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

The USDA zone info for Washington should be looked at to figure out when it's a good idea to plant alternaria.

Planting Calendar for Alternaria

Frost tolerance for alternaria:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since alternaria are not cold tolerant it is important to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant alternaria 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 alternaria and expect a good harvest is probably August. If you wait any later than that and your alternaria may not have a chance to fully mature. Starting your alternaria indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Washington. You can expect an average low temperature of -10°F in the coldest months of winter.

Always keep in mind that USDA zone info for Washington may not be accurate from year to year and the actual date of last frost changes from year to year. Since half of the time in Washington last frost occurs after April 15 be ready to cover your alternaria in the event of one of those late frosts.

USDA Zone Info for Washington

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Washington

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