The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can figure out when to plant trifolium in Walla Walla by reviewing 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.

Since trifolium are barely cold tolerant you can plant them slightly earlier in the year than other frost tender plants.

The earliest that you can plant trifolium in Walla Walla 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. Any later than that and your trifolium may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your trifolium indoors.

Last Frost Date

On average the last frost is on April 15 in Walla Walla. You should expect an average low temperature of 0°F in the coldest months of winter.

Always keep in mind that USDA zone info for Walla Walla is an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Walla Walla there is a last frost after April 15 be ready to protect your trifolium if you have one of those late frosts.

USDA Zone Info for Walla Walla

Here is the info for USDA Zone 7a.

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

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

Plants to Grow in Walla Walla

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