One of the best tools that you have as gardeners to help us estimate 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 best time to plant pyrethrum in Portola Valley should be estimated by checking out 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 do ok in mild cold which tells us that you can plant them just a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant pyrethrum in Portola Valley is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant pyrethrum and expect a good harvest is probably October. You probably don't want to wait any later than that or else your pyrethrum may not have a chance to really do well. You can get started a few weeks earlier by starting your pyrethrum indoors.

Last Frost Date

On average all chance of frost has passed is on January 31 in Portola Valley. You can expect an average low temperature of 30°F in the coldest months of winter.

It's important to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Portola Valley and it can change quite a bit from year to year. Half of the time in Portola Valley you get surprised by a frost after January 31 so be sure to be ready to protect your pyrethrum if you have a late frost.

USDA Zone Info for Portola Valley

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in Portola Valley

You may be interested in your other planting guides for Portola Valley.