Alaska
Planting zones in Kenai Peninsula Borough, Alaska
This borough spans USDA zones 4b to 6b, so there is no single zone for Kenai Peninsula Borough and anyone who gives you one is rounding. 33% of its ZIP codes are zone 5a; the rest are not.
Your ZIP code
Get the exact answer for your address
Everything above describes Kenai Peninsula Borough, Alaska 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 Kenai Peninsula Borough is closing
Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives September 1 – October 7 across the 12 NOAA stations serving this borough .
Your next season already has a date
The first job of it is 🧅 Green Onions, start indoors, around March 7 – April 17 — counted back from a last spring freeze of May 2 – June 12 here.
These are ranges across the whole borough. The ZIP lookup above gives the dates from your own nearest station instead.
All 12 stations agreeAt least one station
Every one of the 12 NOAA stations serving this borough counts June 12 – September 1 as growing season (81 days). Widening to any single station gives May 2 – October 7 (158 days).
That is a 77-day difference inside one borough — 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
Kenai Peninsula Borough covers 5 hardiness zones. A guide that gives the borough one zone has picked whichever is largest and rounded everyone else into it — fine for the 33% in zone 5a and wrong for the other 67%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 5a | 5 | 33% | |
| 4b | 4 | 27% | |
| 5b | 3 | 20% | |
| 6a | 2 | 13% | |
| 6b | 1 | 7% |
Zones are published per ZIP code, so yours is exact even though the borough's is not. The hardiness tool will tell you which one you are in.
Your freeze dates
Across the 12 NOAA stations serving this borough. 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 75–158 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 59.1–67.9 °F in June–August. Summer rain over the same months runs 4.6–12.5" 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 54% 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 64 °F summer afternoon drying the soil faster than a cool one.
Every ZIP code in Kenai Peninsula Borough
Zones are published per ZIP code, not per borough, so this is the exact answer rather than the borough'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 |
|---|---|---|---|
| 99556 | 6a | Homer 8 NW, AK | 10.5 km |
| 99568 | 5a | Sterling 6Sw, AK | 29.8 km |
| 99572 | 5a | Cooper Landing 5 W, AK | 4.8 km |
| 99603 | 6a | Homer AP, AK | 20.6 km |
| 99605 | 5b | Hope, AK | 9.1 km |
| 99610 | 4b | Soldotna 5Ssw, AK | 17.2 km |
| 99611 | 5a | Kenai 29 Ene, AK | 19.4 km |
| 99631 | 5a | Moose Pass 3Nw, AK | 15.6 km |
| 99635 | 4b | Big River Lakes, AK | 47.5 km |
| 99639 | 5b | Homer 8 NW, AK | 27.7 km |
| 99663 | 6b | Seldovia AP, AK | 6.4 km |
| 99664 | 5b | Seward AP, AK | 4.7 km |
| 99669 | 4b | Soldotna 5Ssw, AK | 9.2 km |
| 99672 | 4b | Sterling 6Sw, AK | 12.3 km |
| 99682 | 5a | Kenai 9N, AK | 58.5 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 Kenai Peninsula Borough
Every date below is anchored on the last spring freeze at each station and reported as a range across all 12 of them, because no one station speaks for the borough.
| Crop | Job | When | Offset |
|---|---|---|---|
| 🧅 Green Onions | Start indoors | March 7 – April 17 | 8 wk before |
| 🌶️ Peppers | Start indoors | March 7 – April 17 | 8 wk before |
| 🥦 Broccoli | Start indoors | March 21 – May 1 | 6 wk before |
| 🥬 Cabbage | Start indoors | March 21 – May 1 | 6 wk before |
| 🥬 Collards | Start indoors | March 21 – May 1 | 6 wk before |
| 🥬 Kale | Start indoors | March 21 – May 1 | 6 wk before |
| 🥬 Leaf Lettuce | Start indoors | March 21 – May 1 | 6 wk before |
| 🫛 Peas | Direct sow | March 21 – May 1 | 6 wk before |
| 🥬 Spinach | Direct sow | March 21 – May 1 | 6 wk before |
| 🍠 Sweet Potato | Start indoors | March 21 – May 1 | 6 wk before |
| 🍅 Tomatoes | Start indoors | March 21 – May 1 | 6 wk before |
| 🥬 Bok Choy | Start indoors | March 28 – May 8 | 5 wk before |
| 🥬 Kohlrabi | Start indoors | March 28 – May 8 | 5 wk before |
| 🥬 Swiss Chard | Start indoors | March 28 – May 8 | 5 wk before |
| 🥬 Arugula | Direct sow | April 4 – May 15 | 4 wk before |
| 🥬 Baby Salad Greens | Direct sow | April 4 – May 15 | 4 wk before |
| 🥕 Beets | Direct sow | April 4 – May 15 | 4 wk before |
| 🧅 Green Onions | Direct sow | April 4 – May 15 | 4 wk before |
| 🥬 Mustard Greens | Direct sow | April 4 – May 15 | 4 wk before |
| 🌶️ Okra | Start indoors | April 4 – May 15 | 4 wk before |
