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

A common way of getting a good idea when it's a good idea to plant ajuga is to consult the USDA zone info for Zone 4b.

Planting Calendar for Ajuga

Frost tolerance for ajuga:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since ajuga are one of those plants that can tolerate quite a bit of cold weather you can plant them much earlier in the year than other plants that might not handle the cold.

The earliest that you can plant ajuga in Zone 4b 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 ajuga and expect a good harvest is probably August. You probably don't want to wait any later than that or else your ajuga may not have a chance to fully mature. If you are starting your ajuga indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Zone 4b the average date of last frost happens on May 15. It might get as low as -25°F during the coldest months of winter.

Always keep in mind that USDA zone info for Zone 4b is just an average and the actual date of last frost is different every year. Half of the time in Zone 4b there is a last frost after May 15 so just be sure to be ready to protect your ajuga if you have a late frost.

USDA Zone Info for Zone 4b

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Zone 4b

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