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.

One way of getting a good idea when it's the best time to plant celeriac is to consult the USDA zone info for Helena.

Planting Calendar for Celeriac

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

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

The earliest that you can plant celeriac 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 celeriac and expect a good harvest is probably August. If you wait any later than that and your celeriac may not have a chance to really do well. Starting your celeriac indoors is a great way to get them started a little bit earlier.

Last Frost Date

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

Just be sure to remember that USDA zone info for Helena is an average and the actual date of last frost is different every year. Half of the time in Helena there is a last frost after May 15 so just be sure to be ready to cover your celeriac 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.