One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of figuring out when it's a good idea to plant pyrethrum is to examine the USDA zone info for Lake Oswego.

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 Lake Oswego is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant pyrethrum and expect a good harvest is probably September. Any later than that and your pyrethrum may not have a chance to fully mature. You can get started a little bit earlier by starting your pyrethrum indoors.

Last Frost Date

The average date of last frost is March 15 in Lake Oswego. It might get as low as 15°F during the coldest months of winter.

Remember that USDA zone info for Lake Oswego is not always accurate and the actual date of last frost is different every year. Half of the time in Lake Oswego you get a frost after March 15 so make sure that you are prepared to protect your pyrethrum in the event of a late frost.

USDA Zone Info for Lake Oswego

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°F

This means that on a really cold year, the coldest it will get is 15°F. On most years you should be prepared to experience lows near 20°F.

Plants to Grow in Lake Oswego

You may be interested in your other planting guides for Lake Oswego.