Frost Dates for South Beloit, IL 61080

Last spring frost April 30 · First fall frost October 6 · 159 frost-free days · USDA Zone 5b

Frost probability for 61080

Frost10%50%90%
Spring (last frost)May 14April 30April 16
Fall (first frost)September 21October 6October 21

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (33.0 km away); the 50% date is the median year.

Month by month in South Beloit

MonthWhat to do
JanuaryPlan your garden layout and order seeds. Research varieties suited to your frost dates.
FebruaryStart peppers and eggplant indoors 8–10 weeks before your last frost (around April 30). Start tomatoes about two weeks later, 6–8 weeks before last frost.
MarchStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
AprilLast frost around April 30. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
MayFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
JuneSuccession plant lettuce and greens. Keep beds weeded and watered consistently.
JulyHarvest regularly to encourage production. Monitor for pests and disease.
AugustMidsummer: harvest beans, zucchini, cucumbers. Start brassica seeds indoors for fall.
SeptemberFirst fall frost approaching (around October 6). Transplant fall brassicas. Sow spinach, arugula, and radishes.
OctoberFirst frost around October 6. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.
NovemberHarvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year.
DecemberClean up spent plants. Add compost to beds. Rest, review, and plan next year's garden.

What grows in a 159-day season

Frequently Asked Questions

What is the last frost date for South Beloit, IL (ZIP 61080)?

The median last spring frost date for South Beloit, IL (ZIP code 61080) is around April 30. 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.

What is the first fall frost date in South Beloit, IL?

The median first fall frost date for South Beloit, IL is around October 6. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses.

How long is the growing season in South Beloit, IL?

The frost-free growing season in South Beloit is about 159 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.

What USDA hardiness zone is South Beloit, IL?

Based on frost date patterns, South Beloit falls approximately in 5b. USDA hardiness zones are determined by average annual minimum winter temperatures and guide both plant selection and planting timing for your location.

When should I start tomatoes indoors in South Beloit, IL?

Start tomato seeds indoors 6–8 weeks before your last frost date (around April 30). For South Beloit, that's roughly March 5 to March 19. Transplant outdoors 1–2 weeks after your last frost.

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