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.

You should be able to estimate when to plant erysimum by referring to the USDA zone info for Zone 4a.

Planting Calendar for Erysimum

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

You can plant erysimum a little earlier in the year because they are one of those plants that can tolerate a little bit of cold weather.

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

Last Frost Date

In Zone 4a the average date of last frost happens on May 15. 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 will vary from year to year. Half of the time in Zone 4a last frost occurs after May 15 so make sure that you are prepared to protect your erysimum in the event of 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.