Before planting it is a good idea to find your USDA Zone info to figure out 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.

In Riverside you can estimate when it's the best time to plant pyrethrum by referring to 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.

You can plant pyrethrum just a bit earlier in the year because they are one of those plants that can tolerate a little bit of cold weather.

The earliest that you can plant pyrethrum in Riverside 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 really do well. If you are starting your pyrethrum indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Riverside the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -10°F.

Remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Riverside and it changes from year to year. Half of the time in Riverside last frost occurs after April 15 so be sure to be ready to protect your pyrethrum if you have a late frost.

USDA Zone Info for Riverside

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Riverside

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