The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of getting a good idea when it's a good idea to plant watermelon is to check out the USDA zone info for Portland.

Planting Calendar for Watermelon

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

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

The earliest that you can plant watermelon in Portland is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant watermelon and expect a good harvest is probably August. 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 couple of weeks earlier.

Last Frost Date

On average all chance of frost has passed is on April 15 in Portland. You should expect an average low temperature of -15°F in the coldest months of winter.

Always keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Portland and it changes from year to year. Half of the time in Portland it frosts late in the year after April 15 so always be ready to cover your watermelon in the event of a late frost.

USDA Zone Info for Portland

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Portland

You may be interested in your other planting guides for Portland.