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

The USDA zone info for Washington can be looked at to determine when it's possible to plant pentas.

Planting Calendar for Pentas

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

You should not plant pentas until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant pentas in Washington 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 pentas and expect a good harvest is probably August. You probably don't want to wait any later than that or else your pentas may not have a chance to really do well. Starting your pentas indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Washington. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Washington may not be accurate from year to year the actual date of last frost is different every year. Since half of the time in Washington you get a frost after April 15 be ready to cover your pentas in the event of a surprise late frost.

USDA Zone Info for Washington

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 Washington

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