One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Seattle can be used to figure out when it's the best time 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 barely cold tolerant you can plant them slightly earlier in the year than more sensitive plants.

The earliest that you can plant bittercress in Seattle 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 bittercress and expect a good harvest is probably August. You probably don't want to wait any later than that or else your bittercress may not have a chance to grow to maturity. You can get started a little bit earlier by starting your bittercress indoors.

Last Frost Date

In Seattle the average date of last frost happens on March 15. It might get as low as 15°F during the coldest months of winter.

Since the USDA zone info for Seattle may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Seattle it frosts late in the year after March 15 so make sure that you are ready to cover your bittercress if you have a surprise late frost.

USDA Zone Info for Seattle

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 Seattle

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