The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By referring to the USDA zone info for Zone 4b it's a good idea to estimate when you can plant oxalis.

Planting Calendar for Oxalis

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

You should not plant oxalis until after the last frost because they are not cold tolerant.

The earliest that you can plant oxalis 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 oxalis and expect a good harvest is probably August. Any later than that and your oxalis may not have a chance to really do well. You can get started a couple of weeks earlier by starting your oxalis indoors.

Last Frost Date

On average all chance of frost has passed is on May 15 in Zone 4b. You can expect an average low temperature of -25°F in the coldest months of winter.

Since the USDA zone info for Zone 4b is just an average the actual date of last frost will vary from year to year. Half of the time in Zone 4b you get surprised by a frost after May 15 so make sure that you are ready to protect your oxalis if you have a surprise 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.