Frost Dates for Libby, MT 59923
Last spring frost June 9 · First fall frost September 11 · 94 frost-free days · USDA Zone 6a
ZIP 59923 has about 10,500 people.
Short season: 94 frost-free days. Spring frost risk spans May 15–July 4 (50 days). Fall frost risk spans August 22–September 29 (38 days).
Frost probability for 59923
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | July 4 | June 9 | May 15 |
| Fall (first frost) | August 22 | September 11 | September 29 |
Dates come from NOAA 1971–2000 freeze probabilities at TROUT CREEK RS (50.7 km away); the 50% date is the median year.
Which crops fit a 94-day season in Libby
In Libby (94 frost-free days, a short season), 28 of 56 planner crops fit outright, 14 get two plantings, 5 need an indoor start, 8 don't reliably mature, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | May 5 | Jun 23–Jun 30 | 52 | no-fit: Needs 80 days; Libby has 52 after Jun 23. | — |
| Pepper | Apr 28 | Jun 23–Jun 30 | 52 | no-fit: Needs 75 days; Libby has 52 after Jun 23. | — |
| Lettuce | Apr 14 | May 12–May 19 | 129 | two-plantings: Plant May 12 and again by Jul 21; both mature before Sep 18. | Jul 21 |
| Carrots | — | May 19–May 26 | 136 | fits: 70 days to maturity, 136 available after May 19. | Jul 10 |
| Cucumber | May 19 | Jun 23–Jun 30 | 66 | fits: 60 days to maturity, 66 available after Jun 23. | — |
| Beans | — | Jun 16–Jun 30 | 80 | fits: 60 days to maturity, 80 available after Jun 16. | Jun 22 |
| Peas | — | Apr 14–Jun 23 | 157 | fits: 65 days to maturity, 157 available after Apr 14. | Jul 1 |
| Zucchini | May 26 | Jun 23–Jun 30 | 66 | fits: 55 days to maturity, 66 available after Jun 23. | — |
| Onion | Mar 17 | May 12–May 26 | 129 | fits: 100 days to maturity, 129 available after May 12. | — |
| Spinach | — | Apr 14–Jun 2 | 171 | two-plantings: Plant Apr 14 and again by Aug 9; both mature before Oct 2. | Aug 9 |
| Kale | Mar 31 | May 12–May 26 | 143 | two-plantings: Plant May 12 and again by Jul 25; both mature before Oct 2. | Jul 25 |
| Broccoli | Apr 14 | May 12–May 26 | 129 | fits: 80 days to maturity, 129 available after May 12. | Jun 16 |
| Cabbage | Apr 14 | May 12–May 26 | 143 | fits: 70 days to maturity, 143 available after May 12. | Jul 10 |
| Radish | — | Apr 14–Jul 7 | 157 | two-plantings: Plant Apr 14 and again by Aug 10; both mature before Sep 18. | Aug 10 |
| Beets | — | Apr 14–Jul 7 | 157 | two-plantings: Plant Apr 14 and again by Jul 11; both mature before Sep 18. | Jul 11 |
| Potatoes | — | May 26–Jun 2 | 115 | fits: 90 days to maturity, 115 available after May 26. | — |
| Garlic | — | Sep 11 | 199 | overwinter: Plant Sep 11 to Oct 2; harvest the following summer. | Oct 2 |
| Strawberry | — | May 5–Jun 30 | 150 | perennial: A perennial: plant May 5; it fruits from the following year and keeps producing for several years. | — |
| Corn | May 12 | Jun 16–Jun 23 | 66 | head-start: Even planted out Jun 16, the outdoor season is about 9 days short; choose an early variety or grow under cover. | — |
| Pumpkin | May 26 | Jun 23–Jun 23 | 59 | no-fit: Needs 100 days; Libby has 59 after Jun 23. | — |
| Cauliflower | Apr 28 | Jun 2–Jun 16 | 108 | fits: 75 days to maturity, 108 available after Jun 2. | Jun 21 |
| Swiss Chard | Apr 14 | May 26–May 26 | 115 | fits: 55 days to maturity, 115 available after May 26. | Jul 11 |
| Arugula | — | Apr 14–Jul 7 | 171 | two-plantings: Plant Apr 14 and again by Aug 9; both mature before Oct 2. | Aug 9 |
| Brussel Sprouts | Apr 14 | May 12–May 26 | 143 | fits: 100 days to maturity, 143 available after May 12. | Jun 10 |
