Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of estimating when to plant trifolium is to examine the USDA zone info for Bismarck.

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 mild cold which tells us that you can plant them a bit earlier in the year than more sensitive plants.

The earliest that you can plant trifolium in Bismarck is April. However, you really should wait until May 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 fully mature. You can get started a few weeks earlier by starting your trifolium indoors.

Last Frost Date

On average the last frost has passed is on May 15 in Bismarck. It might get as low as -30°F during the coldest months of winter.

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Bismarck and it changes from year to year. Half of the time in Bismarck you get surprised by a frost after May 15 so just be sure to be ready to protect your trifolium if you have one of those late frosts.

USDA Zone Info for Bismarck

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Bismarck

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