Place guide
Planting zones in Denver-Aurora-Centennial, CO
This metro spans USDA zones 4a to 6a, so there is no single zone for Denver-Aurora-Centennial, CO and anyone who gives you one is rounding. 61% of its ZIP codes are zone 6a; the rest are not.
Your ZIP code
Get the exact answer for your address
Everything above describes Denver-Aurora-Centennial, CO as a whole. Hardiness zones and freeze dates are published per ZIP code, so yours is exact — enter it and this page will tell you your zone, which NOAA station it comes from and how far away that station is.
The growing season in Denver-Aurora-Centennial, CO is closing
Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives September 2 – October 14 across the 33 NOAA stations serving this metro area .
Your next season already has a date
The first job of it is 🧅 Green Onions, start indoors, around March 5 – April 26 — counted back from a last spring freeze of April 30 – June 21 here.
These are ranges across the whole metro area. The ZIP lookup above gives the dates from your own nearest station instead.
All 33 stations agreeAt least one station
Every one of the 33 NOAA stations serving this metro area counts June 21 – September 2 as growing season (73 days). Widening to any single station gives April 30 – October 14 (167 days).
That is a 94-day difference inside one metro area — which is why this page gives ranges rather than a single planting date. The ZIP lookup above resolves it to one station.
Which zone you are in depends where you are
Denver-Aurora-Centennial, CO covers 4 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 61% in zone 6a and wrong for the other 39%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 6a | 81 | 61% | |
| 5b | 45 | 34% | |
| 5a | 6 | 5% | |
| 4a | 1 | 1% |
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 33 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 33 stations serving Denver-Aurora-Centennial, CO it runs 71–165 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 65–89 °F , below the 90 °F point where cool-season crops reliably bolt. Summer rain over the same months runs 4.5–9.6" across those 30 stations, against the rough inch a week — about 13 inches over the same 92 days — that a vegetable garden is usually reckoned to want. The middle station covers about 47% of it, so expect to make up the rest. The inches are NOAA's published normals; the inch a week is a rule of thumb, and it takes no account of a 83 °F summer afternoon drying the soil faster than a cool one.
When to start seeds in Denver-Aurora-Centennial, CO
Every spring job for 63 crop dates, counted from this metro's own last spring freeze. Each is a range across all 33 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 | March 5 – April 26 | 8 weeks before |
| Peppers | Start indoors | March 5 – April 26 | 8 weeks before |
| Broccoli | Start indoors | March 19 – May 10 | 6 weeks before |
| Cabbage | Start indoors | March 19 – May 10 | 6 weeks before |
| Collards | Start indoors | March 19 – May 10 | 6 weeks before |
| Kale | Start indoors | March 19 – May 10 | 6 weeks before |
| Leaf Lettuce | Start indoors | March 19 – May 10 | 6 weeks before |
| Peas | Direct sow | March 19 – May 10 | 6 weeks before |
| Spinach | Direct sow | March 19 – May 10 | 6 weeks before |
| Sweet Potato | Start indoors | March 19 – May 10 | 6 weeks before |
| Tomatoes | Start indoors | March 19 – May 10 | 6 weeks before |
| Bok Choy | Start indoors | March 26 – May 17 | 5 weeks before |
| Kohlrabi | Start indoors | March 26 – May 17 | 5 weeks before |
| Swiss Chard | Start indoors | March 26 – May 17 | 5 weeks before |
