One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The first opportunity to plant artichokes in Helena should be estimated by looking at the USDA zone info.

Planting Calendar for Artichokes

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

Since artichokes are moderately cold tolerant you can plant them just a bit earlier in the year than other frost tender plants.

The earliest that you can plant artichokes 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 artichokes and expect a good harvest is probably August. Any later than that and your artichokes may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your artichokes 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 may not be accurate from year to year the actual date of last frost will vary from year to year. Half of the time in Helena you get surprised by a frost after May 15 so just be sure to be ready to cover your artichokes in the event of 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.