One of the first steps you take when you are figuring out 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.

In Riverside you can determine when it's the best time to plant calliopsis by referring to the USDA zone info.

Planting Calendar for Calliopsis

Frost tolerance for calliopsis:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Calliopsis do not do well in cold weather which means that you need to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant calliopsis in Riverside is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant calliopsis and expect a good harvest is probably September. If you wait any later than that and your calliopsis may not have a chance to grow to maturity. You can get started a little bit earlier by starting your calliopsis indoors.

Last Frost Date

On average the last frost has passed is on February 15 in Riverside. It might get as low as 25°F during the coldest months of winter.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Riverside and it is different every year. Half of the time in Riverside there is a last frost after February 15 so just be sure to be ready to cover your calliopsis in the event of a surprise late frost.

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.