| 🌱 Radishes | Direct sow | April 4 – May 15 | 4 wk before |
| 🥔 Turnips | Direct sow | April 4 – May 15 | 4 wk before |
| 🥬 Cabbage | Set out | April 11 – May 22 | 3 wk before |
| 🥕 Carrots | Direct sow | April 11 – May 22 | 3 wk before |
| 🥬 Collards | Direct sow | April 11 – May 22 | 3 wk before |
| 🥬 Collards | Set out | April 11 – May 22 | 3 wk before |
| 🥒 Cucumbers | Start indoors | April 11 – May 22 | 3 wk before |
| 🧅 Green Onions | Set out | April 11 – May 22 | 3 wk before |
| 🥬 Kale | Direct sow | April 11 – May 22 | 3 wk before |
| 🥬 Kale | Set out | April 11 – May 22 | 3 wk before |
| 🥬 Kohlrabi | Direct sow | April 11 – May 22 | 3 wk before |
| 🥬 Kohlrabi | Set out | April 11 – May 22 | 3 wk before |
| 🥬 Leaf Lettuce | Direct sow | April 11 – May 22 | 3 wk before |
| 🎃 Pumpkins | Start indoors | April 11 – May 22 | 3 wk before |
| 🎃 Summer Squash | Start indoors | April 11 – May 22 | 3 wk before |
| 🎃 Winter Squash | Start indoors | April 11 – May 22 | 3 wk before |
| 🥒 Zucchini | Start indoors | April 11 – May 22 | 3 wk before |
| 🥬 Bok Choy | Direct sow | April 18 – May 29 | 2 wk before |
| 🥬 Bok Choy | Set out | April 18 – May 29 | 2 wk before |
| 🥦 Broccoli | Set out | April 18 – May 29 | 2 wk before |
| 🌿 Cilantro | Direct sow | April 18 – May 29 | 2 wk before |
| 🥬 Leaf Lettuce | Set out | April 18 – May 29 | 2 wk before |
| 🥬 Swiss Chard | Direct sow | April 18 – May 29 | 2 wk before |
| 🥬 Swiss Chard | Set out | April 18 – May 29 | 2 wk before |
| 🌿 Dill | Direct sow | April 25 – June 5 | 1 wk before |
| 🫘 Bush Beans | Direct sow | May 9 – June 19 | 1 wk after |
| 🥒 Cucumbers | Set out | May 9 – June 19 | 1 wk after |
| 🎃 Pumpkins | Direct sow | May 9 – June 19 | 1 wk after |
| 🎃 Pumpkins | Set out | May 9 – June 19 | 1 wk after |
| 🎃 Summer Squash | Direct sow | May 9 – June 19 | 1 wk after |
| 🎃 Summer Squash | Set out | May 9 – June 19 | 1 wk after |
| 🌽 Sweet Corn | Direct sow | May 9 – June 19 | 1 wk after |
| 🍅 Tomatoes | Set out | May 9 – June 19 | 1 wk after |
| 🎃 Winter Squash | Direct sow | May 9 – June 19 | 1 wk after |
| 🎃 Winter Squash | Set out | May 9 – June 19 | 1 wk after |
| 🥒 Zucchini | Direct sow | May 9 – June 19 | 1 wk after |
| 🥒 Zucchini | Set out | May 9 – June 19 | 1 wk after |
| 🥒 Cucumbers | Direct sow | May 16 – June 26 | 2 wk after |
| 🌶️ Okra | Direct sow | May 16 – June 26 | 2 wk after |
| 🌶️ Okra | Set out | May 16 – June 26 | 2 wk after |
| 🌶️ Peppers | Set out | May 16 – June 26 | 2 wk after |
| 🫘 Southern Peas | Direct sow | May 16 – June 26 | 2 wk after |
| 🍠 Sweet Potato | Set out | May 16 – June 26 | 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 Kenai Peninsula Borough
Zone 6a carries 51 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 July 7 to be careful. Median May 2 – June 12 across 12 stations; April 20 is the optimistic end.
- First fall freeze
- Plan to August 11 to be careful. Median September 1 – October 7 across 12 stations; October 23 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 12 stations behind these numbers
All 12 NOAA stations whose normals this page quotes, spanning about 162 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 borough.
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 borough'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 |
|---|---|---|---|---|
| Big River Lakes, AK | USC00500788 | May 7 | October 7 | 151 days |
| Cooper Landing 5 W, AK | USC00502149 | June 12 | September 1 | 78 days |
| Homer 8 NW, AK | USC00503672 | May 16 | September 30 | 136 days |
| Homer AP, AK | USW00025507 | May 10 | September 29 | 141 days |
| Hope, AK | USC00503720 | May 18 | September 24 | 127 days |
| Kenai 29 Ene, AK | USW00026563 | June 1 | September 8 | 94 days |
| Kenai 9N, AK | USC00504550 | May 18 | September 22 | 125 days |
| Moose Pass 3Nw, AK | USC00505894 | May 31 | September 8 | 99 days |
| Seldovia AP, AK | USW00025516 | May 10 | October 1 | 145 days |
| Seward AP, AK | USW00026438 | May 2 | October 7 | 158 days |
| Soldotna 5Ssw, AK | USC00508615 | June 11 | September 1 | 75 days |
| Sterling 6Sw, AK | USC00508731 | May 20 | September 21 | 123 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 borough. Every tool below answers for one ZIP code, which is the grain the underlying data is published at.
Other places to compare
Kenai Peninsula Borough sits in Alaska. That page carries the whole state's zone spread, its metro areas, and every other borough in it with a page here.
More of Alaska
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 borough: 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.