One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You will be able to determine when it's the best time to plant watermelon by looking at the USDA zone info for San Diego.

Planting Calendar for Watermelon

Frost tolerance for watermelon:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

It's not a good idea to plant watermelon until after the last frost when the weather gets warmer because they are not cold tolerant.

The earliest that you can plant watermelon in San Diego is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant watermelon and expect a good harvest is probably September. Any later than that and your watermelon may not have a chance to fully mature. If you are starting your watermelon indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average all chance of frost has passed is on January 31 in San Diego. In the coldest months of winter you should expect an average low temperature of 35°F.

It's important to remember that USDA zone info for San Diego is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in San Diego you get surprised by a frost after January 31 so just be sure to be ready to cover your watermelon in the event of a surprise late frost.

USDA Zone Info for San Diego

Here is the info for USDA Zone 10b.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	35°F
Highest Expected Low	40°F

This means that on a really cold year, the coldest it will get is 35°F. On most years you should be prepared to experience lows near 40°F.

Plants to Grow in San Diego

You may be interested in your other planting guides for San Diego.