One of the best tools that you have as gardeners to help us figure out 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.

In National City you can estimate when to plant watermelon by referring to the USDA zone info.

Planting Calendar for Watermelon

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

Watermelon require warm weather which tells us that it's important to wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant watermelon in National City 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. If you wait any later than that and your watermelon may not have a chance to really do well. You can get started a little bit earlier by starting your watermelon indoors.

Last Frost Date

On average the last frost is on January 31 in National City. You can expect an average low temperature of 35°F in the coldest months of winter.

Since the USDA zone info for National City is just an average the actual date of last frost will vary from year to year. Half of the time in National City it frosts late in the year after January 31 so always be ready to protect your watermelon in the event of a surprise late frost.

USDA Zone Info for National City

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 National City

You may be interested in your other planting guides for National City.