Frost Dates for Harrisburg, IL 62946
Last spring frost April 12 · First fall frost October 17 · 188 frost-free days · USDA Zone 7a
ZIP 62946 has about 11,300 people.
Long season: 188 frost-free days. Spring frost risk spans March 29–April 27 (29 days). Fall frost risk spans October 2–November 2 (31 days).
Frost probability for 62946
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | April 27 | April 12 | March 29 |
| Fall (first frost) | October 2 | October 17 | November 2 |
Dates come from NOAA 1971–2000 freeze probabilities at DIXON SPRINGS AGRIC CTR (31.8 km away); the 50% date is the median year.
Which crops fit a 188-day season in Harrisburg
In Harrisburg (188 frost-free days, a long season), 30 of 56 planner crops fit outright, 25 get two plantings, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Mar 8 | Apr 26–May 3 | 146 | fits: 80 days to maturity, 146 available after Apr 26. | Jun 17 |
| Pepper | Mar 1 | Apr 26–May 3 | 146 | fits: 75 days to maturity, 146 available after Apr 26. | Jun 22 |
| Lettuce | Feb 15 | Mar 15–Mar 22 | 223 | two-plantings: Plant Mar 15 and again by Aug 26; both mature before Oct 24. | Aug 26 |
| Carrots | — | Mar 22–Mar 29 | 230 | fits: 70 days to maturity, 230 available after Mar 22. | Aug 15 |
| Cucumber | Mar 22 | Apr 26–May 3 | 160 | two-plantings: Plant Apr 26 and again by Jul 21; both mature before Oct 3. | Jul 21 |
| Beans | — | Apr 19–May 3 | 174 | two-plantings: Plant Apr 19 and again by Jul 28; both mature before Oct 10. | Jul 28 |
| Peas | — | Feb 15–Apr 26 | 251 | fits: 65 days to maturity, 251 available after Feb 15. | Aug 6 |
| Zucchini | Mar 29 | Apr 26–May 3 | 160 | two-plantings: Plant Apr 26 and again by Jul 26; both mature before Oct 3. | Jul 26 |
| Onion | Jan 18 | Mar 15–Mar 29 | 223 | fits: 100 days to maturity, 223 available after Mar 15. | — |
| Spinach | — | Feb 15–Apr 5 | 265 | two-plantings: Plant Feb 15 and again by Sep 14; both mature before Nov 7. | Sep 14 |
| Kale | Feb 1 | Mar 15–Mar 29 | 237 | two-plantings: Plant Mar 15 and again by Aug 30; both mature before Nov 7. | Aug 30 |
| Broccoli | Feb 15 | Mar 15–Mar 29 | 223 | fits: 80 days to maturity, 223 available after Mar 15. | Jul 22 |
| Cabbage | Feb 15 | Mar 15–Mar 29 | 237 | fits: 70 days to maturity, 237 available after Mar 15. | Aug 15 |
| Radish | — | Feb 15–May 10 | 251 | two-plantings: Plant Feb 15 and again by Sep 15; both mature before Oct 24. | Sep 15 |
| Beets | — | Feb 15–May 10 | 251 | two-plantings: Plant Feb 15 and again by Aug 16; both mature before Oct 24. | Aug 16 |
| Potatoes | — | Mar 29–Apr 5 | 209 | fits: 90 days to maturity, 209 available after Mar 29. | — |
| Garlic | — | Oct 17 | 293 | overwinter: Plant Oct 17 to Nov 7; harvest the following summer. | Nov 7 |
| Strawberry | — | Mar 8–May 3 | 244 | perennial: A perennial: plant Mar 8; it fruits from the following year and keeps producing for several years. | — |
| Corn | Mar 15 | Apr 19–Apr 26 | 160 | fits: 75 days to maturity, 160 available after Apr 19. | Jun 29 |
| Pumpkin | Mar 29 | Apr 26–Apr 26 | 153 | fits: 100 days to maturity, 153 available after Apr 26. | Jun 4 |
| Cauliflower | Mar 1 | Apr 5–Apr 19 | 202 | fits: 75 days to maturity, 202 available after Apr 5. | Jul 27 |
| Swiss Chard | Feb 15 | Mar 29–Mar 29 | 209 | two-plantings: Plant Mar 29 and again by Aug 16; both mature before Oct 24. | Aug 16 |
| Arugula | — | Feb 15–May 10 | 265 | two-plantings: Plant Feb 15 and again by Sep 14; both mature before Nov 7. | Sep 14 |
| Brussel Sprouts | Feb 15 | Mar 15–Mar 29 | 237 | fits: 100 days to maturity, 237 available after Mar 15. | Jul 16 |
