One of the first steps you take when you are making a decision about your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of figuring out when it's possible to plant trifolium is to refer to the USDA zone info for Zone 1a.

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 tend to make it in some cold which means that you can plant them a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant trifolium in Zone 1a is June. However, you really should wait until July if you don't want to take any chances.

The last month that you can plant trifolium and expect a good harvest is probably July. You probably don't want to wait any later than that or else your trifolium may not have a chance to fully mature. If you are starting your trifolium indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost is on June 15 in Zone 1a. You can expect an average low temperature of -60°F in the coldest months of winter.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Zone 1a and it changes from year to year. Since half of the time in Zone 1a you get a frost after June 15 be ready to cover your trifolium in the event of a surprise late frost.

USDA Zone Info for Zone 1a

Here is the info for USDA Zone 1a.

Average Date of Last Frost (spring)	June 15
Average Date of First Frost (fall)	July 15
Lowest Expected Low	-60°F
Highest Expected Low	-55°F

This means that on a really cold year, the coldest it will get is -60°F. On most years you should be prepared to experience lows near -55°F.

Plants to Grow in Zone 1a

You may be interested in your other planting guides for Zone 1a.