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

A way of determining when it's a good idea to plant hemerocallis is to examine the USDA zone info for Helena.

Planting Calendar for Hemerocallis

Frost tolerance for hemerocallis:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Hemerocallis do ok in mild cold which means that you can plant them a little bit earlier in the year than other frost tender plants.

The earliest that you can plant hemerocallis in Helena 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 hemerocallis and expect a good harvest is probably August. Any later than that and your hemerocallis may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your hemerocallis indoors.

Last Frost Date

The average date of last frost is May 15 in Helena. 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 Helena may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Since half of the time in Helena there is a last frost after May 15 be ready to protect your hemerocallis if you have a surprise 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.