Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. 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 figuring out when it's a good idea to plant bok choi is to refer to the USDA zone info for Havre.

Planting Calendar for Bok Choi

Frost tolerance for bok choi:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Bok Choi can survive in moderate cold which tells us that you can plant them a little earlier in the year than other plants that might not handle the cold.

The earliest that you can plant bok choi in Havre 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 bok choi and expect a good harvest is probably August. You probably don't want to wait any later than that or else your bok choi may not have a chance to fully mature. You can get started a few weeks earlier by starting your bok choi indoors.

Last Frost Date

On average the last frost is on May 15 in Havre. You can expect an average low temperature of -30°F in the coldest months of winter.

It's important to remember that the actual date of last frost is an average because it is based on the USDA zone info for Havre and it can change quite a bit from year to year. Half of the time in Havre you get surprised by a frost after May 15 so just be sure to be ready to protect your bok choi in the event of one of those late frosts.

USDA Zone Info for Havre

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 Havre

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