Frost Dates & Planting Calendar for Commerce City, CO
Plan your garden around Commerce City, CO's typical frost-free growing season, using NOAA climate normals and a 42-crop planting calendar built for this location.
Last Spring Frost
May 4
Safe May 16
Typical May 4
Risky Apr 20
First Fall Frost
October 8
Safe Sep 25
Typical Oct 8
Risky Oct 20
Growing Season
156 days
Typical last frost to typical first frost.
USDA Hardiness Zone
Zone 6a
A classic four-season climate with cold winters and a solid summer growing season.
Data: NOAA station DENVER-STAPLETON, CO US, 7.4 km away.
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days until the typical last spring frost
Monthly Temperatures
Avg. high
Avg. temp
Avg. low
Planting Calendar
| Crop | Start indoors | Direct sow | Transplant | Fall planting | Maturity | Notes |
|---|---|---|---|---|---|---|
| Tomato | Mar 9 – Mar 23 | — | May 11 – May 18 | — | 60–85 days | Start indoors 6-8 weeks before last frost; transplant out 1-2 weeks after last frost once soil has warmed. |
| Pepper | Feb 23 – Mar 9 | — | May 11 – May 25 | — | 60–90 days | Slow to germinate; start indoors 8-10 weeks before last frost. Transplant only once nights stay above 55F, 1-3 weeks after last frost. |
| Eggplant | Feb 23 – Mar 9 | — | May 18 – May 25 | — | 65–85 days | Warm-season crop, similar timing to pepper; needs consistently warm soil (65F+) to transplant. |
| Cucumber | Apr 6 – Apr 13 | May 11 – May 18 | May 11 – May 18 | — | 50–65 days | Can be started indoors 3-4 weeks before transplanting, or direct-sown 1-2 weeks after last frost once soil is warm. |
| Zucchini | Apr 13 – Apr 20 | May 11 – May 25 | May 11 – May 18 | — | 45–55 days | Fast-growing squash; direct sow 1-3 weeks after last frost, or start indoors 2-3 weeks early for a head start. |
| Winter Squash | Apr 6 – Apr 13 | May 11 – May 25 | May 11 – May 18 | — | 80–110 days | Long season; direct sow after soil warms, or start indoors 3-4 weeks before last frost in short-season climates. |
| Pumpkin | — | May 11 – May 25 | — | — | 90–120 days | Direct sow 1-3 weeks after last frost; back-time from your first fall frost so the 90-120 day maturity window lands before it. |
| Watermelon | Apr 6 – Apr 13 | — | May 18 – May 25 | — | 70–90 days | Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost. |
| Cantaloupe | Apr 6 – Apr 13 | — | May 18 – May 25 | — | 70–90 days | Same warm-soil requirements as watermelon; avoid disturbing roots when transplanting. |
| Corn | — | May 4 – May 18 | — | — | 60–100 days | Direct sow at last frost to 2 weeks after, once soil reaches 60F; does not transplant well. Succession sow every 2 weeks. |
| Green Bean | — | May 4 – May 18 | — | — | 50–65 days | Direct sow at last frost to 2 weeks after, once soil has warmed; frost-tender, do not rush. |
| Pea | — | Mar 23 – Apr 6 | — | — | 55–70 days | Cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Lettuce | — | Apr 6 – Apr 20 | — | Aug 13 – Aug 27 | 45–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. Also transplantable from indoor starts. |
| Spinach | — | Mar 23 – Apr 6 | — | Aug 13 – Aug 27 | 40–50 days | Very cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked. |
| Kale | — | Apr 6 – Apr 20 | — | Jul 30 – Aug 13 | 50–65 days | Cold-hardy; direct sow 2-4 weeks before last frost or start indoors for earlier transplants. |
| Arugula | — | Apr 6 – Apr 20 | — | Aug 27 – Sep 3 | 30–40 days | Fast-growing, cold-tolerant green; direct sow 2-4 weeks before last frost, succession sow every 2-3 weeks. |
| Swiss Chard | — | Apr 13 – Apr 27 | — | — | 50–60 days | Fairly cold-hardy; direct sow 1-3 weeks before last frost. Tolerates light frost in fall too. |
| Broccoli | Mar 16 – Mar 30 | — | Apr 13 – Apr 20 | Aug 6 – Aug 13 | 55–80 days | Start indoors 5-7 weeks before last frost; transplant out 2-3 weeks before last frost (hardens off to light frost). |
| Cauliflower | Mar 16 – Mar 30 | — | Apr 20 – Apr 27 | Jul 30 – Aug 6 | 55–85 days | Fussier than broccoli about temperature swings; start indoors 5-7 weeks before last frost, transplant 1-2 weeks before last frost. |
| Cabbage | Mar 16 – Mar 30 | — | Apr 6 – Apr 20 | Jul 30 – Aug 13 | 60–100 days | Cold-hardy; start indoors 5-7 weeks before last frost, transplant 2-4 weeks before last frost. |
| Brussels Sprouts | Mar 16 – Mar 30 | — | Apr 13 – Apr 27 | — | 90–110 days | Long-season crop best timed to mature after a light fall frost for sweetest flavor; start indoors 5-7 weeks before last frost. |
| Carrot | — | Apr 6 – Apr 20 | — | Jul 16 – Jul 30 | 60–80 days | Direct sow only (does not transplant); sow 2-4 weeks before last frost, as soon as soil can be worked. |
| Beet | — | Apr 6 – Apr 20 | — | Jul 30 – Aug 13 | 50–65 days | Direct sow 2-4 weeks before last frost; tolerates light frost. |
