly Apr for zone 5b. Tomatoes, peppers and eggplant benefit most from an indoor head start in this zone.