Frost Dates for Rock Springs, WY 82901
Last spring frost May 28 · First fall frost September 19 · 114 frost-free days · USDA Zone 5b
ZIP 82901 has about 27,200 people.
Short season: 114 frost-free days. Spring frost risk spans May 12–June 13 (32 days). Fall frost risk spans September 5–September 30 (25 days).
Frost probability for 82901
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | June 13 | May 28 | May 12 |
| Fall (first frost) | September 5 | September 19 | September 30 |
Dates come from NOAA 1971–2000 freeze probabilities at ROCK SPRINGS AP (23.9 km away); the 50% date is the median year.
Which crops fit a 114-day season in Rock Springs
In Rock Springs (114 frost-free days, a short season), 31 of 56 planner crops fit outright, 15 get two plantings, 9 need an indoor start, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Apr 23 | Jun 11–Jun 18 | 72 | head-start: Even planted out Jun 11, the outdoor season is about 8 days short; choose an early variety or grow under cover. | — |
| Pepper | Apr 16 | Jun 11–Jun 18 | 72 | head-start: Even planted out Jun 11, the outdoor season is about 3 days short; choose an early variety or grow under cover. | — |
| Lettuce | Apr 2 | Apr 30–May 7 | 149 | two-plantings: Plant Apr 30 and again by Jul 29; both mature before Sep 26. | Jul 29 |
| Carrots | — | May 7–May 14 | 156 | fits: 70 days to maturity, 156 available after May 7. | Jul 18 |
| Cucumber | May 7 | Jun 11–Jun 18 | 86 | fits: 60 days to maturity, 86 available after Jun 11. | Jun 23 |
| Beans | — | Jun 4–Jun 18 | 100 | fits: 60 days to maturity, 100 available after Jun 4. | Jun 30 |
| Peas | — | Apr 2–Jun 11 | 177 | fits: 65 days to maturity, 177 available after Apr 2. | Jul 9 |
| Zucchini | May 14 | Jun 11–Jun 18 | 86 | fits: 55 days to maturity, 86 available after Jun 11. | Jun 28 |
| Onion | Mar 5 | Apr 30–May 14 | 149 | fits: 100 days to maturity, 149 available after Apr 30. | — |
| Spinach | — | Apr 2–May 21 | 191 | two-plantings: Plant Apr 2 and again by Aug 17; both mature before Oct 10. | Aug 17 |
| Kale | Mar 19 | Apr 30–May 14 | 163 | two-plantings: Plant Apr 30 and again by Aug 2; both mature before Oct 10. | Aug 2 |
| Broccoli | Apr 2 | Apr 30–May 14 | 149 | fits: 80 days to maturity, 149 available after Apr 30. | Jun 24 |
| Cabbage | Apr 2 | Apr 30–May 14 | 163 | fits: 70 days to maturity, 163 available after Apr 30. | Jul 18 |
| Radish | — | Apr 2–Jun 25 | 177 | two-plantings: Plant Apr 2 and again by Aug 18; both mature before Sep 26. | Aug 18 |
| Beets | — | Apr 2–Jun 25 | 177 | two-plantings: Plant Apr 2 and again by Jul 19; both mature before Sep 26. | Jul 19 |
| Potatoes | — | May 14–May 21 | 135 | fits: 90 days to maturity, 135 available after May 14. | — |
| Garlic | — | Sep 19 | 219 | overwinter: Plant Sep 19 to Oct 10; harvest the following summer. | Oct 10 |
| Strawberry | — | Apr 23–Jun 18 | 170 | perennial: A perennial: plant Apr 23; it fruits from the following year and keeps producing for several years. | — |
| Corn | Apr 30 | Jun 4–Jun 11 | 86 | fits: 75 days to maturity, 86 available after Jun 4. | — |
| Pumpkin | May 14 | Jun 11–Jun 11 | 79 | head-start: Even planted out Jun 11, the outdoor season is about 21 days short; choose an early variety or grow under cover. | — |
| Cauliflower | Apr 16 | May 21–Jun 4 | 128 | fits: 75 days to maturity, 128 available after May 21. | Jun 29 |
| Swiss Chard | Apr 2 | May 14–May 14 | 135 | two-plantings: Plant May 14 and again by Jul 19; both mature before Sep 26. | Jul 19 |
| Arugula | — | Apr 2–Jun 25 | 191 | two-plantings: Plant Apr 2 and again by Aug 17; both mature before Oct 10. | Aug 17 |
| Brussel Sprouts | Apr 2 | Apr 30–May 14 | 163 | fits: 100 days to maturity, 163 available after Apr 30. | Jun 18 |
| Butternut Squash | May 14 | Jun 11–Jun 18 | 79 | head-start: Even planted out Jun 11, the outdoor season is about 21 days short; choose an early variety or grow under cover. | — |
| Eggplant | Apr 9 | Jun 11–Jun 18 | 72 | fits: 70 days to maturity, 72 available after Jun 11. | — |
