Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of determining when it's the best time to plant oxalis is to look at the USDA zone info for Sonoma.

Planting Calendar for Oxalis

Frost tolerance for oxalis:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Oxalis are not cold tolerant which means that it's important to wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant oxalis in Sonoma is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant oxalis and expect a good harvest is probably September. You probably don't want to wait any later than that or else your oxalis may not have a chance to grow to maturity. If you are starting your oxalis indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on February 15 in Sonoma. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for Sonoma may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in Sonoma you get a frost after February 15 be ready to cover your oxalis if you have one of those late frosts.

USDA Zone Info for Sonoma

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 Sonoma

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