Utah
Planting zones in San Juan County, Utah
This county spans USDA zones 6b to 8a, so there is no single zone for San Juan County and anyone who gives you one is rounding. 50% of its ZIP codes are zone 7a; the rest are not.
Your ZIP code
Get the exact answer for your address
Everything above describes San Juan County, Utah 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 San Juan County is closing
Nothing in the 32-crop table still has time to mature here. The first fall freeze normally arrives October 2 – November 10 across the 8 NOAA stations serving this county .
Your next season already has a date
The first job of it is 🧅 Green Onions, start indoors, around January 28 – March 24 — counted back from a last spring freeze of March 25 – May 19 here.
These are ranges across the whole county. The ZIP lookup above gives the dates from your own nearest station instead.
All 8 stations agreeAt least one station
Every one of the 8 NOAA stations serving this county counts May 19 – October 2 as growing season (136 days). Widening to any single station gives March 25 – November 10 (230 days).
That is a 94-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
San Juan County covers 4 hardiness zones. A guide that gives the county one zone has picked whichever is largest and rounded everyone else into it — fine for the 50% in zone 7a and wrong for the other 50%. Here is the actual split.
| Zone | ZIP codes | Share | |
|---|---|---|---|
| 7a | 4 | 50% | |
| 8a | 2 | 25% | |
| 6b | 1 | 13% | |
| 7b | 1 | 13% |
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 8 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 133–227 days depending which station you are nearest, as published by NOAA rather than computed from the dates above. Summer highs average 82.7–96.7 °F in June–August. That is past the point where tomato and pepper pollen fails and cool-season greens bolt, so in this county heat decides as much as frost does. Summer rain over the same months runs 1.3–3.7" across those 7 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 17% of it, so a summer garden here is watered rather than rained on. The inches are NOAA's published normals; the inch a week is a rule of thumb, and it takes no account of a 93 °F summer afternoon drying the soil faster than a cool one.
Every ZIP code in San Juan 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 |
|---|---|---|---|
| 84511 | 7a | Blanding, UT | 11.5 km |
| 84512 | 7a | Bluff, UT | 12.6 km |
| 84530 | 7a | La Sal 1Sw, UT | 13.6 km |
| 84531 | 7b | Mexican Hat, UT | 10.5 km |
| 84533 | 8a | Bullfrog Basin, UT | 20.8 km |
| 84534 | 7a | Hovenweep Nm, UT | 25.4 km |
| 84535 | 6b | Monticello 2E, UT | 2.8 km |
| 84536 | 8a | Monument Valley, AZ | 18.4 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 San Juan County
Every date below is anchored on the last spring freeze at each station and reported as a range across all 8 of them, because no one station speaks for the county.
| Crop | Job | When | Offset |
|---|---|---|---|
| 🧅 Green Onions | Start indoors | January 28 – March 24 | 8 wk before |
| 🌶️ Peppers | Start indoors | January 28 – March 24 | 8 wk before |
| 🥦 Broccoli | Start indoors | February 11 – April 7 | 6 wk before |
| 🥬 Cabbage | Start indoors | February 11 – April 7 | 6 wk before |
| 🥬 Collards | Start indoors | February 11 – April 7 | 6 wk before |
| 🥬 Kale | Start indoors | February 11 – April 7 | 6 wk before |
| 🥬 Leaf Lettuce | Start indoors | February 11 – April 7 | 6 wk before |
| 🫛 Peas | Direct sow | February 11 – April 7 | 6 wk before |
| 🥬 Spinach | Direct sow | February 11 – April 7 | 6 wk before |
| 🍠 Sweet Potato | Start indoors | February 11 – April 7 | 6 wk before |
| 🍅 Tomatoes | Start indoors | February 11 – April 7 | 6 wk before |
| 🥬 Bok Choy | Start indoors | February 18 – April 14 | 5 wk before |
| 🥬 Kohlrabi | Start indoors | February 18 – April 14 | 5 wk before |
| 🥬 Swiss Chard | Start indoors | February 18 – April 14 | 5 wk before |
| 🥬 Arugula | Direct sow | February 25 – April 21 | 4 wk before |
| 🥬 Baby Salad Greens | Direct sow | February 25 – April 21 | 4 wk before |
| 🥕 Beets | Direct sow | February 25 – April 21 | 4 wk before |
| 🧅 Green Onions | Direct sow | February 25 – April 21 | 4 wk before |
| 🥬 Mustard Greens | Direct sow | February 25 – April 21 | 4 wk before |
| 🌶️ Okra | Start indoors | February 25 – April 21 | 4 wk before |
| 🌱 Radishes | Direct sow | February 25 – April 21 | 4 wk before |
| 🥔 Turnips | Direct sow | February 25 – April 21 | 4 wk before |
