Centennial, Colorado planting calendar and frost dates
Centennial is in USDA hardiness zone 6a. The last spring frost typically comes around May 5 and the first fall frost around October 8, giving about 154 frost-free days a year.
- Hardiness zone
- Zone 6a
- Typical last frost
- May 5
- Typical first frost
- October 8
- Frost-free season
- 154 days
Frost dates in Centennial
Last spring frost
- April 24Risky: frost later than this in 9 years out of 10
- May 5Typical: a later frost in half of years
- May 17Safe: a later frost only 1 year in 10
First fall frost
- September 25Risky: frost earlier than this 1 year in 10
- October 8Typical: an earlier frost in half of years
- October 20Late: frost before this in 9 years out of 10
The growing season between the typical last and first frosts is about 154 days. Frost here means a low of 32°F at the weather station. A hard freeze (28°F), which damages most hardy crops too, typically ends around April 25 and returns around October 17.
NOAA U.S. Climate Normals 1991-2020 for Denver Centennial Airport, 1.6 miles ESE of the city center. Low-lying and rural spots often frost later in spring and earlier in fall than airports and city centers.
What to plant each month in Centennial
January
Start indoors: onions
February
Start indoors: broccoli, cabbages, cauliflower, collard greens, kale, leeks, onions, oregano, parsley, petunias, ranunculus, rosemary, snapdragons
March
Start indoors: black-eyed susans, broccoli, cabbages, cauliflower, celery, chives, cilantro, collard greens, eggplants, ginger, kale, leeks, lettuce, marigolds, nasturtiums, oregano, parsley, peppers, petunias, ranunculus, rosemary, sage, snapdragons, spinach, swiss chard
Plant or sow outdoors: black-eyed susans, blueberries, garlic, grapes, grass seed, hollyhocks, kale, onions, peas, poppies, raspberries, rhubarb, strawberries, turnips, wildflowers
April
Start indoors: basil, cantaloupes, celery, cilantro, cosmos, cucumbers, eggplants, marigolds, nasturtiums, okra, peppers, pumpkins, ranunculus, tomatoes, watermelons, winter squash, zucchini
Plant or sow outdoors: beets, black-eyed susans, blackberries, blueberries, broccoli, cabbages, carrots, cauliflower, chives, cilantro, collard greens, dahlias, dill, figs, garlic, gladioli, grapes, grass seed, hollyhocks, kale, leeks, lettuce, onions, parsley, peas, poppies, radishes, ranunculus, raspberries, rhubarb, roses, snapdragons, spinach, strawberries, swiss chard, turnips, wildflowers
May
Start indoors: cantaloupes, cosmos, cucumbers, okra, pumpkins, watermelons, winter squash, zinnias, zucchini
Plant or sow outdoors: asparagus, basil, beets, cantaloupes, carrots, chives, cilantro, cucumbers, dahlias, dill, eggplants, figs, garden mums, ginger, gladioli, grapes, green beans, green onions, kentucky bluegrass, lavenders, leeks, lettuce, lilies, marigolds, mints, nasturtiums, oregano, parsley, peppers, perennial ryegrass, petunias, potatoes, pumpkins, ranunculus, rosemary, roses, sage, snapdragons, spinach, sunflowers, sweet corn, sweet peas, swiss chard, tall fescue, thyme, tomatoes, watermelons, winter squash, zucchini
June
Start indoors: zinnias
Plant or sow outdoors: asparagus, basil, bermudagrass, cantaloupes, celery, centipedegrass, cosmos, cucumbers, eggplants, garden mums, green beans, green onions, okra, peanuts, peppers, pumpkins, st. augustinegrass, sweet potatoes, tomatoes, watermelons, winter squash, zinnias, zoysiagrass, zucchini
July
Plant or sow outdoors: bermudagrass, centipedegrass, green onions, okra, st. augustinegrass, zinnias, zoysiagrass
Plant for fall: bearded irises, beets, broccoli, brussels sprouts, cabbages, carrots, cauliflower, collard greens, lettuce, peas, radishes, snapdragons, spinach, swiss chard, turnips
August
Plant for fall: azaleas, bearded irises, beets, broccoli, cabbages, carrots, cauliflower, clematis, coneflowers, crocuses, daffodils, daylilies, grass seed, hostas, hydrangeas, kale, lettuce, lilies, ornamental alliums, peonies, radishes, roses, saffron, snapdragons, spinach, swiss chard, tulips, turnips
September
Plant for fall: cabbages, cauliflower, crocuses, daffodils, daylilies, grass seed, hostas, hyacinths, kale, lilies, ornamental alliums, peonies, radishes, saffron, spinach, tulips
October
Plant for fall: crocuses, daffodils, garlic, hyacinths, lilies, ornamental alliums, peonies, tulips
Frost dates and zones by ZIP code in Centennial
Centennial's 6 main ZIP codes take their frost dates from 2 different NOAA stations: the typical last frost ranges from May 4 in 80016 to May 5 in 80122. Every one of them is in zone 6a.