| Arugula | Direct sow | April 2 – May 24 | 4 weeks before |
| Baby Salad Greens | Direct sow | April 2 – May 24 | 4 weeks before |
| Beets | Direct sow | April 2 – May 24 | 4 weeks before |
| Green Onions | Direct sow | April 2 – May 24 | 4 weeks before |
| Mustard Greens | Direct sow | April 2 – May 24 | 4 weeks before |
| Okra | Start indoors | April 2 – May 24 | 4 weeks before |
| Radishes | Direct sow | April 2 – May 24 | 4 weeks before |
| Turnips | Direct sow | April 2 – May 24 | 4 weeks before |
| Cabbage | Set out | April 9 – May 31 | 3 weeks before |
| Carrots | Direct sow | April 9 – May 31 | 3 weeks before |
| Collards | Direct sow | April 9 – May 31 | 3 weeks before |
| Collards | Set out | April 9 – May 31 | 3 weeks before |
| Cucumbers | Start indoors | April 9 – May 31 | 3 weeks before |
| Green Onions | Set out | April 9 – May 31 | 3 weeks before |
| Kale | Direct sow | April 9 – May 31 | 3 weeks before |
| Kale | Set out | April 9 – May 31 | 3 weeks before |
| Kohlrabi | Direct sow | April 9 – May 31 | 3 weeks before |
| Kohlrabi | Set out | April 9 – May 31 | 3 weeks before |
| Leaf Lettuce | Direct sow | April 9 – May 31 | 3 weeks before |
| Pumpkins | Start indoors | April 9 – May 31 | 3 weeks before |
| Summer Squash | Start indoors | April 9 – May 31 | 3 weeks before |
| Winter Squash | Start indoors | April 9 – May 31 | 3 weeks before |
| Zucchini | Start indoors | April 9 – May 31 | 3 weeks before |
| Bok Choy | Direct sow | April 16 – June 7 | 2 weeks before |
| Bok Choy | Set out | April 16 – June 7 | 2 weeks before |
| Broccoli | Set out | April 16 – June 7 | 2 weeks before |
| Cilantro | Direct sow | April 16 – June 7 | 2 weeks before |
| Leaf Lettuce | Set out | April 16 – June 7 | 2 weeks before |
| Swiss Chard | Direct sow | April 16 – June 7 | 2 weeks before |
| Swiss Chard | Set out | April 16 – June 7 | 2 weeks before |
| Dill | Direct sow | April 23 – June 14 | 1 week before |
| Bush Beans | Direct sow | May 7 – June 28 | 1 week after |
| Cucumbers | Set out | May 7 – June 28 | 1 week after |
| Pumpkins | Direct sow | May 7 – June 28 | 1 week after |
| Pumpkins | Set out | May 7 – June 28 | 1 week after |
| Summer Squash | Direct sow | May 7 – June 28 | 1 week after |
| Summer Squash | Set out | May 7 – June 28 | 1 week after |
| Sweet Corn | Direct sow | May 7 – June 28 | 1 week after |
| Tomatoes | Set out | May 7 – June 28 | 1 week after |
| Winter Squash | Direct sow | May 7 – June 28 | 1 week after |
| Winter Squash | Set out | May 7 – June 28 | 1 week after |
| Zucchini | Direct sow | May 7 – June 28 | 1 week after |
| Zucchini | Set out | May 7 – June 28 | 1 week after |
| Cucumbers | Direct sow | May 14 – July 5 | 2 weeks after |
| Okra | Direct sow | May 14 – July 5 | 2 weeks after |
| Okra | Set out | May 14 – July 5 | 2 weeks after |
| Peppers | Set out | May 14 – July 5 | 2 weeks after |
| Southern Peas | Direct sow | May 14 – July 5 | 2 weeks after |
| Sweet Potato | Set out | May 14 – July 5 | 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 Denver-Aurora-Centennial, CO
Of 74 perennial fruits, nuts, berries, vegetables and herbs, 51 come through the winter in zone 6a and only 34 in zone 4a. That is a different garden at each end of the same metro.
| Zone | ZIPs | Survive | Fail for being too warm |
|---|---|---|---|
| 4a | 1 | 34 of 74 | 0 |
| 5a | 6 | 48 of 74 | 0 |
| 5b | 45 | 48 of 74 | 0 |
| 6a | 81 | 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.
Cautious — shortens the seasonMedian across stationsOptimistic
- Last spring freeze
- Plan to July 4 to be careful. Median April 30 – June 21 across 33 stations; April 15 is the optimistic end.
