Gardening in Chicago-Naperville-Elgin, IL-IN
This metro spans USDA zones 5b to 6b, so there is no single zone for Chicago-Naperville-Elgin, IL-IN and anyone who gives you one is rounding. 59% of its ZIP codes are zone 6a; the rest are not.
Which zone you are in depends where you are
Chicago-Naperville-Elgin, IL-IN covers 3 hardiness zones. A guide that gives the metro one zone has picked whichever is largest and rounded everyone else into it — which is fine for the 59% in zone 6a and wrong for the other 41%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 6a | 220 | 59% | |
| 5b | 140 | 37% | |
| 6b | 14 | 4% |
Zones are published per ZIP code, so yours is exact even though the metro's is not. The hardiness tool will tell you which one you are in.
Your freeze dates
Those are the earliest and latest medians among the 38 stations serving this metro — not an average, and not one station standing in for the rest. Half of years freeze later than a station's own median.
The spread is the point. Even in a metro that is one hardiness zone throughout, its stations disagree about the last spring freeze. Hardiness zone and frost date measure different things — a zone is the average annual coldest night, a freeze date is when the season turns — and a place can be uniform in one and varied in the other. Use the tools below with your own ZIP rather than the ends of this range.
Your growing season
NOAA publishes a growing-season length for each station, and across the 38 stations serving Chicago-Naperville-Elgin, IL-IN it runs 162–208 days . That figure is published, not computed from the two freeze dates — subtracting one from the other gives the wrong answer wherever a season crosses New Year. Mean summer high (June–August) runs 79–87 °F , below the 90 °F point where cool-season crops reliably bolt.
When to start seeds in Chicago-Naperville-Elgin, IL-IN
Every spring job for 63 crop dates, counted from this metro's own last spring freeze. Each is a range across all 38 stations — the earliest and latest that job falls anywhere in the metro — because no one station speaks for the whole area.
| Crop | Job | When | Offset |
|---|---|---|---|
| Green Onions | Start indoors | February 13 – March 6 | 8 weeks before |
| Peppers | Start indoors | February 13 – March 6 | 8 weeks before |
| Broccoli | Start indoors | February 27 – March 20 | 6 weeks before |
| Cabbage | Start indoors | February 27 – March 20 | 6 weeks before |
| Collards | Start indoors | February 27 – March 20 | 6 weeks before |
| Kale | Start indoors | February 27 – March 20 | 6 weeks before |
| Leaf Lettuce | Start indoors | February 27 – March 20 | 6 weeks before |
| Peas | Direct sow | February 27 – March 20 | 6 weeks before |
| Spinach | Direct sow | February 27 – March 20 | 6 weeks before |
| Sweet Potato | Start indoors | February 27 – March 20 | 6 weeks before |
| Tomatoes | Start indoors | February 27 – March 20 | 6 weeks before |
| Bok Choy | Start indoors | March 6 – March 27 | 5 weeks before |
| Kohlrabi | Start indoors | March 6 – March 27 | 5 weeks before |
| Swiss Chard | Start indoors | March 6 – March 27 | 5 weeks before |
| Arugula | Direct sow | March 13 – April 3 | 4 weeks before |
| Baby Salad Greens | Direct sow | March 13 – April 3 | 4 weeks before |
| Beets | Direct sow | March 13 – April 3 | 4 weeks before |
| Green Onions | Direct sow | March 13 – April 3 | 4 weeks before |
| Mustard Greens | Direct sow | March 13 – April 3 | 4 weeks before |
| Okra | Start indoors | March 13 – April 3 | 4 weeks before |
| Radishes | Direct sow | March 13 – April 3 | 4 weeks before |
| Turnips | Direct sow | March 13 – April 3 | 4 weeks before |
| Cabbage | Set out | March 20 – April 10 | 3 weeks before |
