One of the best tools that you have as gardeners to help us estimate your gardening schedule is the 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 a good idea to plant watermelon by reviewing the USDA zone info for San Marcos.

Planting Calendar for Watermelon

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

Since watermelon require warm weather you need to wait until after the last frost before you can plant them.

The earliest that you can plant watermelon in San Marcos 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. You probably don't want to wait any later than that or else your watermelon may not have a chance to really do well. 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 January 31 in San Marcos. It might get as low as 30°F during the coldest months of winter.

Remember that USDA zone info for San Marcos is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in San Marcos you get surprised by a frost after January 31 so be sure to be ready to cover your watermelon in the event of one of those late frosts.

USDA Zone Info for San Marcos

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in San Marcos

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