The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's possible to estimate when it's a good idea to plant oxalis by referring to the USDA zone info for Portland.

Planting Calendar for Oxalis

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

Since oxalis do not do well in cold weather it's necessary to wait until after the last frost has passed before you can plant them.

The earliest that you can plant oxalis in Portland 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. Starting your oxalis indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost has passed is on February 15 in Portland. It might get as low as 25°F during the coldest months of winter.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Portland and it is different every year. Half of the time in Portland last frost occurs after February 15 so just be sure to be ready to cover your oxalis if you have a late frost.

USDA Zone Info for Portland

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 Portland

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