One of the best tools that you have as gardeners to help us determine 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 USDA zone info for Portland can be read to estimate when to plant bittercress.

Planting Calendar for Bittercress

Frost tolerance for bittercress:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Since bittercress are one of those plants that can tolerate a tiny bit of cold weather you can plant them slightly earlier in the year than other frost tender plants.

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

Last Frost Date

On average the last frost when the weather gets warmer is on February 15 in Portland. In the coldest months of winter you can expect an average low temperature of 25°F.

Since the USDA zone info for Portland is just an average the actual date of last frost is different every year. Half of the time in Portland last frost occurs after February 15 so always be ready to protect your bittercress if you have one of those late frosts.

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.