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.

By looking at the USDA zone info for El Cajon it's a good idea to estimate when it's possible to plant onions.

Planting Calendar for Onions

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

You can plant onions earlier in the year because they are one of those plants that can tolerate quite a bit of cold weather.

The earliest that you can plant onions in El Cajon 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 onions and expect a good harvest is probably October. You probably don't want to wait any later than that or else your onions may not have a chance to fully mature. Starting your onions indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In El Cajon the average date of last frost happens on January 31. In the coldest months of winter you should expect an average low temperature of 30°F.

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 El Cajon and it will vary from year to year. Half of the time in El Cajon it frosts late in the year after January 31 so be sure to be ready to protect your onions if you have a surprise late frost.

USDA Zone Info for El Cajon

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 El Cajon

You may be interested in your other planting guides for El Cajon.