| Butternut Squash | May 26 | Jun 23–Jun 30 | 59 | no-fit: Needs 100 days; Libby has 59 after Jun 23. | — |
| Eggplant | Apr 21 | Jun 23–Jun 30 | 52 | head-start: Even planted out Jun 23, the outdoor season is about 18 days short; choose an early variety or grow under cover. | — |
| Okra | May 12 | Jun 16–Jun 23 | 73 | fits: 55 days to maturity, 73 available after Jun 16. | Jun 20 |
| Basil | May 5 | Jun 30–Jun 30 | 59 | head-start: Even planted out Jun 30, the outdoor season is about 1 days short; choose an early variety or grow under cover. | — |
| Cilantro | — | May 12–Jun 2 | 129 | two-plantings: Plant May 12 and again by Jul 16; both mature before Sep 18. | Jul 16 |
| Parsley | Mar 31 | Jun 16–Jun 23 | 94 | fits: 70 days to maturity, 94 available after Jun 16. | Jun 26 |
| Celery | Mar 31 | Jun 16–Jun 30 | 94 | no-fit: Needs 120 days; Libby has 94 after Jun 16. | — |
| Scallions | Mar 31 | May 12–May 26 | 143 | two-plantings: Plant May 12 and again by Jul 20; both mature before Oct 2. | Jul 20 |
| Turnip | — | May 12–May 26 | 143 | two-plantings: Plant May 12 and again by Jul 30; both mature before Oct 2. | Jul 30 |
| Kohlrabi | — | Apr 28–May 12 | 157 | two-plantings: Plant Apr 28 and again by Jul 25; both mature before Oct 2. | Jul 25 |
| Bok Choy | May 12 | Jun 2–Jun 9 | 108 | two-plantings: Plant Jun 2 and again by Jul 21; both mature before Sep 18. | Jul 21 |
| Collards | Mar 31 | May 12–May 26 | 143 | two-plantings: Plant May 12 and again by Jul 20; both mature before Oct 2. | Jul 20 |
| Cantaloupe | May 26 | Jun 23–Jun 30 | 52 | no-fit: Needs 85 days; Libby has 52 after Jun 23. | — |
| Chives | Mar 17 | Jun 16–Jun 23 | 108 | fits: 90 days to maturity, 108 available after Jun 16. | — |
| Dill | — | Apr 14–Jul 7 | 157 | two-plantings: Plant Apr 14 and again by Jul 11; both mature before Sep 18. | Jul 11 |
| Oregano | Mar 31 | Jun 16–Jun 23 | 108 | fits: 80 days to maturity, 108 available after Jun 16. | — |
| Rosemary | Mar 17 | Jun 16–Jun 23 | 94 | fits: 80 days to maturity, 94 available after Jun 16. | — |
| Sage | Apr 14 | Jun 16–Jun 23 | 108 | fits: 75 days to maturity, 108 available after Jun 16. | — |
| Thyme | Mar 31 | Jun 16–Jun 23 | 108 | fits: 90 days to maturity, 108 available after Jun 16. | — |
| Calendula | Apr 28 | May 26–Jun 9 | 115 | two-plantings: Plant May 26 and again by Jul 16; both mature before Sep 18. | Jul 16 |
| Cosmos | May 12 | Jun 9–Jun 23 | 80 | fits: 60 days to maturity, 80 available after Jun 9. | Jun 15 |
| Lavender | Mar 17 | Jun 9–Jun 23 | 115 | fits: 90 days to maturity, 115 available after Jun 9. | — |
| Marigolds | Apr 28 | Jun 9–Jun 16 | 80 | fits: 50 days to maturity, 80 available after Jun 9. | Jun 25 |
| Melons | May 26 | Jun 23–Jun 30 | 52 | no-fit: Needs 85 days; Libby has 52 after Jun 23. | — |
| Mint | — | Jun 9–Jun 23 | 115 | fits: 90 days to maturity, 115 available after Jun 9. | — |
| Nasturtiums | May 12 | Jun 9–Jun 16 | 80 | fits: 55 days to maturity, 80 available after Jun 9. | Jun 20 |
| Pole Beans | — | Jun 16–Jun 30 | 73 | fits: 65 days to maturity, 73 available after Jun 16. | — |
| Spaghetti Squash | May 26 | Jun 23–Jun 30 | 59 | no-fit: Needs 90 days; Libby has 59 after Jun 23. | — |
| Sunflowers | — | Jun 9–Jun 23 | 80 | fits: 70 days to maturity, 80 available after Jun 9. | — |
| Tomatillos | Apr 14 | Jun 16–Jun 23 | 59 | head-start: Even planted out Jun 16, the outdoor season is about 16 days short; choose an early variety or grow under cover. | — |
