Frost Dates for Janesville, WI 53545
Janesville has 3 ZIP codes. The Janesville, WI frost page lists all of them with their dates.
Last spring frost May 2 · First fall frost October 3 · 154 frost-free days · USDA Zone 5b
ZIP 53545 has about 24,700 people, one of 3 ZIP codes in Janesville.
Moderate season: 154 frost-free days. Spring frost risk spans April 19–May 16 (27 days). Fall frost risk spans September 21–October 17 (26 days).
Frost probability for 53545
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | May 16 | May 2 | April 19 |
| Fall (first frost) | September 21 | October 3 | October 17 |
Dates come from NOAA 1971–2000 freeze probabilities at STOUGHTON WWTP (24.7 km away); the 50% date is the median year.
Which crops fit a 154-day season in Janesville
In Janesville (154 frost-free days, a moderate season), 32 of 56 planner crops fit outright, 23 get two plantings, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Mar 28 | May 16–May 23 | 112 | fits: 80 days to maturity, 112 available after May 16. | Jun 3 |
| Pepper | Mar 21 | May 16–May 23 | 112 | fits: 75 days to maturity, 112 available after May 16. | Jun 8 |
| Lettuce | Mar 7 | Apr 4–Apr 11 | 189 | two-plantings: Plant Apr 4 and again by Aug 12; both mature before Oct 10. | Aug 12 |
| Carrots | — | Apr 11–Apr 18 | 196 | fits: 70 days to maturity, 196 available after Apr 11. | Aug 1 |
| Cucumber | Apr 11 | May 16–May 23 | 126 | fits: 60 days to maturity, 126 available after May 16. | Jul 7 |
| Beans | — | May 9–May 23 | 140 | two-plantings: Plant May 9 and again by Jul 14; both mature before Sep 26. | Jul 14 |
| Peas | — | Mar 7–May 16 | 217 | fits: 65 days to maturity, 217 available after Mar 7. | Jul 23 |
| Zucchini | Apr 18 | May 16–May 23 | 126 | two-plantings: Plant May 16 and again by Jul 12; both mature before Sep 19. | Jul 12 |
| Onion | Feb 7 | Apr 4–Apr 18 | 189 | fits: 100 days to maturity, 189 available after Apr 4. | — |
| Spinach | — | Mar 7–Apr 25 | 231 | two-plantings: Plant Mar 7 and again by Aug 31; both mature before Oct 24. | Aug 31 |
| Kale | Feb 21 | Apr 4–Apr 18 | 203 | two-plantings: Plant Apr 4 and again by Aug 16; both mature before Oct 24. | Aug 16 |
| Broccoli | Mar 7 | Apr 4–Apr 18 | 189 | fits: 80 days to maturity, 189 available after Apr 4. | Jul 8 |
| Cabbage | Mar 7 | Apr 4–Apr 18 | 203 | fits: 70 days to maturity, 203 available after Apr 4. | Aug 1 |
| Radish | — | Mar 7–May 30 | 217 | two-plantings: Plant Mar 7 and again by Sep 1; both mature before Oct 10. | Sep 1 |
| Beets | — | Mar 7–May 30 | 217 | two-plantings: Plant Mar 7 and again by Aug 2; both mature before Oct 10. | Aug 2 |
| Potatoes | — | Apr 18–Apr 25 | 175 | fits: 90 days to maturity, 175 available after Apr 18. | — |
| Garlic | — | Oct 3 | 259 | overwinter: Plant Oct 3 to Oct 24; harvest the following summer. | Oct 24 |
| Strawberry | — | Mar 28–May 23 | 210 | perennial: A perennial: plant Mar 28; it fruits from the following year and keeps producing for several years. | — |
| Corn | Apr 4 | May 9–May 16 | 126 | fits: 75 days to maturity, 126 available after May 9. | Jun 15 |
| Pumpkin | Apr 18 | May 16–May 16 | 119 | fits: 100 days to maturity, 119 available after May 16. | May 21 |
| Cauliflower | Mar 21 | Apr 25–May 9 | 168 | fits: 75 days to maturity, 168 available after Apr 25. | Jul 13 |
| Swiss Chard | Mar 7 | Apr 18–Apr 18 | 175 | two-plantings: Plant Apr 18 and again by Aug 2; both mature before Oct 10. | Aug 2 |
| Arugula | — | Mar 7–May 30 | 231 | two-plantings: Plant Mar 7 and again by Aug 31; both mature before Oct 24. | Aug 31 |
