Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By using the USDA zone info for Zone 4a you should be able to determine when it's the best time to plant iberis.

Planting Calendar for Iberis

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

Iberis can survive in a little bit of cold which tells us that you can plant them a bit earlier in the year than more sensitive plants.

The earliest that you can plant iberis 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 iberis and expect a good harvest is probably August. You probably don't want to wait any later than that or else your iberis may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your iberis indoors.

Last Frost Date

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

Since the USDA zone info for Zone 4a may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Zone 4a there is a last frost after May 15 so make sure that you are prepared to protect your iberis if you have a surprise 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.