- First fall freeze
- Plan to August 17 to be careful. Median September 2 – October 14 across 33 stations; October 28 is the optimistic end.
NOAA publishes these as probabilities, not averages — the middle figure is a median, so half of years fall either side of it. The cautious end is the 10% tail: in roughly nine years in ten the freeze falls on the safe side of it.
The 33 stations behind these numbers
All 33 NOAA stations whose normals this page quotes, spanning about 144 km north to south. Every one is named with its identifier in the station list below — this page does not single one out, because no one station speaks for a whole metro area.
A relative sketch, not a map with a projection: longitude is adjusted for latitude so the shape is not stretched, and there is no basemap. For the one station nearest a specific address, with its real distance, use the ZIP lookup above.
Every figure above comes from these, and each is named so you can check it. Which station serves a given ZIP code, and how far away it is, varies across the metro — the table below gives it per ZIP code rather than this page averaging it.
| Station | NOAA ID | Last spring freeze | First fall freeze | Season |
|---|---|---|---|---|
| Bailey, CO | USC00050454 | June 16 | September 8 | 84 days |
| Boulder 14 W, CO | USW00094075 | June 21 | September 2 | 71 days |
| Brighton 3 SE, CO | USC00050950 | May 3 | October 7 | 155 days |
| Byers 5 Ene, CO | USC00051179 | May 13 | October 2 | 142 days |
| Cabin Creek, CO | USC00051186 | June 6 | September 19 | 103 days |
| Castle Rock, CO | USC00051401 | May 9 | October 2 | 143 days |
| Cheesman, CO | USC00051528 | May 17 | October 1 | 135 days |
| Cherry Creek Dam, CO | USC00051547 | May 7 | October 8 | 152 days |
| Coal Creek Canyon, CO | USC00051681 | June 5 | September 16 | 103 days |
| Denver Centennial AP, CO | USW00093067 | May 5 | October 8 | 154 days |
| Denver INTL AP, CO | USW00003017 | May 5 | October 9 | 156 days |
| Denver Water Dept, CO | USC00052223 | April 30 | October 12 | 165 days |
| Denver-Stapleton, CO | USW00023062 | May 4 | October 8 | 156 days |
| Eastonville 2 Nnw, CO | USC00052494 | May 29 | September 21 | 114 days |
| Elizabeth 2Nw, CO | USC00052631 | May 16 | October 2 | 137 days |
| Evergreen, CO | USC00052790 | May 23 | September 22 | 118 days |
| Fairplay S Park Rd, CO | USC00052816 | June 16 | September 9 | 83 days |
| Georgetown, CO | USC00053261 | May 30 | September 19 | 112 days |
| Grant, CO | USC00053530 | June 15 | September 9 | 84 days |
| Karval, CO | USC00054444 | May 9 | October 6 | 149 days |
| Kassler, CO | USC00054452 | May 8 | October 3 | 147 days |
| Lake George 8 SW, CO | USC00054742 | June 2 | September 19 | 108 days |
| Lakewood, CO | USC00054762 | May 3 | October 7 | 155 days |
| Limon Wsmo, CO | USW00093010 | May 21 | September 26 | 127 days |
| Marston Fltr Plt, CO | USC00055402 | May 2 | October 11 | 160 days |
| Matheson 8 SE, CO | USC00055427 | May 12 | October 2 | 141 days |
| Monument, CO | USC00055734 | May 14 | October 1 | 138 days |
| Northglenn, CO | USC00055984 | May 2 | October 11 | 160 days |
| Parker, CO | USC00056323 | May 9 | October 3 | 145 days |
| Ralston Rsvr, CO | USC00056816 | May 3 | October 14 | 161 days |
| Roxborough SP, CO | USC00057249 | May 16 | October 1 | 136 days |
| Strontia Springs Dam, CO | USC00058022 | May 16 | September 29 | 132 days |
| Wheat Ridge 2, CO | USC00058995 | May 5 | October 5 | 151 days |
These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.