| Radish | — | Mar 30 – Apr 13 | — | Aug 27 – Sep 10 | 22–30 days | Very fast and cold-hardy; direct sow 3-5 weeks before last frost, as soon as soil can be worked. |
| Turnip | — | Apr 6 – Apr 20 | — | Jul 30 – Aug 13 | 40–60 days | Cold-hardy; direct sow 2-4 weeks before last frost. |
| Onion | Feb 23 – Mar 9 | — | Apr 6 – Apr 20 | — | 90–120 days | Start seeds indoors 8-10 weeks before last frost (or use sets/transplants); set out 2-4 weeks before last frost, very cold-tolerant as seedlings. |
| Garlic | — | — | — | Sep 10 – Sep 24 | 240–270 days | Fall-planted crop only; not planted in spring in most climates. |
| Potato | — | Apr 6 – Apr 20 | — | — | 70–120 days | Plant seed potatoes 2-4 weeks before last frost, as soon as soil can be worked and is above 45F; light frost on emerging foliage is usually tolerated. |
| Sweet Potato | — | — | May 18 – Jun 1 | — | 90–120 days | Set out slips 2-4 weeks after last frost once soil is thoroughly warm (65F+); very frost/cold sensitive. |
| Asparagus | — | — | Apr 6 – Apr 20 | — | 730–1095 days | Perennial; plant crowns 2-4 weeks before last frost as soon as soil can be worked. Takes 2-3 years to full production. |
| Crop | Start indoors | Direct sow | Transplant | Fall planting | Maturity | Notes |
|---|---|---|---|---|---|---|
| Basil | Mar 23 – Mar 30 | — | May 11 – May 18 | — | 50–70 days | Very frost/cold sensitive; start indoors 5-6 weeks before last frost, transplant only after all danger of frost (1-2 weeks after) and nights stay warm. |
| Cilantro | — | Apr 13 – Apr 27 | — | Aug 13 – Aug 27 | 45–70 days | Cool-season, bolts in heat; direct sow 1-3 weeks before last frost, succession sow through spring. |
| Parsley | Mar 9 – Mar 23 | — | Apr 20 – Apr 27 | — | 70–90 days | Slow to germinate; start indoors 6-8 weeks before last frost, transplant 1-2 weeks before last frost (biennial, cold-tolerant). |
| Dill | — | Apr 13 – Apr 27 | — | — | 40–60 days | Taprooted, does not transplant well; direct sow 1-3 weeks before last frost, succession sow through summer. |
| Oregano | Mar 9 – Mar 23 | — | May 4 – May 11 | — | 80–90 days | Perennial herb; start indoors 6-8 weeks before last frost, transplant around/just after last frost date. |
| Thyme | Mar 9 – Mar 23 | — | May 4 – May 11 | — | 85–95 days | Perennial herb, slow from seed; start indoors 6-8 weeks before last frost, transplant around/after last frost. |
| Crop | Start indoors | Direct sow | Transplant | Fall planting | Maturity | Notes |
|---|---|---|---|---|---|---|
| Sunflower | — | May 11 – May 25 | — | — | 70–100 days | Direct sow 1-3 weeks after last frost once soil has warmed; taprooted, resents transplanting. |
| Zinnia | Apr 6 – Apr 13 | May 11 – May 25 | May 11 – May 18 | — | 60–70 days | Frost-tender; direct sow 1-3 weeks after last frost, or start indoors 3-4 weeks early for earlier blooms. |
| Marigold | Mar 23 – Apr 6 | — | May 11 – May 18 | — | 45–60 days | Frost-tender; start indoors 4-6 weeks before last frost, transplant after all frost danger has passed. |
| Cosmos | Apr 6 – Apr 13 | May 11 – May 25 | May 11 – May 18 | — | 60–90 days | Easy from direct seed 1-3 weeks after last frost; can also start indoors 3-4 weeks early. |
| Nasturtium | — | May 11 – May 25 | — | — | 50–65 days | Frost-tender, resents root disturbance; direct sow 1-3 weeks after last frost once soil has warmed. |
| Dahlia | — | — | May 11 – May 25 | — | 90–120 days | Plant tubers 1-3 weeks after last frost once soil is warm (60F+); very frost-sensitive. |
Date ranges are estimates based on university extension guidelines and this city's NOAA frost normals — not a guarantee. Scroll to see all columns on narrow screens.
Frequently Asked Questions
When is the last frost in Commerce City, CO?
Based on 1991–2020 NOAA climate normals for the DENVER-STAPLETON, CO US station, the last spring frost in Commerce City typically falls around May 4. A cautious gardener might wait until May 16 (only a 10% chance of a later frost), while April 20 marks an earlier, higher-risk planting date.
When is the first frost in Commerce City, CO in fall?
The first fall frost in Commerce City typically arrives around October 8. To stay safe, assume frost could start as early as September 25; in milder years it can hold off until October 20.
How long is the growing season in Commerce City, CO?
Commerce City's average frost-free growing season is about 156 days, running from the typical last spring frost (May 4) to the typical first fall frost (October 8).
What USDA hardiness zone is Commerce City, CO in?
Commerce City, CO is in USDA plant hardiness zone 6a, per the USDA's 2023 Plant Hardiness Zone Map. A classic four-season climate with cold winters and a solid summer growing season.