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.

By using the USDA zone info for Helena it's a good idea to figure out when it's possible to plant jerusalem artichokes.

Planting Calendar for Jerusalem artichokes

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

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

The earliest that you can plant jerusalem artichokes in Helena is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant jerusalem artichokes and expect a good harvest is probably September. If you wait any later than that and your jerusalem artichokes may not have a chance to really do well. You can get started a couple of weeks earlier by starting your jerusalem artichokes indoors.

Last Frost Date

The average date of last frost is March 15 in Helena. You can expect an average low temperature of 10°F in the coldest months of winter.

Just be sure to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Helena and it is different every year. Half of the time in Helena last frost occurs after March 15 so just be sure to be ready to protect your jerusalem artichokes in the event of a late frost.

USDA Zone Info for Helena

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Helena

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