| Okra | Apr 30 | Jun 4–Jun 11 | 93 | fits: 55 days to maturity, 93 available after Jun 4. | Jun 28 |
| Basil | Apr 23 | Jun 18–Jun 18 | 79 | fits: 60 days to maturity, 79 available after Jun 18. | Jun 23 |
| Cilantro | — | Apr 30–May 21 | 149 | two-plantings: Plant Apr 30 and again by Jul 24; both mature before Sep 26. | Jul 24 |
| Parsley | Mar 19 | Jun 4–Jun 11 | 114 | fits: 70 days to maturity, 114 available after Jun 4. | Jul 4 |
| Celery | Mar 19 | Jun 4–Jun 18 | 114 | head-start: Even planted out Jun 4, the outdoor season is about 6 days short; choose an early variety or grow under cover. | — |
| Scallions | Mar 19 | Apr 30–May 14 | 163 | two-plantings: Plant Apr 30 and again by Jul 28; both mature before Oct 10. | Jul 28 |
| Turnip | — | Apr 30–May 14 | 163 | two-plantings: Plant Apr 30 and again by Aug 7; both mature before Oct 10. | Aug 7 |
| Kohlrabi | — | Apr 16–Apr 30 | 177 | two-plantings: Plant Apr 16 and again by Aug 2; both mature before Oct 10. | Aug 2 |
| Bok Choy | Apr 30 | May 21–May 28 | 128 | two-plantings: Plant May 21 and again by Jul 29; both mature before Sep 26. | Jul 29 |
| Collards | Mar 19 | Apr 30–May 14 | 163 | two-plantings: Plant Apr 30 and again by Jul 28; both mature before Oct 10. | Jul 28 |
| Cantaloupe | May 14 | Jun 11–Jun 18 | 72 | head-start: Even planted out Jun 11, the outdoor season is about 13 days short; choose an early variety or grow under cover. | — |
| Chives | Mar 5 | Jun 4–Jun 11 | 128 | fits: 90 days to maturity, 128 available after Jun 4. | — |
| Dill | — | Apr 2–Jun 25 | 177 | two-plantings: Plant Apr 2 and again by Jul 19; both mature before Sep 26. | Jul 19 |
| Oregano | Mar 19 | Jun 4–Jun 11 | 128 | fits: 80 days to maturity, 128 available after Jun 4. | — |
| Rosemary | Mar 5 | Jun 4–Jun 11 | 114 | fits: 80 days to maturity, 114 available after Jun 4. | — |
| Sage | Apr 2 | Jun 4–Jun 11 | 128 | fits: 75 days to maturity, 128 available after Jun 4. | — |
| Thyme | Mar 19 | Jun 4–Jun 11 | 128 | fits: 90 days to maturity, 128 available after Jun 4. | — |
| Calendula | Apr 16 | May 14–May 28 | 135 | two-plantings: Plant May 14 and again by Jul 24; both mature before Sep 26. | Jul 24 |
| Cosmos | Apr 30 | May 28–Jun 11 | 100 | fits: 60 days to maturity, 100 available after May 28. | Jun 23 |
| Lavender | Mar 5 | May 28–Jun 11 | 135 | fits: 90 days to maturity, 135 available after May 28. | — |
| Marigolds | Apr 16 | May 28–Jun 4 | 100 | fits: 50 days to maturity, 100 available after May 28. | Jul 3 |
| Melons | May 14 | Jun 11–Jun 18 | 72 | head-start: Even planted out Jun 11, the outdoor season is about 13 days short; choose an early variety or grow under cover. | — |
| Mint | — | May 28–Jun 11 | 135 | fits: 90 days to maturity, 135 available after May 28. | — |
| Nasturtiums | Apr 30 | May 28–Jun 4 | 100 | fits: 55 days to maturity, 100 available after May 28. | Jun 28 |
| Pole Beans | — | Jun 4–Jun 18 | 93 | fits: 65 days to maturity, 93 available after Jun 4. | Jun 18 |
| Spaghetti Squash | May 14 | Jun 11–Jun 18 | 79 | head-start: Even planted out Jun 11, the outdoor season is about 11 days short; choose an early variety or grow under cover. | — |
| Sunflowers | — | May 28–Jun 11 | 100 | fits: 70 days to maturity, 100 available after May 28. | Jun 13 |
| Tomatillos | Apr 2 | Jun 4–Jun 11 | 79 | fits: 75 days to maturity, 79 available after Jun 4. | — |
| Watermelon | May 14 | Jun 4–Jun 11 | 79 | head-start: Even planted out Jun 4, the outdoor season is about 1 days short; choose an early variety or grow under cover. | — |
| Yellow Squash | May 14 | Jun 11–Jun 18 | 86 | fits: 55 days to maturity, 86 available after Jun 11. | Jun 28 |
| Zinnias | Apr 30 | May 28–Jun 11 | 100 | fits: 60 days to maturity, 100 available after May 28. | Jun 23 |
Month by month in Rock Springs
| Month | What to do |
|---|---|
| January | Plan your garden layout and order seeds. Research varieties suited to your frost dates. |
| February | Start the slowest-growing crops indoors: onions, leeks, and celery (10–12 weeks before last frost). |