Every ZIP code in Denver-Aurora-Centennial, CO
Zones are published per ZIP code, not per metro area, so this is the exact answer rather than the metro area's average. The station column is the nearest one to that ZIP code's centroid and how far away it is — the same figure the tools use, shown here so you can see which ZIP codes are well covered and which are reaching.
| ZIP code | USDA zone | Nearest NOAA station | Distance |
|---|---|---|---|
| 80002 | 6a | Wheat Ridge 2, CO | 2.2 km |
| 80003 | 6a | Wheat Ridge 2, CO | 7.2 km |
| 80004 | 6a | Wheat Ridge 2, CO | 4.3 km |
| 80005 | 6a | Wheat Ridge 2, CO | 8.6 km |
| 80007 | 6a | Ralston Rsvr, CO | 5.2 km |
| 80010 | 6a | Denver-Stapleton, CO | 2.8 km |
| 80011 | 6a | Denver-Stapleton, CO | 7.1 km |
| 80012 | 6a | Denver-Stapleton, CO | 7.6 km |
| 80013 | 6a | Cherry Creek Dam, CO | 6.9 km |
| 80014 | 6a | Cherry Creek Dam, CO | 4.2 km |
| 80015 | 6a | Cherry Creek Dam, CO | 3.3 km |
| 80016 | 6a | Parker, CO | 9.1 km |
| 80017 | 6a | Cherry Creek Dam, CO | 9.5 km |
| 80018 | 6a | Denver INTL AP, CO | 14.8 km |
| 80019 | 6a | Denver INTL AP, CO | 6.5 km |
| 80020 | 6a | Northglenn, CO | 6.3 km |
| 80021 | 6a | Northglenn, CO | 8.6 km |
| 80022 | 6a | Brighton 3 SE, CO | 10.0 km |
| 80023 | 6a | Northglenn, CO | 8.6 km |
| 80024 | 6a | Denver-Stapleton, CO | 9.9 km |
| 80030 | 6a | Northglenn, CO | 7.8 km |
| 80031 | 6a | Northglenn, CO | 3.5 km |
| 80033 | 6a | Wheat Ridge 2, CO | 1.1 km |
| 80045 | 6a | Denver-Stapleton, CO | 3.3 km |
| 80101 | 5b | Limon Wsmo, CO | 31.2 km |
| 80102 | 6a | Denver INTL AP, CO | 21.7 km |
| 80103 | 5b | Byers 5 Ene, CO | 6.3 km |
| 80104 | 5b | Castle Rock, CO | 14.2 km |
| 80105 | 5b | Byers 5 Ene, CO | 18.0 km |
| 80106 | 5b | Eastonville 2 Nnw, CO | 11.2 km |
| 80107 | 5b | Elizabeth 2Nw, CO | 6.0 km |
| 80108 | 5b | Castle Rock, CO | 5.9 km |
| 80109 | 5b | Castle Rock, CO | 4.3 km |
| 80110 | 6a | Marston Fltr Plt, CO | 5.4 km |
| 80111 | 6a | Cherry Creek Dam, CO | 4.6 km |
| 80112 | 6a | Denver Centennial AP, CO | 1.4 km |
| 80113 | 6a | Marston Fltr Plt, CO | 9.0 km |
| 80116 | 5b | Elizabeth 2Nw, CO | 9.7 km |
| 80117 | 5b | Elizabeth 2Nw, CO | 20.6 km |
| 80118 | 5b | Monument, CO | 9.8 km |
| 80120 | 6a | Marston Fltr Plt, CO | 5.5 km |
| 80121 | 6a | Marston Fltr Plt, CO | 9.6 km |
| 80122 | 6a | Denver Centennial AP, CO | 9.2 km |
| 80123 | 6a | Marston Fltr Plt, CO | 0.7 km |
| 80124 | 6a | Denver Centennial AP, CO | 5.5 km |
| 80125 | 5b | Kassler, CO | 2.8 km |
| 80126 | 6a | Denver Centennial AP, CO | 10.3 km |
| 80127 | 5b | Kassler, CO | 7.5 km |
| 80128 | 6a | Marston Fltr Plt, CO | 6.8 km |
