The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By using the USDA zone info for Portland you should be able to estimate when it's the best time to plant oxalis.

Planting Calendar for Oxalis

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

It's probably not a good idea to plant oxalis until after the last frost has passed because they are not cold tolerant.

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

The last month that you can plant oxalis and expect a good harvest is probably August. Any later than that and your oxalis may not have a chance to fully mature. You can get started a few weeks earlier by starting your oxalis indoors.

Last Frost Date

The average date of last frost is March 15 in Portland. It might get as low as 15°F during the coldest months of winter.

Since the USDA zone info for Portland is not always accurate the actual date of last frost is different every year. Since half of the time in Portland you get a frost after March 15 be ready to protect your oxalis in the event of a surprise late frost.

USDA Zone Info for Portland

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°F

This means that on a really cold year, the coldest it will get is 15°F. On most years you should be prepared to experience lows near 20°F.

Plants to Grow in Portland

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