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.

The USDA zone info for Presidio can be reffered to in order to determine when to plant tree onions.

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 well in mild cold which tells us that you can plant them a bit earlier in the year than more sensitive plants.

The earliest that you can plant tree onions in Presidio 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 grow to maturity. 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 Presidio. It might get as low as 20°F during the coldest months of winter.

Since the USDA zone info for Presidio is just an average the actual date of last frost will vary from year to year. Since half of the time in Presidio last frost occurs after February 15 be ready to protect your tree onions if you have a surprise late frost.

USDA Zone Info for Presidio

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 Presidio

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