One of the first steps you take when you are estimating your gardening schedule is find your 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 chervil in Helena should be figured out by looking at the USDA zone info.

Planting Calendar for Chervil

Frost tolerance for chervil:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Chervil do ok in moderate cold which means that you can start planting them slightly earlier than other plants that might not handle the cold.

The earliest that you can plant chervil in Helena is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant chervil and expect a good harvest is probably August. You probably don't want to wait any later than that or else your chervil may not have a chance to grow to maturity. If you are starting your chervil indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Helena. You should expect an average low temperature of -25°F in the coldest months of winter.

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 can change quite a bit from year to year. Since half of the time in Helena there is a last frost after May 15 be ready to cover your chervil 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.