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.

You can determine when you can plant pyrethrum in Billings by reviewing the USDA zone info.

Planting Calendar for Pyrethrum

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

Pyrethrum tend to make it in a little bit of cold which tells us that you can plant them a little earlier in the year than more sensitive plants.

The earliest that you can plant pyrethrum in Billings 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 grow to maturity. You can get started a little bit earlier by starting your pyrethrum indoors.

Last Frost Date

On average all chance of frost has passed is on May 15 in Billings. It might get as low as -25°F during the coldest months of winter.

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Billings and it is different every year. Half of the time in Billings last frost occurs after May 15 so make sure that you are ready to cover your pyrethrum in the event of a late frost.

USDA Zone Info for Billings

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 Billings

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