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.

It's possible to determine when it's a good idea to plant violas by looking at the USDA zone info for Zone 4b.

Planting Calendar for Violas

Frost tolerance for violas:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Violas are one of those plants that can tolerate quite a bit of cold weather which tells us that you can plant them a quite a bit earlier than other frost tender plants.

The earliest that you can plant violas in Zone 4b 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 violas and expect a good harvest is probably August. Any later than that and your violas may not have a chance to really do well. If you are starting your violas indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Since the USDA zone info for Zone 4b is an average the actual date of last frost changes from year to year. Half of the time in Zone 4b it frosts late in the year after May 15 so always be ready to cover your violas in the event of a late frost.

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.