One of the first steps you take when you are determining 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.

A common way of determining when it's the best time to plant tree onions is to examine the USDA zone info for Shafter.

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 tend to make it in some cold which means that you can plant them just a tiny bit earlier in the year than other frost tender plants.

The earliest that you can plant tree onions in Shafter 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 fully mature. You can get started a little bit earlier by starting your tree onions indoors.

Last Frost Date

The average date of last frost is February 15 in Shafter. In the coldest months of winter you should expect an average low temperature of 20°F.

Since the USDA zone info for Shafter is just an average the actual date of last frost will vary from year to year. Half of the time in Shafter you get a frost after February 15 so make sure that you are ready to cover your tree onions if you have a late frost.

USDA Zone Info for Shafter

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Shafter

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