One of the first steps you take when you are figuring out your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first opportunity to plant oxalis in Helena should be figured out by reviewing the USDA zone info.

Planting Calendar for Oxalis

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

Since oxalis require warm weather it is necessary to wait until after the last frost has passed before you can plant them.

The earliest that you can plant oxalis in Helena 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. If you wait any later than that and your oxalis may not have a chance to fully mature. Starting your oxalis indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average all chance of frost has passed is on May 15 in Helena. In the coldest months of winter you can expect an average low temperature of -25°F.

Just be sure to remember that USDA zone info for Helena is an average and the actual date of last frost is different every year. Since half of the time in Helena last frost occurs after May 15 be ready to cover your oxalis in the event of a late frost.

USDA Zone Info for Helena

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 Helena

You may be interested in your other planting guides for Helena.