The USDA Zone info is a great tool for gardeners to help us estimate 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.

You can figure out when it's a good idea to plant trifolium in Washington by using the USDA zone info.

Planting Calendar for Trifolium

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

Trifolium do ok in a tiny bit of cold which means that you can plant them just a tiny bit earlier in the year than other frost tender plants.

The earliest that you can plant trifolium in Washington 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 trifolium and expect a good harvest is probably August. You probably don't want to wait any later than that or else your trifolium may not have a chance to really do well. You can get started a couple of weeks earlier by starting your trifolium indoors.

Last Frost Date

The average date of last frost is April 15 in Washington. It might get as low as -5°F during the coldest months of winter.

Since the USDA zone info for Washington is an average the actual date of last frost changes from year to year. Since half of the time in Washington you get a frost after April 15 be ready to cover your trifolium if you have a late frost.

USDA Zone Info for Washington

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Washington

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