When to plant watermelons in zone 9a
In zone 9a, where the last spring frost typically comes around March 2, start watermelons indoors February 7 to 21 and plant out March 14 to 28.
The zone 9a schedule for watermelons
- Start seeds indoors
- February 7 to 21
- Plant out
- March 14 to 28
- Sow outdoors
- March 14 to 28
- Soil warm enough (60°F), about
- March 14
- Safest planting date (10% frost risk)
- March 25
- First harvest, roughly
- May 13 to June 26
From the median frost dates of the NOAA stations assigned to the 1,736 ZIP codes in zone 9a, and the timing recommended by Cooperative Extension guides for watermelons.
Frost risk in zone 9a
Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 9a, the typical last frost ranges from about February 13 in the earliest tenth of ZIP codes to March 21 in the latest tenth, and the first fall frost from November 14 to December 9. For a typical place in the zone:
- February 4Risky: a later frost happens in 9 years out of 10
- March 2Typical: frost after this date in half of years
- March 25Safe: a later frost only 1 year in 10
Watermelons are killed by frost, so if you want to be safe, plant out after the safe date rather than the typical one, or be ready to cover plants on a cold night.
Your dates for watermelons
Set your ZIP code at the top of the page and we will work out when to plant watermelons where you live, from the frost records of the nearest NOAA weather station. Your ZIP code is remembered on this device only.
Watermelons in zone 9a cities
| City | Typical last frost | Start indoors | Plant out |
|---|---|---|---|
| Austin, TX | Feb 20 | Jan 29 to Feb 12 | Mar 5 to 19 |
| Seattle, WA | Mar 8 | May 2 to 16 | Jun 6 to 20 |
| Portland, OR | Mar 13 | Apr 14 to 28 | May 19 to Jun 2 |
| Tucson, AZ | Feb 5 | Feb 1 to 15 | Mar 8 to 22 |
| North Las Vegas, NV | Jan 20 | Feb 6 to 20 | Mar 13 to 27 |
| Baton Rouge, LA | Feb 25 | Jan 30 to Feb 13 | Mar 6 to 20 |
| Tallahassee, FL | Mar 11 | Feb 11 to 25 | Mar 18 to Apr 1 |
| Mobile, AL | Feb 21 | Jan 31 to Feb 14 | Mar 7 to 21 |
| Palmdale, CA | Mar 10 | Mar 10 to 24 | Apr 14 to 28 |
| Charleston, SC | Feb 4 | Feb 15 to Mar 1 | Mar 22 to Apr 5 |
| Savannah, GA | Mar 2 | Feb 9 to 23 | Mar 16 to 30 |
| Gainesville, FL | Mar 3 | Feb 3 to 17 | Mar 10 to 24 |
How to grow watermelonsAll zonesWatermelons in zone 8bWatermelons in zone 9bAbout zone 9a
Sources
- Growing Watermelon in the Home Garden · Iowa State University Extension and Outreach
- How to Grow Watermelon in Your Garden · Utah State University Extension
- Watermelon (HGIC factsheet) · Clemson Cooperative Extension Home & Garden Information Center
- Citrullus lanatus (Watermelon) · NC State Extension Gardener Plant Toolbox
- Florida Vegetable Gardening Guide (SP103/VH021) · University of Florida IFAS Extension
- Vegetable Planting Calendar for Maricopa County (AZ1005) · University of Arizona Cooperative Extension