One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first opportunity to plant tree onions in Berkeley can be estimated by looking at 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.

You can plant tree onions slightly earlier in the year because they do ok in moderate cold.

The earliest that you can plant tree onions in Berkeley 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. If you are starting your tree onions indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

The average date of last frost is January 31 in Berkeley. You can expect an average low temperature of 30°F in the coldest months of winter.

Remember that USDA zone info for Berkeley is just an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Berkeley you get surprised by a frost after January 31 be ready to cover your tree onions if you have a surprise late frost.

USDA Zone Info for Berkeley

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 Berkeley

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