One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can figure out when it's a good idea to plant pearl onions in Costa Mesa by looking at the USDA zone info.

Planting Calendar for Pearl onions

Frost tolerance for pearl onions:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since pearl onions are barely cold tolerant you can plant them just a tiny bit earlier in the year than more sensitive plants.

The earliest that you can plant pearl onions in Costa Mesa 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 pearl onions and expect a good harvest is probably September. You probably don't want to wait any later than that or else your pearl onions may not have a chance to really do well. Starting your pearl onions indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on January 31 in Costa Mesa. In the coldest months of winter you should expect an average low temperature of 35°F.

Since the USDA zone info for Costa Mesa may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in Costa Mesa it frosts late in the year after January 31 be ready to cover your pearl onions if you have a late frost.

USDA Zone Info for Costa Mesa

Here is the info for USDA Zone 10b.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	35°F
Highest Expected Low	40°F

This means that on a really cold year, the coldest it will get is 35°F. On most years you should be prepared to experience lows near 40°F.

Plants to Grow in Costa Mesa

You may be interested in your other planting guides for Costa Mesa.