Maine
Planting zones in Somerset County, Maine
This county spans USDA zones 4b to 5b, so there is no single zone for Somerset County and anyone who gives you one is rounding. 80% of its ZIP codes are zone 5a; the rest are not.
Your ZIP code
Get the exact answer for your address
Everything above describes Somerset County, Maine 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 Somerset County is closing
Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives September 23 – October 10 across the 9 NOAA stations serving this county .
Your next season already has a date
The first job of it is 🧅 Green Onions, start indoors, around March 7 – March 31 — counted back from a last spring freeze of May 2 – May 26 here.
These are ranges across the whole county. The ZIP lookup above gives the dates from your own nearest station instead.
All 9 stations agreeAt least one station
Every one of the 9 NOAA stations serving this county counts May 26 – September 23 as growing season (120 days). Widening to any single station gives May 2 – October 10 (161 days).
That is a 41-day difference inside one county — 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
Somerset County covers 3 hardiness zones. A guide that gives the county one zone has picked whichever is largest and rounded everyone else into it — fine for the 80% in zone 5a and wrong for the other 20%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 5a | 20 | 80% | |
| 4b | 4 | 16% | |
| 5b | 1 | 4% |
Zones are published per ZIP code, so yours is exact even though the county's is not. The hardiness tool will tell you which one you are in.
Your freeze dates
Across the 9 NOAA stations serving this county. These are medians — half of years freeze later than the date shown — so treat the later end of each range as the cautious one.
The growing season runs 119–159 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 73.2–79.1 °F in June–August. Summer rain over the same months runs 10.8–13.2" across those 9 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 91% 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 77 °F summer afternoon drying the soil faster than a cool one.
Every ZIP code in Somerset County
Zones are published per ZIP code, not per county, so this is the exact answer rather than the county'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 |
|---|---|---|---|
| 04478 | 4b | Brassua Dam, ME | 8.3 km |
| 04911 | 5a | Madison, ME | 6.8 km |
| 04912 | 5a | Harmony, ME | 9.8 km |
| 04920 | 5a | Harmony, ME | 27.0 km |
| 04923 | 5a | Harmony, ME | 13.2 km |
| 04924 | 5a | Harmony, ME | 18.3 km |
| 04925 | 5a | Long Falls Dam, ME | 23.1 km |
| 04929 | 5a | Corinna, ME | 17.0 km |
| 04937 | 5a | Waterville Trtmt Plt, ME | 13.8 km |
| 04942 | 5a | Harmony, ME | 11.3 km |
| 04943 | 5a | Harmony, ME | 7.7 km |
| 04944 | 5a | Waterville Trtmt Plt, ME | 17.8 km |
| 04945 | 4b | Jackman, ME | 6.0 km |
| 04950 | 5a | Madison, ME | 7.7 km |
| 04957 | 5a | Madison, ME | 9.5 km |
| 04958 | 5a | Madison, ME | 12.8 km |
| 04961 | 4b | Long Falls Dam, ME | 8.3 km |
| 04965 | 5a | Corinna, ME | 13.1 km |
| 04967 | 5a | Harmony, ME | 21.6 km |
| 04971 | 5a | Harmony, ME | 11.7 km |
| 04975 | 5b | Waterville Trtmt Plt, ME | 12.1 km |
| 04976 | 5a | Madison, ME | 17.5 km |
| 04978 | 5a | New Sharon, ME | 15.9 km |
| 04979 | 5a | Madison, ME | 17.0 km |
| 04985 | 4b | Greenville Maine Forestry Svc, ME | 25.5 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.
When to start seeds in Somerset County
Every date below is anchored on the last spring freeze at each station and reported as a range across all 9 of them, because no one station speaks for the county.
