frostdate name logo in white
frostdate name logo in white

When to Plant Pyrethrum in Mercer Island, WA

One of the first steps you take when you are estimating 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.

By looking at the USDA zone info for Mercer Island it's a good idea to figure out when it's a good idea 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.

Pyrethrum do well in moderate cold which means that you can plant them earlier than more sensitive plants.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant pyrethrum
Possibly ok, but a risky time to plant pyrethrum
Probably not a good time to plant pyrethrum

The earliest that you can plant pyrethrum in Mercer Island 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. You probably don't want to wait any later than that or else your pyrethrum may not have a chance to fully mature. If you are starting your pyrethrum indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on March 15 in Mercer Island. In the coldest months of winter you should expect an average low temperature of 15°F.

Always keep in mind that USDA zone info for Mercer Island may not be accurate from year to year and the actual date of last frost is different every year. Half of the time in Mercer Island it frosts late in the year after March 15 so make sure that you are prepared to protect your pyrethrum in the event of a surprise late frost.

USDA Zone Info for Mercer Island

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 Low15°F
Highest Expected Low20°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 Mercer Island

You may be interested in your other planting guides for Mercer Island.