| 80129 | 6a | Marston Fltr Plt, CO | 9.5 km |
| 80130 | 6a | Denver Centennial AP, CO | 7.9 km |
| 80131 | 5b | Roxborough SP, CO | 7.5 km |
| 80134 | 5b | Parker, CO | 4.3 km |
| 80135 | 5b | Cheesman, CO | 11.1 km |
| 80136 | 5b | Byers 5 Ene, CO | 14.2 km |
| 80137 | 6a | Denver INTL AP, CO | 14.5 km |
| 80138 | 5b | Parker, CO | 6.8 km |
| 80202 | 6a | Denver Water Dept, CO | 2.6 km |
| 80203 | 6a | Denver Water Dept, CO | 2.2 km |
| 80204 | 6a | Denver Water Dept, CO | 1.2 km |
| 80205 | 6a | Denver Water Dept, CO | 5.0 km |
| 80206 | 6a | Denver Water Dept, CO | 4.8 km |
| 80207 | 6a | Denver-Stapleton, CO | 4.0 km |
| 80209 | 6a | Denver Water Dept, CO | 4.4 km |
| 80210 | 6a | Denver Water Dept, CO | 7.1 km |
| 80211 | 6a | Denver Water Dept, CO | 4.3 km |
| 80212 | 6a | Denver Water Dept, CO | 5.8 km |
| 80214 | 6a | Lakewood, CO | 4.5 km |
| 80215 | 6a | Lakewood, CO | 0.6 km |
| 80216 | 6a | Denver Water Dept, CO | 7.6 km |
| 80218 | 6a | Denver Water Dept, CO | 3.2 km |
| 80219 | 6a | Denver Water Dept, CO | 4.5 km |
| 80220 | 6a | Denver-Stapleton, CO | 5.2 km |
| 80221 | 6a | Northglenn, CO | 9.2 km |
| 80222 | 6a | Denver Water Dept, CO | 9.4 km |
| 80223 | 6a | Denver Water Dept, CO | 3.8 km |
| 80224 | 6a | Denver-Stapleton, CO | 9.1 km |
| 80226 | 6a | Lakewood, CO | 5.0 km |
| 80227 | 6a | Marston Fltr Plt, CO | 5.8 km |
| 80228 | 6a | Lakewood, CO | 7.5 km |
| 80229 | 6a | Northglenn, CO | 6.9 km |
| 80230 | 6a | Denver-Stapleton, CO | 5.1 km |
| 80231 | 6a | Cherry Creek Dam, CO | 6.9 km |
| 80232 | 6a | Lakewood, CO | 7.3 km |
| 80233 | 6a | Northglenn, CO | 5.9 km |
| 80234 | 6a | Northglenn, CO | 1.5 km |
| 80235 | 6a | Marston Fltr Plt, CO | 3.6 km |
| 80236 | 6a | Marston Fltr Plt, CO | 4.1 km |
| 80237 | 6a | Cherry Creek Dam, CO | 6.2 km |
| 80238 | 6a | Denver-Stapleton, CO | 1.8 km |
| 80239 | 6a | Denver-Stapleton, CO | 4.2 km |
| 80241 | 6a | Northglenn, CO | 6.0 km |
| 80246 | 6a | Denver Water Dept, CO | 7.2 km |
| 80247 | 6a | Denver-Stapleton, CO | 7.3 km |
| 80249 | 6a | Denver INTL AP, CO | 4.1 km |
| 80260 | 6a | Northglenn, CO | 3.7 km |
| 80266 | 6a | Denver-Stapleton, CO | 4.0 km |
| 80290 | 6a | Denver Water Dept, CO | 2.5 km |
| 80401 | 5b | Lakewood, CO | 10.4 km |
| 80403 | 5b | Ralston Rsvr, CO | 7.0 km |
| 80420 | 5a | Fairplay S Park Rd, CO | 15.5 km |
| 80421 | 5b | Bailey, CO | 6.5 km |
| 80422 | 5b | Coal Creek Canyon, CO | 13.8 km |
| 80425 | 5b | Strontia Springs Dam, CO | 11.9 km |
| 80427 | 5b | Coal Creek Canyon, CO | 16.5 km |
| 80432 | 5a | Fairplay S Park Rd, CO | 13.5 km |
| 80433 | 5b | Evergreen, CO | 15.6 km |
| 80436 | 5b | Georgetown, CO | 9.8 km |
