One of the best tools that you have as gardeners to help us estimate 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.

You can estimate when you can plant mimulus in Zone 4b by referring to the USDA zone info.

Planting Calendar for Mimulus

Frost tolerance for mimulus:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

It's not a good idea to plant mimulus until after the last frost because they do not do well in cold weather.

The earliest that you can plant mimulus 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 mimulus and expect a good harvest is probably August. Any later than that and your mimulus may not have a chance to fully mature. Starting your mimulus indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Zone 4b. In the coldest months of winter you should expect an average low temperature of -25°F.

Always keep in mind that USDA zone info for Zone 4b is just an average and the actual date of last frost is different every year. Half of the time in Zone 4b you get a frost after May 15 so be sure to be ready to protect your mimulus 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.