One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By using the USDA zone info for Helena it's possible to estimate when it's the best time to plant carnation.

Planting Calendar for Carnation

Frost tolerance for carnation:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since carnation do well in cold you can plant them quite a bit earlier in the year than other frost tender plants.

The earliest that you can plant carnation 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 carnation and expect a good harvest is probably August. If you wait any later than that and your carnation may not have a chance to grow to maturity. If you are starting your carnation indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Always keep in mind that USDA zone info for Helena may not be accurate from year to year and the actual date of last frost changes from year to year. Half of the time in Helena you get surprised by a frost after May 15 so make sure that you are prepared to protect your carnation 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.