| 80438 | 5a | Georgetown, CO | 9.3 km |
| 80439 | 5b | Evergreen, CO | 10.7 km |
| 80440 | 5b | Fairplay S Park Rd, CO | 11.3 km |
| 80444 | 5a | Cabin Creek, CO | 3.4 km |
| 80448 | 5b | Grant, CO | 13.5 km |
| 80449 | 4a | Lake George 8 SW, CO | 27.8 km |
| 80452 | 5b | Georgetown, CO | 8.8 km |
| 80453 | 5b | Evergreen, CO | 6.9 km |
| 80454 | 5b | Evergreen, CO | 5.9 km |
| 80456 | 5a | Grant, CO | 16.7 km |
| 80457 | 5b | Evergreen, CO | 1.9 km |
| 80465 | 5b | Evergreen, CO | 9.9 km |
| 80470 | 5b | Bailey, CO | 13.4 km |
| 80474 | 5b | Boulder 14 W, CO | 12.7 km |
| 80475 | 5b | Grant, CO | 8.2 km |
| 80476 | 5a | Cabin Creek, CO | 10.9 km |
| 80601 | 5b | Brighton 3 SE, CO | 3.2 km |
| 80602 | 6a | Brighton 3 SE, CO | 6.7 km |
| 80603 | 5b | Denver INTL AP, CO | 13.2 km |
| 80640 | 5b | Brighton 3 SE, CO | 7.3 km |
| 80820 | 5b | Lake George 8 SW, CO | 16.7 km |
| 80827 | 5b | Lake George 8 SW, CO | 16.6 km |
| 80830 | 5b | Matheson 8 SE, CO | 6.0 km |
| 80832 | 5b | Karval, CO | 26.0 km |
| 80835 | 5b | Matheson 8 SE, CO | 18.2 km |
ZIP-code positions are area centroids, so a large rural ZIP code's listed distance is measured from the middle of its area rather than from any particular address in it.
Your own ZIP
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 Denver-Aurora-Centennial, CO 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.
Other places to compare
Gardening in Colorado — zones 4a– 7a covers the whole state: how its 520 ZIP codes divide between 7 hardiness zones, and the freeze dates across every NOAA station in it.
Other metro areas in CO:
- Colorado Springs, CO Zones 5a–6a
- Greeley, CO Zones 5a–5b
- Fort Collins-Loveland, CO Zones 5a–5b
- Boulder, CO Zones 5b–6a
- Grand Junction, CO Zones 5b–7a
- Pueblo, CO Zone 6a
Gear
If you want to act on this
Each link opens an Amazon search rather than a product we picked. We have not tested these and do not rank them — the search is the honest version, and you choose.
- Trunk wrapZone 4a is cold enough that winter sun on a young trunk does more damage than the cold does.
- Row cover and frost clothThe season here closes at the first fall freeze dated above — a cover buys back some of those days at the end.
- MulchFor the perennials nearest their cold limit in zone 4a, where an insulated crown is what decides whether they come back.
As an Amazon Associate we earn from qualifying purchases. That costs you nothing extra, and it buys no influence over anything on this site: the dates come from NOAA normals and the zones from the USDA, and no product affects either.
Sources
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.