One of the first steps you take when you are estimating your gardening schedule is find your 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.

The USDA zone info for Zone 4a can be looked at to determine when to plant coral bells.

Planting Calendar for Coral Bells

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

Coral Bells do ok in a little bit of cold which tells us that you can plant them a little earlier in the year than more sensitive plants.

The earliest that you can plant coral bells 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 coral bells and expect a good harvest is probably August. If you wait any later than that and your coral bells may not have a chance to grow to maturity. If you are starting your coral bells indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Zone 4a and it is different every year. Half of the time in Zone 4a you get a frost after May 15 so make sure that you are prepared to cover your coral bells 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.