| Carrots | Direct sow | March 20 – April 10 | 3 weeks before |
| Collards | Direct sow | March 20 – April 10 | 3 weeks before |
| Collards | Set out | March 20 – April 10 | 3 weeks before |
| Cucumbers | Start indoors | March 20 – April 10 | 3 weeks before |
| Green Onions | Set out | March 20 – April 10 | 3 weeks before |
| Kale | Direct sow | March 20 – April 10 | 3 weeks before |
| Kale | Set out | March 20 – April 10 | 3 weeks before |
| Kohlrabi | Direct sow | March 20 – April 10 | 3 weeks before |
| Kohlrabi | Set out | March 20 – April 10 | 3 weeks before |
| Leaf Lettuce | Direct sow | March 20 – April 10 | 3 weeks before |
| Pumpkins | Start indoors | March 20 – April 10 | 3 weeks before |
| Summer Squash | Start indoors | March 20 – April 10 | 3 weeks before |
| Winter Squash | Start indoors | March 20 – April 10 | 3 weeks before |
| Zucchini | Start indoors | March 20 – April 10 | 3 weeks before |
| Bok Choy | Direct sow | March 27 – April 17 | 2 weeks before |
| Bok Choy | Set out | March 27 – April 17 | 2 weeks before |
| Broccoli | Set out | March 27 – April 17 | 2 weeks before |
| Cilantro | Direct sow | March 27 – April 17 | 2 weeks before |
| Leaf Lettuce | Set out | March 27 – April 17 | 2 weeks before |
| Swiss Chard | Direct sow | March 27 – April 17 | 2 weeks before |
| Swiss Chard | Set out | March 27 – April 17 | 2 weeks before |
| Dill | Direct sow | April 3 – April 24 | 1 week before |
| Bush Beans | Direct sow | April 17 – May 8 | 1 week after |
| Cucumbers | Set out | April 17 – May 8 | 1 week after |
| Pumpkins | Direct sow | April 17 – May 8 | 1 week after |
| Pumpkins | Set out | April 17 – May 8 | 1 week after |
| Summer Squash | Direct sow | April 17 – May 8 | 1 week after |
| Summer Squash | Set out | April 17 – May 8 | 1 week after |
| Sweet Corn | Direct sow | April 17 – May 8 | 1 week after |
| Tomatoes | Set out | April 17 – May 8 | 1 week after |
| Winter Squash | Direct sow | April 17 – May 8 | 1 week after |
| Winter Squash | Set out | April 17 – May 8 | 1 week after |
| Zucchini | Direct sow | April 17 – May 8 | 1 week after |
| Zucchini | Set out | April 17 – May 8 | 1 week after |
| Cucumbers | Direct sow | April 24 – May 15 | 2 weeks after |
| Okra | Direct sow | April 24 – May 15 | 2 weeks after |
| Okra | Set out | April 24 – May 15 | 2 weeks after |
| Peppers | Set out | April 24 – May 15 | 2 weeks after |
| Southern Peas | Direct sow | April 24 – May 15 | 2 weeks after |
| Sweet Potato | Set out | April 24 – May 15 | 2 weeks after |
The week offsets are conventional extension guidance and vary by variety; the freeze dates they are counted from are measured. For a single date rather than a range, run when do I start my seeds? with your own ZIP code.
What survives the winter changes across Chicago-Naperville-Elgin, IL-IN
Of 74 perennial fruits, nuts, berries, vegetables and herbs, 51 come through the winter in zone 6a and only 48 in zone 5b. That is a different garden at each end of the same metro.
| Zone | ZIPs | Survive | Fail for being too warm |
|---|---|---|---|
| 5b | 140 | 48 of 74 | 0 |
| 6a | 220 | 51 of 74 | 0 |
| 6b | 14 | 51 of 74 | 0 |
The last column is the counterintuitive one, and it is why the totals do not simply rise as the winters get milder. Most temperate fruit needs a documented number of hours below about 45 °F to break dormancy and set a crop, so an apple fails in a winter that is too warm; currants and rhubarb cook in the summer heat that comes with it. See the full list with reasons.
The 38 stations behind these numbers
Every figure above comes from these, and each is named so you can check it. Distances vary by ZIP code, so the tools report yours rather than this page guessing.
