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.

You will be able to figure out when to plant four o' clock by looking at the USDA zone info for Irvine.

Planting Calendar for Four O' Clock

Frost tolerance for four o' clock:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

It's a bad idea to plant four o' clock until after all chance of frost has passed because they are not cold tolerant.

The earliest that you can plant four o' clock in Irvine 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 four o' clock and expect a good harvest is probably September. Any later than that and your four o' clock may not have a chance to grow to maturity. If you are starting your four o' clock indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Irvine the average date of last frost happens on January 31. It might get as low as 30°F during the coldest months of winter.

Since the USDA zone info for Irvine is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Irvine there is a last frost after January 31 so be sure to be ready to cover your four o' clock in the event of one of those late frosts.

USDA Zone Info for Irvine

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 Irvine

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