One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant tree onions in El Cajon can be determined by referring to the USDA zone info.

Planting Calendar for Tree onions

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

Tree onions do ok in some cold which means that you can plant them slightly earlier in the year than more sensitive plants.

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

Last Frost Date

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

Remember that USDA zone info for El Cajon may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Half of the time in El Cajon you get surprised by a frost after January 31 so make sure that you are ready to protect your tree onions in the event of 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.