The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Helena should be reffered to in order to determine when it's the best time to plant brussels sprouts.

Planting Calendar for Brussels Sprouts

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

You can plant brussels sprouts a little earlier in the year because they are moderately cold tolerant.

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

Last Frost Date

The average date of last frost is May 15 in Helena. It might get as low as -25°F during the coldest months of winter.

Since the USDA zone info for Helena is an average the actual date of last frost changes from year to year. Since half of the time in Helena you get surprised by a frost after May 15 be ready to cover your brussels sprouts if you have a late frost.

USDA Zone Info for Helena

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Helena

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