| Watermelon | May 26 | Jun 16–Jun 23 | 59 | head-start: Even planted out Jun 16, the outdoor season is about 21 days short; choose an early variety or grow under cover. | — |
| Yellow Squash | May 26 | Jun 23–Jun 30 | 66 | fits: 55 days to maturity, 66 available after Jun 23. | — |
| Zinnias | May 12 | Jun 9–Jun 23 | 80 | fits: 60 days to maturity, 80 available after Jun 9. | Jun 15 |
Month by month in Libby
| 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 17), Lavender (Mar 17), Onion (Mar 17), Rosemary (Mar 17), Celery (Mar 31), Collards (Mar 31), +5 more. |
| April | Start indoors: Broccoli (Apr 14), Brussel Sprouts (Apr 14), Cabbage (Apr 14), Lettuce (Apr 14), Sage (Apr 14), Swiss Chard (Apr 14), +6 more. Direct sow from: Arugula (Apr 14), Beets (Apr 14), Dill (Apr 14), Peas (Apr 14), Radish (Apr 14), Spinach (Apr 14), +1 more. |
| May | Start indoors: Basil (May 5), Tomato (May 5), Bok Choy (May 12), Corn (May 12), Cosmos (May 12), Nasturtiums (May 12), +11 more. Direct sow from: Cilantro (May 12), Turnip (May 12), Carrots (May 19), Potatoes (May 26). Transplant from: Broccoli (May 12), Brussel Sprouts (May 12), Cabbage (May 12), Collards (May 12), Kale (May 12), Lettuce (May 12), +4 more. Plant: Strawberry (May 5). |
| June | Direct sow from: Sunflowers (Jun 9), Beans (Jun 16), Pole Beans (Jun 16). Transplant from: Bok Choy (Jun 2), Cauliflower (Jun 2), Cosmos (Jun 9), Lavender (Jun 9), Marigolds (Jun 9), Mint (Jun 9), +25 more. Last frost around June 9. Last sowing dates: Brussel Sprouts (Jun 10), Cosmos (Jun 15), Zinnias (Jun 15), Broccoli (Jun 16), Nasturtiums (Jun 20), Okra (Jun 20), +4 more. |
| July | Last sowing dates: Peas (Jul 1), Cabbage (Jul 10), Carrots (Jul 10), Beets (Jul 11), Dill (Jul 11), Swiss Chard (Jul 11), +9 more. |
| August | Last sowing dates: Arugula (Aug 9), Spinach (Aug 9), Radish (Aug 10). |
| September | Direct sow from: Garlic (Sep 11). First frost around September 11. |
| October | Last sowing dates: Garlic (Oct 2). |
| 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 Libby, MT (ZIP 59923)?
The median last spring frost date for Libby, MT (ZIP code 59923) is around June 9. 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 15; one in ten it runs past July 4.
What is the first fall frost date in Libby, MT?
The median first fall frost date for Libby, MT is around September 11. 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 August 22 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Libby, MT?
The frost-free growing season in Libby is about 94 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 Libby (94 frost-free days, a short season), 28 of 56 planner crops fit outright, 14 get two plantings, 5 need an indoor start, 8 don't reliably mature, 1 crop is perennial.
What USDA hardiness zone is Libby, MT?
Libby, MT is in USDA hardiness zone 6a (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 Libby, MT?
Start tomatoes indoors May 5 and plant out Jun 23 in Libby. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Libby?
Two: plant May 12 and again by Jul 21; both mature before Sep 18.
When do I plant garlic in Libby?
Sep 11 to Oct 2; it overwinters and is ready the following summer.
Can I grow Celery in Libby?
Not reliably outdoors. Needs 120 days; Libby has 94 after Jun 16.
Which nearby ZIP has a longer season?
Kalispell (ZIP 59901) has 115 frost-free days, 21 more than Libby (ZIP 59923). See Kalispell ZIP 59901 frost dates
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