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

The USDA zone info for Douglas should be reffered to in order to figure out when it's the best time to plant pyrethrum.

Planting Calendar for Pyrethrum

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

Since pyrethrum are moderately cold tolerant you can plant them a little bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant pyrethrum in Douglas 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. If you wait any later than that and your pyrethrum may not have a chance to grow to maturity. If you are starting your pyrethrum indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Since the USDA zone info for Douglas is just an average the actual date of last frost is different every year. Half of the time in Douglas it frosts late in the year after May 15 so make sure that you are prepared to cover your pyrethrum if you have a surprise late frost.

USDA Zone Info for Douglas

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 Douglas

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