One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A way of getting a good idea when to plant watermelon is to examine the USDA zone info for San Ramon.

Planting Calendar for Watermelon

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

Watermelon do not do well in cold weather which tells us that you really should wait until it warms up after the last frost before you can plant them.

The earliest that you can plant watermelon in San Ramon is March. However, you really should wait until April 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. If you wait 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

The average date of last frost is February 15 in San Ramon. You should expect an average low temperature of 25°F in the coldest months of winter.

Always keep in mind that USDA zone info for San Ramon is just an average and the actual date of last frost changes from year to year. Half of the time in San Ramon you get surprised by a frost after February 15 so just be sure to be ready to cover your watermelon if you have a surprise late frost.

USDA Zone Info for San Ramon

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in San Ramon

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