Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

One way of determining when it's a good idea to plant pyrethrum is to look at the USDA zone info for Holmen.

Planting Calendar for Pyrethrum

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

Since pyrethrum do well in moderate cold you can plant them a little earlier in the year than other frost tender plants.

The earliest that you can plant pyrethrum in Holmen 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 pyrethrum and expect a good harvest is probably August. Any later than that and your pyrethrum may not have a chance to really do well. Starting your pyrethrum indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Holmen. In the coldest months of winter you should expect an average low temperature of -25°F.

Since the USDA zone info for Holmen is just an average the actual date of last frost is different every year. Half of the time in Holmen there is a last frost after May 15 so be sure to be ready to cover your pyrethrum in the event of one of those late frosts.

USDA Zone Info for Holmen

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 Holmen

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