Before planting it is a good idea to find your USDA Zone info to figure out your garden 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 digitalis in Zone 4a should be figured out by referring to the USDA zone info.

Planting Calendar for Digitalis

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

Digitalis do well in moderate cold which tells us that you can get them planted earlier than other frost tender plants.

The earliest that you can plant digitalis in Zone 4a 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 digitalis and expect a good harvest is probably August. Any later than that and your digitalis may not have a chance to fully mature. If you are starting your digitalis indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Remember that USDA zone info for Zone 4a 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 Zone 4a you get surprised by a frost after May 15 be ready to protect your digitalis if you have a late frost.

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.