The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant pyrethrum in Riverside should be estimated by using 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 means that you can plant them a little earlier in the year than more sensitive plants.

The earliest that you can plant pyrethrum in Riverside 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. Any later than that and 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

The average date of last frost is February 15 in Riverside. It might get as low as 25°F during the coldest months of winter.

Always keep in mind that USDA zone info for Riverside may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Half of the time in Riverside last frost occurs after February 15 so make sure that you are ready to cover your pyrethrum in the event of one of those late frosts.

USDA Zone Info for Riverside

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°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 30°F.

Plants to Grow in Riverside

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