One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

One way of figuring out when to plant hardy asters is to consult the USDA zone info for Washington.

Planting Calendar for Hardy Asters

Frost tolerance for hardy asters:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant hardy asters slightly earlier in the year because they are barely cold tolerant.

The earliest that you can plant hardy asters in Washington is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant hardy asters and expect a good harvest is probably August. Any later than that and your hardy asters may not have a chance to fully mature. You can get started a few weeks earlier by starting your hardy asters indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Washington. It might get as low as -10°F during the coldest months of winter.

Since the USDA zone info for Washington is just an average the actual date of last frost will vary from year to year. Since half of the time in Washington last frost occurs after April 15 be ready to protect your hardy asters if you have 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.