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.

The USDA zone info for Helena should be used to figure out when to plant rhubarb.

Planting Calendar for Rhubarb

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

Rhubarb do well in a little bit of cold which means that you can plant them a bit earlier in the year than other frost tender plants.

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

Last Frost Date

The average date of last frost is May 15 in Helena. You should expect an average low temperature of -25°F in the coldest months of winter.

Always keep in mind that USDA zone info for Helena is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Helena there is a last frost after May 15 so make sure that you are prepared to cover your rhubarb if you have a surprise 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.