Maple Valley, WA planting zone & frost dates
Maple Valley is in USDA hardiness zone 8b. The last spring frost usually comes around April 20 and the first fall frost around October 25, for a growing season of about 187 days.
Planting calendar for Maple Valley
Dates are counted from the average last spring frost (April 20) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Feb 23 – Mar 9 Transplant outdoors: Apr 27 – May 4 |
| Peppers | Start seeds indoors: Feb 9 – Feb 23 Transplant outdoors: May 4 – May 11 |
| Eggplant | Start seeds indoors: Feb 9 – Feb 23 Transplant outdoors: May 4 – May 11 |
| Broccoli | Start seeds indoors: Feb 9 – Feb 23 Transplant outdoors: Mar 23 – Apr 6 |
| Cabbage | Start seeds indoors: Feb 9 – Feb 23 Transplant outdoors: Mar 23 – Apr 6 |
| Onions (sets) | Plant outdoors: Mar 23 – Apr 6 |
| Peas | Sow outdoors: Mar 9 – Mar 23 |
| Spinach | Sow outdoors: Mar 9 – Mar 23 |
| Lettuce | Sow outdoors: Mar 23 – Apr 6 |
| Carrots | Sow outdoors: Mar 23 – Apr 6 |
| Potatoes | Plant outdoors: Mar 23 – Apr 6 |
| Beans | Sow outdoors: Apr 27 – May 4 |
| Sweet corn | Sow outdoors: Apr 27 – May 4 |
| Cucumbers | Sow outdoors: Apr 27 – May 4 |
| Squash & zucchini | Sow outdoors: Apr 27 – May 4 |
| Basil | Start seeds indoors: Mar 9 – Mar 23 Transplant outdoors: Apr 27 – May 4 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 30 (8 weeks before the average first fall frost on Oct 25).
Useful for zone 8b gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Mar 31 | Apr 20 | May 10 |
| First 32°F frost in fall is before | Nov 12 | Oct 25 | Oct 5 |
How to read it: in spring there is a 10% chance of a frost after May 10, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 5. A hard freeze (28°F) usually ends around March 24.
Hardiness zone by ZIP code in Maple Valley
- 98038 zone 8b
Nearby cities
- Lake Morton-Berrydale zone 8b, last frost Apr 20
- Covington zone 8b, last frost Mar 20
- East Renton Highlands zone 8b, last frost Mar 13
- Fairwood zone 8b, last frost Mar 13
- East Hill-Meridian zone 8b, last frost Mar 20
- Issaquah zone 8b, last frost Mar 13
- Lea Hill zone 8b, last frost Mar 20
- Klahanie zone 8b, last frost Mar 30
Questions
What growing zone is Maple Valley, WA?
Maple Valley is in USDA Plant Hardiness Zone 8b (average extreme winter low 15°F to 20°F), according to the USDA 2023 map.
When is the last frost in Maple Valley?
The average last spring frost (32°F) in Maple Valley is April 20. There is still a 10% chance of frost until May 10.
When can I plant tomatoes in Maple Valley?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 27 – May 4. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Landsburg, WA (USC00454486), 6.6 km (4.1 mi) from the city center, elevation 163 m, based on 23 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.