| Crop | Job | When | Offset |
|---|---|---|---|
| 🧅 Green Onions | Start indoors | March 7 – March 31 | 8 wk before |
| 🌶️ Peppers | Start indoors | March 7 – March 31 | 8 wk before |
| 🥦 Broccoli | Start indoors | March 21 – April 14 | 6 wk before |
| 🥬 Cabbage | Start indoors | March 21 – April 14 | 6 wk before |
| 🥬 Collards | Start indoors | March 21 – April 14 | 6 wk before |
| 🥬 Kale | Start indoors | March 21 – April 14 | 6 wk before |
| 🥬 Leaf Lettuce | Start indoors | March 21 – April 14 | 6 wk before |
| 🫛 Peas | Direct sow | March 21 – April 14 | 6 wk before |
| 🥬 Spinach | Direct sow | March 21 – April 14 | 6 wk before |
| 🍠 Sweet Potato | Start indoors | March 21 – April 14 | 6 wk before |
| 🍅 Tomatoes | Start indoors | March 21 – April 14 | 6 wk before |
| 🥬 Bok Choy | Start indoors | March 28 – April 21 | 5 wk before |
| 🥬 Kohlrabi | Start indoors | March 28 – April 21 | 5 wk before |
| 🥬 Swiss Chard | Start indoors | March 28 – April 21 | 5 wk before |
| 🥬 Arugula | Direct sow | April 4 – April 28 | 4 wk before |
| 🥬 Baby Salad Greens | Direct sow | April 4 – April 28 | 4 wk before |
| 🥕 Beets | Direct sow | April 4 – April 28 | 4 wk before |
| 🧅 Green Onions | Direct sow | April 4 – April 28 | 4 wk before |
| 🥬 Mustard Greens | Direct sow | April 4 – April 28 | 4 wk before |
| 🌶️ Okra | Start indoors | April 4 – April 28 | 4 wk before |
| 🌱 Radishes | Direct sow | April 4 – April 28 | 4 wk before |
| 🥔 Turnips | Direct sow | April 4 – April 28 | 4 wk before |
| 🥬 Cabbage | Set out | April 11 – May 5 | 3 wk before |
| 🥕 Carrots | Direct sow | April 11 – May 5 | 3 wk before |
| 🥬 Collards | Direct sow | April 11 – May 5 | 3 wk before |
| 🥬 Collards | Set out | April 11 – May 5 | 3 wk before |
| 🥒 Cucumbers | Start indoors | April 11 – May 5 | 3 wk before |
| 🧅 Green Onions | Set out | April 11 – May 5 | 3 wk before |
| 🥬 Kale | Direct sow | April 11 – May 5 | 3 wk before |
| 🥬 Kale | Set out | April 11 – May 5 | 3 wk before |
| 🥬 Kohlrabi | Direct sow | April 11 – May 5 | 3 wk before |
| 🥬 Kohlrabi | Set out | April 11 – May 5 | 3 wk before |
| 🥬 Leaf Lettuce | Direct sow | April 11 – May 5 | 3 wk before |
| 🎃 Pumpkins | Start indoors | April 11 – May 5 | 3 wk before |
| 🎃 Summer Squash | Start indoors | April 11 – May 5 | 3 wk before |
| 🎃 Winter Squash | Start indoors | April 11 – May 5 | 3 wk before |
| 🥒 Zucchini | Start indoors | April 11 – May 5 | 3 wk before |
| 🥬 Bok Choy | Direct sow | April 18 – May 12 | 2 wk before |
| 🥬 Bok Choy | Set out | April 18 – May 12 | 2 wk before |
| 🥦 Broccoli | Set out | April 18 – May 12 | 2 wk before |
| 🌿 Cilantro | Direct sow | April 18 – May 12 | 2 wk before |
| 🥬 Leaf Lettuce | Set out | April 18 – May 12 | 2 wk before |
| 🥬 Swiss Chard | Direct sow | April 18 – May 12 | 2 wk before |
| 🥬 Swiss Chard | Set out | April 18 – May 12 | 2 wk before |
| 🌿 Dill | Direct sow | April 25 – May 19 | 1 wk before |
| 🫘 Bush Beans | Direct sow | May 9 – June 2 | 1 wk after |
| 🥒 Cucumbers | Set out | May 9 – June 2 | 1 wk after |
| 🎃 Pumpkins | Direct sow | May 9 – June 2 | 1 wk after |
| 🎃 Pumpkins | Set out | May 9 – June 2 | 1 wk after |
| 🎃 Summer Squash | Direct sow | May 9 – June 2 | 1 wk after |
| 🎃 Summer Squash | Set out | May 9 – June 2 | 1 wk after |
| 🌽 Sweet Corn | Direct sow | May 9 – June 2 | 1 wk after |
| 🍅 Tomatoes | Set out | May 9 – June 2 | 1 wk after |
| 🎃 Winter Squash | Direct sow | May 9 – June 2 | 1 wk after |
| 🎃 Winter Squash | Set out | May 9 – June 2 | 1 wk after |
| 🥒 Zucchini | Direct sow | May 9 – June 2 | 1 wk after |
| 🥒 Zucchini | Set out | May 9 – June 2 | 1 wk after |
| 🥒 Cucumbers | Direct sow | May 16 – June 9 | 2 wk after |
| 🌶️ Okra | Direct sow | May 16 – June 9 | 2 wk after |
| 🌶️ Okra | Set out | May 16 – June 9 | 2 wk after |
| 🌶️ Peppers | Set out | May 16 – June 9 | 2 wk after |
| 🫘 Southern Peas | Direct sow | May 16 – June 9 | 2 wk after |
| 🍠 Sweet Potato | Set out | May 16 – June 9 | 2 wk after |
Offsets are published guidance; the dates they land on are computed from measured NOAA normals. The seed-starting tool does this for your own ZIP code and counts the days.
