The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The best time to plant asters in Zone 1a can be figured out by reviewing the USDA zone info.

Planting Calendar for Asters

Frost tolerance for asters:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

You can plant asters a bit earlier in the year because they are moderately cold tolerant.

The earliest that you can plant asters in Zone 1a is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant asters and expect a good harvest is probably July. You probably don't want to wait any later than that or else your asters may not have a chance to fully mature. Starting your asters indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

The average date of last frost is June 15 in Zone 1a. In the coldest months of winter you can expect an average low temperature of -60°F.

Remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Zone 1a and it will vary from year to year. Since half of the time in Zone 1a there is a last frost after June 15 be ready to protect your asters in the event of a surprise late frost.

USDA Zone Info for Zone 1a

Here is the info for USDA Zone 1a.

Average Date of Last Frost (spring)	June 15
Average Date of First Frost (fall)	July 15
Lowest Expected Low	-60°F
Highest Expected Low	-55°F

This means that on a really cold year, the coldest it will get is -60°F. On most years you should be prepared to experience lows near -55°F.

Plants to Grow in Zone 1a

You may be interested in your other planting guides for Zone 1a.