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.

You should be able to estimate when you can plant arabis by reviewing the USDA zone info for Portland.

Planting Calendar for Arabis

Frost tolerance for arabis:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Arabis are very cold tolerant which means that you can plant them a quite a bit earlier than other plants that might not handle the cold.

The earliest that you can plant arabis in Portland 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 arabis and expect a good harvest is probably September. If you wait any later than that and your arabis may not have a chance to grow to maturity. If you are starting your arabis indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Portland. In the coldest months of winter you should expect an average low temperature of -15°F.

Keep in mind that USDA zone info for Portland is not always accurate and the actual date of last frost will vary from year to year. Since half of the time in Portland you get a frost after April 15 be ready to cover your arabis if you have one of those late frosts.

USDA Zone Info for Portland

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°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 -10°F.

Plants to Grow in Portland

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