| Butternut Squash | Mar 29 | Apr 26–May 3 | 153 | fits: 100 days to maturity, 153 available after Apr 26. | Jun 4 |
| Eggplant | Feb 22 | Apr 26–May 3 | 146 | fits: 70 days to maturity, 146 available after Apr 26. | Jun 27 |
| Okra | Mar 15 | Apr 19–Apr 26 | 167 | two-plantings: Plant Apr 19 and again by Jul 26; both mature before Oct 3. | Jul 26 |
| Basil | Mar 8 | May 3–May 3 | 153 | two-plantings: Plant May 3 and again by Jul 21; both mature before Oct 3. | Jul 21 |
| Cilantro | — | Mar 15–Apr 5 | 223 | two-plantings: Plant Mar 15 and again by Aug 21; both mature before Oct 24. | Aug 21 |
| Parsley | Feb 1 | Apr 19–Apr 26 | 188 | fits: 70 days to maturity, 188 available after Apr 19. | Aug 1 |
| Celery | Feb 1 | Apr 19–May 3 | 188 | fits: 120 days to maturity, 188 available after Apr 19. | Jun 12 |
| Scallions | Feb 1 | Mar 15–Mar 29 | 237 | two-plantings: Plant Mar 15 and again by Aug 25; both mature before Nov 7. | Aug 25 |
| Turnip | — | Mar 15–Mar 29 | 237 | two-plantings: Plant Mar 15 and again by Sep 4; both mature before Nov 7. | Sep 4 |
| Kohlrabi | — | Mar 1–Mar 15 | 251 | two-plantings: Plant Mar 1 and again by Aug 30; both mature before Nov 7. | Aug 30 |
| Bok Choy | Mar 15 | Apr 5–Apr 12 | 202 | two-plantings: Plant Apr 5 and again by Aug 26; both mature before Oct 24. | Aug 26 |
| Collards | Feb 1 | Mar 15–Mar 29 | 237 | two-plantings: Plant Mar 15 and again by Aug 25; both mature before Nov 7. | Aug 25 |
| Cantaloupe | Mar 29 | Apr 26–May 3 | 146 | fits: 85 days to maturity, 146 available after Apr 26. | Jun 12 |
| Chives | Jan 18 | Apr 19–Apr 26 | 202 | fits: 90 days to maturity, 202 available after Apr 19. | — |
| Dill | — | Feb 15–May 10 | 251 | two-plantings: Plant Feb 15 and again by Aug 16; both mature before Oct 24. | Aug 16 |
| Oregano | Feb 1 | Apr 19–Apr 26 | 202 | fits: 80 days to maturity, 202 available after Apr 19. | — |
| Rosemary | Jan 18 | Apr 19–Apr 26 | 188 | fits: 80 days to maturity, 188 available after Apr 19. | — |
| Sage | Feb 15 | Apr 19–Apr 26 | 202 | fits: 75 days to maturity, 202 available after Apr 19. | — |
| Thyme | Feb 1 | Apr 19–Apr 26 | 202 | fits: 90 days to maturity, 202 available after Apr 19. | — |
| Calendula | Mar 1 | Mar 29–Apr 12 | 209 | two-plantings: Plant Mar 29 and again by Aug 21; both mature before Oct 24. | Aug 21 |
| Cosmos | Mar 15 | Apr 12–Apr 26 | 174 | two-plantings: Plant Apr 12 and again by Jul 21; both mature before Oct 3. | Jul 21 |
| Lavender | Jan 18 | Apr 12–Apr 26 | 209 | fits: 90 days to maturity, 209 available after Apr 12. | — |
| Marigolds | Mar 1 | Apr 12–Apr 19 | 174 | two-plantings: Plant Apr 12 and again by Jul 31; both mature before Oct 3. | Jul 31 |
| Melons | Mar 29 | Apr 26–May 3 | 146 | fits: 85 days to maturity, 146 available after Apr 26. | Jun 12 |
| Mint | — | Apr 12–Apr 26 | 209 | fits: 90 days to maturity, 209 available after Apr 12. | — |
| Nasturtiums | Mar 15 | Apr 12–Apr 19 | 174 | two-plantings: Plant Apr 12 and again by Jul 26; both mature before Oct 3. | Jul 26 |
| Pole Beans | — | Apr 19–May 3 | 167 | fits: 65 days to maturity, 167 available after Apr 19. | Jul 16 |
| Spaghetti Squash | Mar 29 | Apr 26–May 3 | 153 | fits: 90 days to maturity, 153 available after Apr 26. | Jun 14 |
| Sunflowers | — | Apr 12–Apr 26 | 174 | fits: 70 days to maturity, 174 available after Apr 12. | Jul 11 |
| Tomatillos | Feb 15 | Apr 19–Apr 26 | 153 | fits: 75 days to maturity, 153 available after Apr 19. | Jun 22 |
| Watermelon | Mar 29 | Apr 19–Apr 26 | 153 | fits: 80 days to maturity, 153 available after Apr 19. | Jun 17 |