| Brussel Sprouts | Mar 7 | Apr 4–Apr 18 | 203 | fits: 100 days to maturity, 203 available after Apr 4. | Jul 2 |
| Butternut Squash | Apr 18 | May 16–May 23 | 119 | fits: 100 days to maturity, 119 available after May 16. | May 21 |
| Eggplant | Mar 14 | May 16–May 23 | 112 | fits: 70 days to maturity, 112 available after May 16. | Jun 13 |
| Okra | Apr 4 | May 9–May 16 | 133 | two-plantings: Plant May 9 and again by Jul 12; both mature before Sep 19. | Jul 12 |
| Basil | Mar 28 | May 23–May 23 | 119 | fits: 60 days to maturity, 119 available after May 23. | Jul 7 |
| Cilantro | — | Apr 4–Apr 25 | 189 | two-plantings: Plant Apr 4 and again by Aug 7; both mature before Oct 10. | Aug 7 |
| Parsley | Feb 21 | May 9–May 16 | 154 | fits: 70 days to maturity, 154 available after May 9. | Jul 18 |
| Celery | Feb 21 | May 9–May 23 | 154 | fits: 120 days to maturity, 154 available after May 9. | May 29 |
| Scallions | Feb 21 | Apr 4–Apr 18 | 203 | two-plantings: Plant Apr 4 and again by Aug 11; both mature before Oct 24. | Aug 11 |
| Turnip | — | Apr 4–Apr 18 | 203 | two-plantings: Plant Apr 4 and again by Aug 21; both mature before Oct 24. | Aug 21 |
| Kohlrabi | — | Mar 21–Apr 4 | 217 | two-plantings: Plant Mar 21 and again by Aug 16; both mature before Oct 24. | Aug 16 |
| Bok Choy | Apr 4 | Apr 25–May 2 | 168 | two-plantings: Plant Apr 25 and again by Aug 12; both mature before Oct 10. | Aug 12 |
| Collards | Feb 21 | Apr 4–Apr 18 | 203 | two-plantings: Plant Apr 4 and again by Aug 11; both mature before Oct 24. | Aug 11 |
| Cantaloupe | Apr 18 | May 16–May 23 | 112 | fits: 85 days to maturity, 112 available after May 16. | May 29 |
| Chives | Feb 7 | May 9–May 16 | 168 | fits: 90 days to maturity, 168 available after May 9. | — |
| Dill | — | Mar 7–May 30 | 217 | two-plantings: Plant Mar 7 and again by Aug 2; both mature before Oct 10. | Aug 2 |
| Oregano | Feb 21 | May 9–May 16 | 168 | fits: 80 days to maturity, 168 available after May 9. | — |
| Rosemary | Feb 7 | May 9–May 16 | 154 | fits: 80 days to maturity, 154 available after May 9. | — |
| Sage | Mar 7 | May 9–May 16 | 168 | fits: 75 days to maturity, 168 available after May 9. | — |
| Thyme | Feb 21 | May 9–May 16 | 168 | fits: 90 days to maturity, 168 available after May 9. | — |
| Calendula | Mar 21 | Apr 18–May 2 | 175 | two-plantings: Plant Apr 18 and again by Aug 7; both mature before Oct 10. | Aug 7 |
| Cosmos | Apr 4 | May 2–May 16 | 140 | two-plantings: Plant May 2 and again by Jul 7; both mature before Sep 19. | Jul 7 |
| Lavender | Feb 7 | May 2–May 16 | 175 | fits: 90 days to maturity, 175 available after May 2. | — |
| Marigolds | Mar 21 | May 2–May 9 | 140 | two-plantings: Plant May 2 and again by Jul 17; both mature before Sep 19. | Jul 17 |
| Melons | Apr 18 | May 16–May 23 | 112 | fits: 85 days to maturity, 112 available after May 16. | May 29 |
| Mint | — | May 2–May 16 | 175 | fits: 90 days to maturity, 175 available after May 2. | — |
| Nasturtiums | Apr 4 | May 2–May 9 | 140 | two-plantings: Plant May 2 and again by Jul 12; both mature before Sep 19. | Jul 12 |
| Pole Beans | — | May 9–May 23 | 133 | fits: 65 days to maturity, 133 available after May 9. | Jul 2 |
| Spaghetti Squash | Apr 18 | May 16–May 23 | 119 | fits: 90 days to maturity, 119 available after May 16. | May 31 |
| Sunflowers | — | May 2–May 16 | 140 | fits: 70 days to maturity, 140 available after May 2. | Jun 27 |
| Tomatillos | Mar 7 | May 9–May 16 | 119 | fits: 75 days to maturity, 119 available after May 9. | Jun 8 |
| Watermelon | Apr 18 | May 9–May 16 | 119 | fits: 80 days to maturity, 119 available after May 9. | Jun 3 |
