The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to determine when you can plant primroses by using the USDA zone info for Corona.

Planting Calendar for Primroses

Frost tolerance for primroses:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since primroses do well in cold you can plant them quite a bit earlier in the year than more sensitive plants.

The earliest that you can plant primroses in Corona 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 primroses and expect a good harvest is probably October. You probably don't want to wait any later than that or else your primroses may not have a chance to fully mature. You can get started a little bit earlier by starting your primroses indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on February 15 in Corona. It might get as low as 25°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Corona is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Corona you get surprised by a frost after February 15 so just be sure to be ready to cover your primroses if you have a surprise late frost.

USDA Zone Info for Corona

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 Corona

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