| March | Start indoors: Chives (Mar 5), Lavender (Mar 5), Onion (Mar 5), Rosemary (Mar 5), Celery (Mar 19), Collards (Mar 19), +5 more. |
| April | Start indoors: Broccoli (Apr 2), Brussel Sprouts (Apr 2), Cabbage (Apr 2), Lettuce (Apr 2), Sage (Apr 2), Swiss Chard (Apr 2), +14 more. Direct sow from: Arugula (Apr 2), Beets (Apr 2), Dill (Apr 2), Peas (Apr 2), Radish (Apr 2), Spinach (Apr 2), +3 more. Transplant from: Broccoli (Apr 30), Brussel Sprouts (Apr 30), Cabbage (Apr 30), Collards (Apr 30), Kale (Apr 30), Lettuce (Apr 30), +2 more. Plant: Strawberry (Apr 23). |
| May | Start indoors: Cucumber (May 7), Butternut Squash (May 14), Cantaloupe (May 14), Melons (May 14), Pumpkin (May 14), Spaghetti Squash (May 14), +3 more. Direct sow from: Carrots (May 7), Potatoes (May 14), Sunflowers (May 28). Transplant from: Calendula (May 14), Swiss Chard (May 14), Bok Choy (May 21), Cauliflower (May 21), Cosmos (May 28), Lavender (May 28), +4 more. Last frost around May 28. |
| June | Direct sow from: Beans (Jun 4), Pole Beans (Jun 4). Transplant from: Celery (Jun 4), Chives (Jun 4), Corn (Jun 4), Okra (Jun 4), Oregano (Jun 4), Parsley (Jun 4), +17 more. Last sowing dates: Sunflowers (Jun 13), Brussel Sprouts (Jun 18), Pole Beans (Jun 18), Basil (Jun 23), Cosmos (Jun 23), Cucumber (Jun 23), +8 more. |
| July | Last sowing dates: Marigolds (Jul 3), Parsley (Jul 4), Peas (Jul 9), Cabbage (Jul 18), Carrots (Jul 18), Beets (Jul 19), +8 more. |
| August | Last sowing dates: Kale (Aug 2), Kohlrabi (Aug 2), Turnip (Aug 7), Arugula (Aug 17), Spinach (Aug 17), Radish (Aug 18). |
| September | Direct sow from: Garlic (Sep 19). First frost around September 19. |
| October | Last sowing dates: Garlic (Oct 10). |
| November | Clean up spent plants. Add compost to beds. Rest, review, and plan next year's garden. |
| December | Clean up spent plants. Add compost to beds. Rest, review, and plan next year's garden. |
Frequently Asked Questions
What is the last frost date for Rock Springs, WY (ZIP 82901)?
The median last spring frost date for Rock Springs, WY (ZIP code 82901) is around May 28. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area. One year in ten frost ends before May 12; one in ten it runs past June 13.
What is the first fall frost date in Rock Springs, WY?
The median first fall frost date for Rock Springs, WY is around September 19. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses. The first frost arrives around September 5 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Rock Springs, WY?
The frost-free growing season in Rock Springs is about 114 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side. In Rock Springs (114 frost-free days, a short season), 31 of 56 planner crops fit outright, 15 get two plantings, 9 need an indoor start, 1 crop is perennial.
What USDA hardiness zone is Rock Springs, WY?
Rock Springs, WY is in USDA hardiness zone 5b (2023 USDA Plant Hardiness Zone Map). Zones come from the average coldest winter temperature, so they tell you which perennials survive the winter; the frost dates on this page tell you when to plant.
When should I start tomatoes indoors in Rock Springs, WY?
Start tomatoes indoors Apr 23 and plant out Jun 11 in Rock Springs. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Rock Springs?
Two: plant Apr 30 and again by Jul 29; both mature before Sep 26.
When do I plant garlic in Rock Springs?
Sep 19 to Oct 10; it overwinters and is ready the following summer.
Can I grow Celery in Rock Springs?
Yes, with help. Even planted out Jun 4, the outdoor season is about 6 days short; choose an early variety or grow under cover.
Which nearby ZIP has a longer season?
Vernal (ZIP 84078) has 126 frost-free days, 12 more than Rock Springs (ZIP 82901). See Vernal ZIP 84078 frost dates
Nearby and related
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- When to plant in WY
- When to plant Beans in WY
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- When to plant Broccoli in WY
- When to plant Carrots in WY
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