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.

The USDA zone info for Pierre can be reviewed to determine when it's possible to plant helianthemum.

Planting Calendar for Helianthemum

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

You can plant helianthemum a bit earlier in the year because they do well in moderate cold.

The earliest that you can plant helianthemum in Pierre 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 helianthemum and expect a good harvest is probably August. If you wait any later than that and your helianthemum may not have a chance to fully mature. Starting your helianthemum 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 Pierre. It might get as low as -25°F during the coldest months of winter.

Since the USDA zone info for Pierre is not always accurate the actual date of last frost can change quite a bit from year to year. Half of the time in Pierre it frosts late in the year after May 15 so always be ready to protect your helianthemum if you have one of those late frosts.

USDA Zone Info for Pierre

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 Pierre

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