What Grows in Glen Ellyn, Illinois

The last hard freeze (28°F) in Glen Ellyn typically lands around Apr 10, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about May 1.

The first hard freeze (28°F) in Glen Ellyn typically arrives around Oct 28, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 14, so the watching starts about Sep 28 — about 201 days after the spring freeze cleared.

Measured between 28°F hard freezes, Glen Ellyn sees about 201 frost-free days — roughly Apr 10 through Oct 28, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 1 to Oct 14, about 166 days.

The federal record around Glen Ellyn runs heavier than most — 3,795 documented sites, mostly Underground Storage Tanks entries (1,759), the nearest PFAS record about 0.1 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.

From about Sep 28 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Oct 28 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Oct 28. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.