One of the first steps you take when you are getting a good idea your gardening schedule is find your 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.

A way of estimating when you can plant trifolium is to check out the USDA zone info for Washington.

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 can survive in very little cold which means that you can plant them a bit earlier in the year than plants that are more sensitive to the cold.

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. If you wait any later than that and your trifolium may not have a chance to fully mature. Starting your trifolium indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Washington. In the coldest months of winter you should expect an average low temperature of -10°F.

Always keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Washington and it changes from year to year. Half of the time in Washington last frost occurs after April 15 so make sure that you are ready to protect your trifolium in the event of a late frost.

USDA Zone Info for Washington

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Washington

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