One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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 first opportunity to plant schizanthus in Zone 4a can be estimated by referring to the USDA zone info.

Planting Calendar for Schizanthus

Frost tolerance for schizanthus:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Schizanthus are not cold tolerant which tells us that you have to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant schizanthus in Zone 4a is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant schizanthus and expect a good harvest is probably August. You probably don't want to wait any later than that or else your schizanthus may not have a chance to really do well. You can get started a couple of weeks earlier by starting your schizanthus indoors.

Last Frost Date

In Zone 4a the average date of last frost happens on May 15. It might get as low as -30°F during the coldest months of winter.

It's important to remember that the actual date of last frost is an average because it is based on the USDA zone info for Zone 4a and it changes from year to year. Half of the time in Zone 4a you get a frost after May 15 so make sure that you are prepared to protect your schizanthus 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.