| 🥬 Cabbage | Set out | March 4 – April 28 | 3 wk before |
| 🥕 Carrots | Direct sow | March 4 – April 28 | 3 wk before |
| 🥬 Collards | Direct sow | March 4 – April 28 | 3 wk before |
| 🥬 Collards | Set out | March 4 – April 28 | 3 wk before |
| 🥒 Cucumbers | Start indoors | March 4 – April 28 | 3 wk before |
| 🧅 Green Onions | Set out | March 4 – April 28 | 3 wk before |
| 🥬 Kale | Direct sow | March 4 – April 28 | 3 wk before |
| 🥬 Kale | Set out | March 4 – April 28 | 3 wk before |
| 🥬 Kohlrabi | Direct sow | March 4 – April 28 | 3 wk before |
| 🥬 Kohlrabi | Set out | March 4 – April 28 | 3 wk before |
| 🥬 Leaf Lettuce | Direct sow | March 4 – April 28 | 3 wk before |
| 🎃 Pumpkins | Start indoors | March 4 – April 28 | 3 wk before |
| 🎃 Summer Squash | Start indoors | March 4 – April 28 | 3 wk before |
| 🎃 Winter Squash | Start indoors | March 4 – April 28 | 3 wk before |
| 🥒 Zucchini | Start indoors | March 4 – April 28 | 3 wk before |
| 🥬 Bok Choy | Direct sow | March 11 – May 5 | 2 wk before |
| 🥬 Bok Choy | Set out | March 11 – May 5 | 2 wk before |
| 🥦 Broccoli | Set out | March 11 – May 5 | 2 wk before |
| 🌿 Cilantro | Direct sow | March 11 – May 5 | 2 wk before |
| 🥬 Leaf Lettuce | Set out | March 11 – May 5 | 2 wk before |
| 🥬 Swiss Chard | Direct sow | March 11 – May 5 | 2 wk before |
| 🥬 Swiss Chard | Set out | March 11 – May 5 | 2 wk before |
| 🌿 Dill | Direct sow | March 18 – May 12 | 1 wk before |
| 🫘 Bush Beans | Direct sow | April 1 – May 26 | 1 wk after |
| 🥒 Cucumbers | Set out | April 1 – May 26 | 1 wk after |
| 🎃 Pumpkins | Direct sow | April 1 – May 26 | 1 wk after |
| 🎃 Pumpkins | Set out | April 1 – May 26 | 1 wk after |
| 🎃 Summer Squash | Direct sow | April 1 – May 26 | 1 wk after |
| 🎃 Summer Squash | Set out | April 1 – May 26 | 1 wk after |
| 🌽 Sweet Corn | Direct sow | April 1 – May 26 | 1 wk after |
| 🍅 Tomatoes | Set out | April 1 – May 26 | 1 wk after |
| 🎃 Winter Squash | Direct sow | April 1 – May 26 | 1 wk after |
| 🎃 Winter Squash | Set out | April 1 – May 26 | 1 wk after |
| 🥒 Zucchini | Direct sow | April 1 – May 26 | 1 wk after |
| 🥒 Zucchini | Set out | April 1 – May 26 | 1 wk after |
| 🥒 Cucumbers | Direct sow | April 8 – June 2 | 2 wk after |
| 🌶️ Okra | Direct sow | April 8 – June 2 | 2 wk after |
| 🌶️ Okra | Set out | April 8 – June 2 | 2 wk after |
| 🌶️ Peppers | Set out | April 8 – June 2 | 2 wk after |
| 🫘 Southern Peas | Direct sow | April 8 – June 2 | 2 wk after |
| 🍠 Sweet Potato | Set out | April 8 – June 2 | 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 San Juan County
Zone 7a carries 58 of 74 perennial edibles; zone 6b carries 51. 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 6 to be careful. Median March 25 – May 19 across 8 stations; March 8 is the optimistic end.
- First fall freeze
- Plan to September 20 to be careful. Median October 2 – November 10 across 8 stations; November 20 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 8 stations behind these numbers
All 8 NOAA stations whose normals this page quotes, spanning about 146 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 |
|---|---|---|---|---|
| Blanding, UT | USC00420738 | April 28 | October 21 | 174 days |
| Bluff, UT | USC00420788 | April 24 | October 13 | 172 days |
| Bullfrog Basin, UT | USC00421020 | March 25 | November 10 | 227 days |
| Hovenweep Nm, UT | USC00424100 | May 2 | October 10 | 159 days |
| La Sal 1Sw, UT | USC00424947 | May 17 | October 6 | 141 days |
| Mexican Hat, UT | USC00425582 | April 11 | October 30 | 201 days |
| Monticello 2E, UT | USC00425805 | May 19 | October 2 | 133 days |
| Monument Valley, AZ | USC00025665 | April 10 | November 1 | 205 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
San Juan County sits in Utah. That page carries the whole state's zone spread, its metro areas, and every other county in it with a page here.
More of Utah
- Uintah County, UT 5b–6a
- Kane County, UT 6a–7a
- Piute County, UT 5b–6a
- Wayne County, UT 6a, 7a
- Box Elder County, UT 6a–7a
- Sanpete County, UT 5b–6b
- Duchesne County, UT 5a–6a
- Sevier County, UT 6a
- Millard County, UT 5b–6b
- Iron County, UT 5b–7a
- Emery County, UT 6a–6b
- Summit County, UT 5a–6a
Counties with the same zones — 6b–8a
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.
- Shade clothSummer highs here average 93 °F, at or above the 90 °F point where lettuce and spinach bolt and tomato pollen fails.
- 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 6b, 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.