One of the first steps you take when you are getting a good idea 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.

A way of figuring out when it's possible to plant chrysanthemums is to examine the USDA zone info for Helena.

Planting Calendar for Chrysanthemums

Frost tolerance for chrysanthemums:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant chrysanthemums just a tiny bit earlier in the year because they are one of those plants that can tolerate a tiny bit of cold weather.

The earliest that you can plant chrysanthemums in Helena is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant chrysanthemums and expect a good harvest is probably August. You probably don't want to wait any later than that or else your chrysanthemums may not have a chance to fully mature. Starting your chrysanthemums indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Helena the average date of last frost happens on May 15. In the coldest months of winter you should expect an average low temperature of -25°F.

Remember that USDA zone info for Helena is not always accurate and the actual date of last frost changes from year to year. Half of the time in Helena there is a last frost after May 15 so make sure that you are ready to cover your chrysanthemums in the event of one of those late frosts.

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.