What survives the winter changes across Somerset County
Zone 5a carries 48 of 74 perennial edibles; zone 4b carries 34. The best number is not always the warmest zone — the count peaks in the middle and falls both ways, because the warm end loses plants to insufficient winter chill and summer heat, not to cold.
Hardiness ranges are a judgement, published by growers rather than measured; the zone they are compared against is measured. On a warm-end verdict, check with your local extension service — a coastal zone 8 and an inland zone 8 are not the same summer.
Cautious — shortens the seasonMedian across stationsOptimistic
- Last spring freeze
- Plan to June 7 to be careful. Median May 2 – May 26 across 9 stations; April 23 is the optimistic end.
- First fall freeze
- Plan to September 8 to be careful. Median September 23 – October 10 across 9 stations; October 27 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 9 stations behind these numbers
All 9 NOAA stations whose normals this page quotes, spanning about 126 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 county.
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.
These are the stations this county's ZIP codes actually cite as nearest — not a claim that each one sits inside its boundary, since a rural ZIP legitimately reaches over it. Every figure above comes from them, and each is named so you can check it.
| Station | NOAA ID | Last spring freeze | First fall freeze | Season |
|---|---|---|---|---|
| Brassua Dam, ME | USC00170814 | May 23 | September 29 | 128 days |
| Corinna, ME | USC00171628 | May 8 | October 3 | 148 days |
| Greenville Maine Forestry Svc, ME | USW00094626 | May 7 | October 9 | 153 days |
| Harmony, ME | USC00173567 | May 11 | October 1 | 141 days |
| Jackman, ME | USC00174086 | May 26 | September 23 | 119 days |
| Long Falls Dam, ME | USC00174781 | May 13 | September 30 | 138 days |
| Madison, ME | USC00174927 | May 8 | October 5 | 149 days |
| New Sharon, ME | USC00175736 | May 7 | October 2 | 146 days |
| Waterville Trtmt Plt, ME | USC00179151 | May 2 | October 10 | 159 days |
These are medians, not averages — NOAA publishes freeze dates as a probability distribution, and half of years freeze later than the date shown.
Your own ZIP
Work out your own dates
This page describes a whole county. Every tool below answers for one ZIP code, which is the grain the underlying data is published at.
Other places to compare
Somerset County sits in Maine. That page carries the whole state's zone spread, its metro areas, and every other county in it with a page here.
More of Maine
- Waldo County, ME 5a–6a
- Franklin County, ME 4b–5a
- Piscataquis County, ME 4a–5a
- Aroostook County, ME 3b–5a
- Hancock County, ME 5a–6b
- Oxford County, ME 4b–5b
- Washington County, ME 4b–6a
- Kennebec County, ME 5a–5b
- Lincoln County, ME 5b–6b
Counties with the same zones — 4b–5b
Matched on the exact zone set, not a dominant zone, so the winter answer on these pages really is the same one as here.
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 4b 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 4b, 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
Hardiness zones are the USDA 2023 Plant Hardiness Zone Map, published per ZIP code by PRISM at Oregon State. Freeze dates and growing-season lengths are NOAA 1991–2020 Climate Normals, taken per station and cited above by name and NOAA ID.
County boundaries come from the Census ZCTA-to-county relation, which is what places each ZIP code — and which treats parishes, boroughs and census areas as county equivalents. No station is chosen to represent this county: every range above is taken across all of them and the count is stated, because picking one would be a judgement dressed as a measurement.