| ZIP code | Zone | Weather station | Typical last frost | Typical first frost |
|---|---|---|---|---|
| 80015 | 6a | Denver Centennial Airport, 1.6 mi ESE | May 5 | Oct 8 |
| 80016 | 6a | Denver-Stapleton, 6.3 mi ENE | May 4 | Oct 8 |
| 80111 | 6a | Denver Centennial Airport, 1.6 mi ESE | May 5 | Oct 8 |
| 80112 | 6a | Denver Centennial Airport, 1.6 mi ESE | May 5 | Oct 8 |
| 80121 | 6a | Denver Centennial Airport, 1.6 mi ESE | May 5 | Oct 8 |
| 80122 | 6a | Denver Centennial Airport, 1.6 mi ESE | May 5 | Oct 8 |
Planting dates for popular crops in Centennial
| Plant | Start indoors | Plant or sow outdoors | Fall planting |
|---|---|---|---|
| Tomatoes | Apr 2 to 16 | May 28 to Jun 11 | — |
| Strawberries | — | Mar 24 to Apr 7 | — |
| Lettuce | Mar 10 to 24 | Apr 28 to May 12 | Jul 9 to Aug 13 |
| Cilantro | Mar 24 to Apr 7 | May 5 to 12 | — |
| Basil | Apr 9 to 23 | May 28 to Jun 4 | — |
| Potatoes | — | May 1 to 8 | — |
| Garlic | — | Mar 24 to Apr 7 | Oct 8 to 22 |
| Onions | Jan 13 to Feb 24 | Apr 7 to 21 | — |
| Cucumbers | Apr 30 to May 14 | May 28 to Jun 11 | — |
| Pumpkins | Apr 30 to May 14 | May 28 to Jun 11 | — |
| Peppers | Mar 12 to Apr 9 | May 28 to Jun 11 | — |
| Carrots | — | Apr 14 to May 5 | Jul 16 to Aug 6 |
| Sweet Potatoes | — | Jun 10 to 17 | — |
| Watermelons | Apr 23 to May 7 | May 28 to Jun 11 | — |
| Sweet Corn | — | May 5 to 19 | — |
| Green Beans | — | May 28 to Jun 11 | — |
| Zucchini | Apr 30 to May 14 | May 28 to Jun 11 | — |
| Broccoli | Feb 17 to Mar 10 | Apr 7 to 21 | Jul 23 to Aug 20 |
| Peas | — | Mar 24 to Apr 7 | Jul 16 to 30 |
| Spinach | Mar 24 to 31 | Apr 28 to May 12 | Jul 30 to Sep 3 |
| Sunflowers | — | May 5 to 26 | — |
| Zinnias | May 30 to Jun 6 | Jun 27 to Jul 11 | — |
| Tulips | — | — | Aug 27 to Oct 22 |
| Daffodils | — | — | Aug 27 to Oct 8 |
| Grass Seed | — | Mar 24 to Apr 7 | Aug 27 to Sep 10 |
Nearby cities
- Parker, CO zone 5b, last frost May 9
- Aurora, CO zone 6a, last frost May 4
- Denver, CO zone 6a, last frost May 4
- Castle Rock, CO zone 5b, last frost May 16
- Lakewood, CO zone 6a, last frost May 5
- Commerce City, CO zone 6a, last frost May 4
Planting in ColoradoAbout zone 6aPrintable calendar for Centennial
Questions
When is the last frost in Centennial?
Around May 5 in a typical year, based on NOAA's 1991-2020 records for Denver Centennial Airport. There is still a 1 in 10 chance of frost after May 17.
What planting zone is Centennial in?
USDA hardiness zone 6a (2023 map). The zone tells you which perennials survive the winter; planting dates depend on frost dates instead.
When should I plant tomatoes in Centennial?
Start seeds indoors April 2 to 16 and set plants out May 28 to June 11.
When is the first frost in Centennial?
Around October 8 in a typical year, and before September 25 about 1 year in 10.