Planting windows for Boulder
Computed from Boulder's own frost dates. Click any crop for the full zone-4 growing guide — varieties, spacing, fall plantings, and more.
| Crop | Start seeds indoors | Transplant | Direct sow |
|---|---|---|---|
| 🍅 Tomatoes | Apr 12 – Apr 26 | Jun 14 – Jun 21 | — |
| 🫑 Peppers | Mar 29 – Apr 12 | Jun 21 – Jun 28 | — |
| 🥬 Lettuce | Apr 26 – May 10 | May 10 – May 24 | May 10 – Jun 7 |
| 🫛 Peas | — | — | Apr 26 – May 10 |
| 🥕 Carrots | — | — | May 17 – Jun 7 |
| 🥦 Broccoli | Apr 19 – May 3 | May 17 – May 31 | — |
| 🥬 Kale | Apr 26 – May 10 | May 10 – May 24 | May 10 – May 24 |
| 🥒 Cucumbers | May 10 – May 17 | Jun 14 – Jun 21 | Jun 14 – Jun 21 |
| 🥒 Zucchini | May 10 – May 17 | Jun 14 – Jun 21 | Jun 14 – Jun 21 |
| 🫘 Green Beans (Bush) | — | — | Jun 14 – Jun 21 |
| 🌽 Sweet Corn | — | — | Jun 14 – Jun 21 |
| 🌿 Basil | Apr 26 – May 10 | Jun 14 – Jun 21 | Jun 21 – Jun 28 |
| 🧄 Garlic | — | — | Fall: Jul 28 – Aug 25 |
Want this for all 50 crops, or as a printable seed-shelf schedule? Use the planting calendar and the seed starting scheduler — both can use Boulder's dates automatically after a lookup.
Reading the season in Boulder
At about 93 frost-free days, Boulder rewards efficiency: start warm-season crops indoors, favor short-season varieties, and lean on cold-tolerant crops — peas, kale, roots — that shrug off the shoulder-season frosts on either end.