Planting Calendar for ZIP 80603
Based on your local frost dates - last spring frost around May 5, first fall frost around Oct 9 - here is when to plant 79 common crops near ZIP 80603.
Last spring frost
May 5
First fall frost
Oct 9
Hardiness zone
5b
Vegetables
| Crop | Start seeds indoors | Plant outside | Fall planting by |
|---|---|---|---|
| Tomatoes | Mar 24 | May 12 (Transplant out) | - |
| Peppers | Mar 10 | May 19 (Transplant out) | - |
| Cucumbers | Apr 14 | May 12 (Transplant out) | Aug 1 |
| Zucchini | Apr 14 | May 12 (Transplant out) | Aug 6 |
| Summer Squash | Apr 14 | May 12 (Transplant out) | Aug 4 |
| Winter Squash | Apr 14 | May 12 (Transplant out) | - |
| Pumpkins | Apr 14 | May 12 (Transplant out) | - |
| Green Beans | - | May 5 (Direct sow) | Aug 1 |
| Sweet Corn | - | May 12 (Direct sow) | - |
| Melons | Apr 14 | May 19 (Transplant out) | - |
| Watermelon | Apr 14 | May 19 (Transplant out) | - |
| Okra | - | May 19 (Direct sow) | - |
| Eggplant | Mar 10 | May 19 (Transplant out) | - |
| Lettuce | Apr 7 | Apr 7 (Transplant out) | Aug 6 |
| Spinach | - | Mar 24 (Direct sow) | Aug 11 |
| Kale | Mar 24 | Apr 14 (Transplant out) | Aug 1 |
| Peas | - | Mar 24 (Direct sow) | Jul 27 |
| Carrots | - | Apr 14 (Direct sow) | Jul 17 |
| Beets | - | Apr 7 (Direct sow) | Aug 1 |
| Radishes | - | Apr 7 (Direct sow) | Aug 28 |
| Broccoli | Mar 24 | Apr 21 (Transplant out) | Jul 22 |
| Cauliflower | Mar 24 | Apr 21 (Transplant out) | Jul 17 |
| Cabbage | Mar 24 | Apr 14 (Transplant out) | Jul 17 |
| Onions | Feb 24 | Apr 7 (Transplant out) | - |
| Potatoes | - | Apr 21 (Direct sow) | - |
| Swiss Chard | Apr 7 | Apr 21 (Transplant out) | Aug 1 |
| Sweet Potatoes | - | May 26 (Direct sow) | - |
| Brussels Sprouts | Mar 24 | Apr 21 (Transplant out) | Jun 17 |
| Celery | Feb 24 | May 12 (Transplant out) | - |
| Leeks | Feb 24 | Apr 21 (Transplant out) | May 28 |
| Turnips | - | Apr 21 (Direct sow) | Aug 6 |
| Rutabaga | - | May 5 (Direct sow) | Jun 22 |
| Parsnips | - | Apr 21 (Direct sow) | May 28 |
| Kohlrabi | Apr 7 | Apr 21 (Transplant out) | Aug 1 |
| Collard Greens | Mar 24 | Apr 21 (Transplant out) | Jul 22 |
| Mustard Greens | - | Apr 21 (Direct sow) | Aug 11 |
| Arugula | - | Apr 21 (Direct sow) | Aug 16 |
| Bok Choy | Apr 7 | Apr 21 (Transplant out) | Aug 6 |
| Green Onions | - | Apr 21 (Direct sow) | Jul 27 |
| Tomatillos | Mar 24 | May 12 (Transplant out) | - |
| Fennel | Apr 7 | Apr 21 (Transplant out) | Jul 7 |
| Popcorn | May 5 | May 19 (Transplant out) | - |
| Black-Eyed Peas | May 5 | May 19 (Transplant out) | Jul 7 |
| Lima Beans | May 5 | May 19 (Transplant out) | - |
| Edamame | May 5 | May 19 (Transplant out) | - |
| Peanuts | May 5 | May 19 (Transplant out) | - |
| Globe Artichoke | Mar 10 | Apr 21 (Transplant out) | Jun 27 |
| Horseradish | May 5 | Apr 21 (Transplant out) | - |
| Ground Cherries | Mar 24 | May 19 (Transplant out) | - |
| Radicchio | Mar 31 | Apr 21 (Transplant out) | Jul 17 |
| Endive | Mar 31 | Apr 21 (Transplant out) | Jun 27 |
| Watercress | Apr 14 | Apr 21 (Transplant out) | Jul 27 |
| Sorrel | Mar 24 | Apr 14 (Transplant out) | Jul 27 |
| Sunchokes | May 5 | Apr 21 (Transplant out) | - |
| Malabar Spinach | Mar 24 | May 19 (Transplant out) | - |
| Amaranth Greens | Apr 14 | May 19 (Transplant out) | Aug 11 |
| Luffa Gourd | Mar 24 | May 19 (Transplant out) | - |
| New Zealand Spinach | Apr 7 | May 19 (Transplant out) | - |
| Fava Beans | May 5 | Apr 7 (Transplant out) | Jul 2 |
| Chayote | Apr 7 | May 19 (Transplant out) | - |
| Corn Salad | May 5 | Apr 7 (Transplant out) | Jul 27 |
| Bitter Melon | Apr 7 | May 19 (Transplant out) | - |
| Cardoon | Mar 24 | May 5 (Transplant out) | - |
Herbs
| Crop | Start seeds indoors | Plant outside | Fall planting by |
|---|---|---|---|
| Basil | Mar 24 | May 12 (Transplant out) | - |
| Cilantro | - | Apr 21 (Direct sow) | Aug 6 |
| Parsley | Mar 10 | May 19 (Transplant out) | Jul 12 |
| Dill | - | May 12 (Direct sow) | Jul 27 |
| Lemon Balm | Mar 24 | May 5 (Transplant out) | - |
| Borage | May 5 | May 5 (Transplant out) | Aug 1 |
| Chervil | May 5 | Apr 14 (Transplant out) | Aug 1 |
| Lemongrass | Mar 10 | May 19 (Transplant out) | - |
| Summer Savory | Mar 24 | May 5 (Transplant out) | - |
| Marjoram | Mar 24 | May 12 (Transplant out) | - |
| Lovage | Mar 24 | May 5 (Transplant out) | Jun 27 |
| Anise Hyssop | Mar 10 | May 5 (Transplant out) | - |
| Shiso | Mar 24 | May 12 (Transplant out) | - |
| Stevia | Mar 10 | May 19 (Transplant out) | - |
| Chamomile | Mar 24 | Apr 21 (Transplant out) | Jul 22 |
| Tarragon | May 5 | May 5 (Transplant out) | - |
How to read this calendar
Start seeds indoors is when to sow in trays inside so seedlings are ready to transplant. Plant outside is when to transplant seedlings or direct-sow seed, based on frost tolerance. Fall planting by is the latest date to start a fall crop and still harvest before the first fall frost. Tender crops wait until after the last spring frost; hardy crops can go out earlier.
Computed from NOAA 1991–2020 Climate Normals at Denver Intl Ap, Co, 8.2 miles away. Averages for planning, not a forecast. Page updated Aug 4, 2026.