| Yellow Squash | Mar 29 | Apr 26–May 3 | 160 | two-plantings: Plant Apr 26 and again by Jul 26; both mature before Oct 3. | Jul 26 |
| Zinnias | Mar 15 | Apr 12–Apr 26 | 174 | two-plantings: Plant Apr 12 and again by Jul 21; both mature before Oct 3. | Jul 21 |
Month by month in Harrisburg
| Month | What to do |
|---|---|
| January | Start indoors: Chives (Jan 18), Lavender (Jan 18), Onion (Jan 18), Rosemary (Jan 18). |
| February | Start indoors: Celery (Feb 1), Collards (Feb 1), Kale (Feb 1), Oregano (Feb 1), Parsley (Feb 1), Scallions (Feb 1), +9 more. Direct sow from: Arugula (Feb 15), Beets (Feb 15), Dill (Feb 15), Peas (Feb 15), Radish (Feb 15), Spinach (Feb 15). |
| March | Start indoors: Calendula (Mar 1), Cauliflower (Mar 1), Marigolds (Mar 1), Pepper (Mar 1), Basil (Mar 8), Tomato (Mar 8), +15 more. Direct sow from: Kohlrabi (Mar 1), Cilantro (Mar 15), Turnip (Mar 15), Carrots (Mar 22), Potatoes (Mar 29). Transplant from: Broccoli (Mar 15), Brussel Sprouts (Mar 15), Cabbage (Mar 15), Collards (Mar 15), Kale (Mar 15), Lettuce (Mar 15), +4 more. Plant: Strawberry (Mar 8). |
| April | Direct sow from: Sunflowers (Apr 12), Beans (Apr 19), Pole Beans (Apr 19). Transplant from: Bok Choy (Apr 5), Cauliflower (Apr 5), Cosmos (Apr 12), Lavender (Apr 12), Marigolds (Apr 12), Mint (Apr 12), +24 more. Last frost around April 12. |
| May | Transplant from: Basil (May 3). |
| June | Last sowing dates: Butternut Squash (Jun 4), Pumpkin (Jun 4), Cantaloupe (Jun 12), Celery (Jun 12), Melons (Jun 12), Spaghetti Squash (Jun 14), +6 more. |
| July | Last sowing dates: Sunflowers (Jul 11), Brussel Sprouts (Jul 16), Pole Beans (Jul 16), Basil (Jul 21), Cosmos (Jul 21), Cucumber (Jul 21), +9 more. |
| August | Last sowing dates: Parsley (Aug 1), Peas (Aug 6), Cabbage (Aug 15), Carrots (Aug 15), Beets (Aug 16), Dill (Aug 16), +9 more. |
| September | Last sowing dates: Turnip (Sep 4), Arugula (Sep 14), Spinach (Sep 14), Radish (Sep 15). |
| October | Direct sow from: Garlic (Oct 17). First frost around October 17. |
| November | Last sowing dates: Garlic (Nov 7). |
| 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 Harrisburg, IL (ZIP 62946)?
The median last spring frost date for Harrisburg, IL (ZIP code 62946) is around April 12. 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 March 29; one in ten it runs past April 27.
What is the first fall frost date in Harrisburg, IL?
The median first fall frost date for Harrisburg, IL is around October 17. 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 October 2 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Harrisburg, IL?
The frost-free growing season in Harrisburg is about 188 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 Harrisburg (188 frost-free days, a long season), 30 of 56 planner crops fit outright, 25 get two plantings, 1 crop is perennial.
What USDA hardiness zone is Harrisburg, IL?
Harrisburg, IL is in USDA hardiness zone 7a (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 Harrisburg, IL?
Start tomatoes indoors Mar 8 and plant out Apr 26 in Harrisburg. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Harrisburg?
Two: plant Mar 15 and again by Aug 26; both mature before Oct 24.
When do I plant garlic in Harrisburg?
Oct 17 to Nov 7; it overwinters and is ready the following summer.
Can I get two tomato crops in Harrisburg?
Yes: plant out Apr 26 for a summer crop, and set out a second round of transplants by Jun 17 for a fall crop.
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