One of the first steps you take when you are figuring out 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 best time to plant achimenes in Zone 4b should be determined by reviewing the USDA zone info.

Planting Calendar for Achimenes

Frost tolerance for achimenes:	Not tolerant of frost.
When to plant:	After the last frost.

Achimenes require warm weather which tells us that you really should wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant achimenes in Zone 4b 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 achimenes and expect a good harvest is probably August. You probably don't want to wait any later than that or else your achimenes may not have a chance to fully mature. If you are starting your achimenes indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost has passed is on May 15 in Zone 4b. It might get as low as -25°F during the coldest months of winter.

Keep in mind that USDA zone info for Zone 4b is an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Zone 4b you get a frost after May 15 be ready to protect your achimenes in the event of one of those late frosts.

USDA Zone Info for Zone 4b

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Zone 4b

You may be interested in your other planting guides for Zone 4b.