One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In El Mirage you can estimate when it's the best time to plant tree onions by using 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 are barely cold tolerant which tells us that you can plant them slightly earlier than other frost tender plants.

The earliest that you can plant tree onions in El Mirage 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. Any later than that and your tree onions may not have a chance to really do well. Starting your tree onions indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is February 15 in El Mirage. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for El Mirage may not be accurate from year to year the actual date of last frost is different every year. Since half of the time in El Mirage you get a frost after February 15 be ready to cover your tree onions in the event of a late frost.

USDA Zone Info for El Mirage

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 El Mirage

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