| Yellow Squash | Apr 18 | May 16–May 23 | 126 | two-plantings: Plant May 16 and again by Jul 12; both mature before Sep 19. | Jul 12 |
| Zinnias | Apr 4 | May 2–May 16 | 140 | two-plantings: Plant May 2 and again by Jul 7; both mature before Sep 19. | Jul 7 |
Month by month in Janesville
| Month | What to do |
|---|---|
| January | Plan your garden layout and order seeds. Research varieties suited to your frost dates. |
| February | Start indoors: Chives (Feb 7), Lavender (Feb 7), Onion (Feb 7), Rosemary (Feb 7), Celery (Feb 21), Collards (Feb 21), +5 more. |
| March | Start indoors: Broccoli (Mar 7), Brussel Sprouts (Mar 7), Cabbage (Mar 7), Lettuce (Mar 7), Sage (Mar 7), Swiss Chard (Mar 7), +8 more. Direct sow from: Arugula (Mar 7), Beets (Mar 7), Dill (Mar 7), Peas (Mar 7), Radish (Mar 7), Spinach (Mar 7), +1 more. Plant: Strawberry (Mar 28). |
| April | Start indoors: Bok Choy (Apr 4), Corn (Apr 4), Cosmos (Apr 4), Nasturtiums (Apr 4), Okra (Apr 4), Zinnias (Apr 4), +9 more. Direct sow from: Cilantro (Apr 4), Turnip (Apr 4), Carrots (Apr 11), Potatoes (Apr 18). Transplant from: Broccoli (Apr 4), Brussel Sprouts (Apr 4), Cabbage (Apr 4), Collards (Apr 4), Kale (Apr 4), Lettuce (Apr 4), +6 more. |
| May | Direct sow from: Sunflowers (May 2), Beans (May 9), Pole Beans (May 9). Transplant from: Cosmos (May 2), Lavender (May 2), Marigolds (May 2), Mint (May 2), Nasturtiums (May 2), Zinnias (May 2), +23 more. Last frost around May 2. Last sowing dates: Butternut Squash (May 21), Pumpkin (May 21), Cantaloupe (May 29), Celery (May 29), Melons (May 29), Spaghetti Squash (May 31). |
| June | Last sowing dates: Tomato (Jun 3), Watermelon (Jun 3), Pepper (Jun 8), Tomatillos (Jun 8), Eggplant (Jun 13), Corn (Jun 15), +1 more. |
| July | Last sowing dates: Brussel Sprouts (Jul 2), Pole Beans (Jul 2), Basil (Jul 7), Cosmos (Jul 7), Cucumber (Jul 7), Zinnias (Jul 7), +10 more. |
| August | Last sowing dates: Cabbage (Aug 1), Carrots (Aug 1), Beets (Aug 2), Dill (Aug 2), Swiss Chard (Aug 2), Calendula (Aug 7), +10 more. |
| September | Last sowing dates: Radish (Sep 1). |
| October | Direct sow from: Garlic (Oct 3). First frost around October 3. Last sowing dates: Garlic (Oct 24). |
| November | Harvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year. |
| 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 Janesville, WI (ZIP 53545)?
The median last spring frost date for Janesville, WI (ZIP code 53545) is around May 2. 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 April 19; one in ten it runs past May 16.
What is the first fall frost date in Janesville, WI?
The median first fall frost date for Janesville, WI is around October 3. 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 21 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Janesville, WI?
The frost-free growing season in Janesville is about 154 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 Janesville (154 frost-free days, a moderate season), 32 of 56 planner crops fit outright, 23 get two plantings, 1 crop is perennial.
What USDA hardiness zone is Janesville, WI?
Janesville, WI 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 Janesville, WI?
Start tomatoes indoors Mar 28 and plant out May 16 in Janesville. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Janesville?
Two: plant Apr 4 and again by Aug 12; both mature before Oct 10.
When do I plant garlic in Janesville?
Oct 3 to Oct 24; it overwinters and is ready the following summer.
Nearby and related
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