The USDA Zone info is a great tool for gardeners to help us figure out 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.

One way of determining when it's the best time to plant xerianthemum is to use the USDA zone info for Zone 4a.

Planting Calendar for Xerianthemum

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

Since xerianthemum are barely cold tolerant you can plant them a bit earlier in the year than more sensitive plants.

The earliest that you can plant xerianthemum in Zone 4a 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 xerianthemum and expect a good harvest is probably August. If you wait any later than that and your xerianthemum may not have a chance to really do well. You can get started a few weeks earlier by starting your xerianthemum indoors.

Last Frost Date

The average date of last frost is May 15 in Zone 4a. In the coldest months of winter you should expect an average low temperature of -30°F.

Since the USDA zone info for Zone 4a is just an average the actual date of last frost changes from year to year. Since half of the time in Zone 4a there is a last frost after May 15 be ready to protect your xerianthemum if you have one of those late frosts.

USDA Zone Info for Zone 4a

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Zone 4a

You may be interested in your other planting guides for Zone 4a.