| Station | NOAA ID | Last spring freeze | First fall freeze | Season |
|---|---|---|---|---|
| Antioch, IL | USC00110203 | April 23 | October 21 | 179 days |
| Aurora, IL | USC00110338 | April 19 | October 23 | 185 days |
| Barrington 3Sw, IL | USC00110442 | April 25 | October 19 | 177 days |
| Channahon Dresden Isl Dam, IL | USC00111420 | April 16 | October 26 | 191 days |
| Chicago Aurora Muni AP, IL | USW00004808 | April 28 | October 13 | 166 days |
| Chicago Botanic Garden, IL | USC00111497 | April 26 | October 21 | 176 days |
| Chicago Midway AP 3Sw, IL | USC00111577 | April 10 | November 1 | 203 days |
| Chicago Midway AP, IL | USW00014819 | April 11 | October 31 | 201 days |
| Chicago Northerly Is, IL | USC00111550 | April 10 | November 5 | 208 days |
| Chicago Ohare INTL AP, IL | USW00094846 | April 16 | October 28 | 193 days |
| Chicago Palwaukee AP, IL | USW00004838 | April 19 | October 26 | 190 days |
| Chicago Waukegan Rgnl AP, IL | USW00014880 | April 30 | October 21 | 173 days |
| Crystal Lake 4Nw, IL | USC00112048 | April 25 | October 22 | 179 days |
| De Kalb, IL | USC00112223 | April 24 | October 18 | 177 days |
| Dwight, IL | USC00112500 | April 27 | October 15 | 170 days |
| Elgin, IL | USC00112736 | April 26 | October 18 | 174 days |
| Indiana Dunes Nl, IN | USC00124244 | April 22 | October 27 | 188 days |
| Joliet Brandon Rd Dam, IL | USC00114530 | April 19 | October 25 | 188 days |
| Kentland, IN | USC00124527 | April 23 | October 14 | 175 days |
| Lake Villa 2Ne, IL | USC00114837 | April 24 | October 23 | 180 days |
| Lisle-Morton Arboretum, IL | USC00115097 | April 28 | October 16 | 169 days |
| Little Red School Hse, IL | USC00115110 | April 19 | October 22 | 183 days |
| Lowell, IN | USC00125174 | April 29 | October 16 | 171 days |
| Marengo, IL | USC00115326 | April 28 | October 12 | 166 days |
| Mc Henry -Wg Stratton L&D, IL | USC00115493 | May 1 | October 11 | 162 days |
| Morris 1 NW, IL | USC00115825 | April 20 | October 23 | 184 days |
| Mundelein 4 Wsw, IL | USC00115961 | April 29 | October 20 | 172 days |
| Park Forest, IL | USC00116616 | April 23 | October 20 | 179 days |
| Pell Lake, WI | USC00476420 | April 30 | October 13 | 164 days |
| Rensselaer, IN | USC00127298 | April 23 | October 18 | 177 days |
| Romeoville Wfo, IL | USC00117457 | April 20 | October 22 | 184 days |
| Shabbona 5 Nne, IL | USW00054811 | April 28 | October 10 | 163 days |
| Streamwood, IL | USC00118324 | April 30 | October 13 | 163 days |
| Valparaiso Porter Co Muni AP, IN | USW00004846 | April 20 | October 26 | 187 days |
| Valparaiso Wtr Wks, IN | USC00128999 | April 22 | October 25 | 185 days |
| Waukegan, IL | USC00119029 | April 30 | October 19 | 170 days |
| West Chicago Dupage AP, IL | USW00094892 | April 25 | October 19 | 174 days |
| Wheatfield, IN | USC00129511 | April 25 | October 17 | 173 days |
These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.
Work out your own dates
Each of these takes a ZIP code and answers for that ZIP alone, citing the station it used and how far away it is. There is a ZIP box in the header of every page.
- What survives my winter?
Runs on the hardiness zone, so it answers for all of Chicago-Naperville-Elgin, IL-IN at once — zone across 74 perennial fruits, berries, vegetables and herbs.
- When do I start my seeds?
Dates every spring job from your own last freeze — sow indoors, set out, direct sow.
- When do I sow the next round?
How often each crop is worth re-sowing, and when the next sowing is due.
- What can I still plant?
Counts the growing days left before your first fall freeze, crop by crop.
Where these numbers come from
The hardiness zone is the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. The freeze dates are NOAA's 1991–2020 Climate Normals, read from every station whose normals cover a ZIP code in this metro. Nothing here is estimated, and no station stands in for another.
This page names no single station on purpose. Picking one to represent a metro sounds reasonable and is not: the station serving the most ZIP codes is an artifact of where ZIP centroids happen to fall, and it selects a lock on the Monongahela for Pittsburgh and a far southern suburb for Chicago. A range across every station is true; a single cited date for a whole metro is not.