The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By referring to the USDA zone info for Helena it's a good idea to figure out when you can plant sweet peas.

Planting Calendar for Sweet Peas

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

Since sweet peas do ok in moderate cold you can plant them just a tiny bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant sweet peas 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 sweet peas and expect a good harvest is probably August. Any later than that and your sweet peas may not have a chance to really do well. If you are starting your sweet peas indoors then you might be able to get away with starting them a few weeks 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.

Since the USDA zone info for Helena may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Since half of the time in Helena it frosts late in the year after May 15 be ready to cover your sweet peas if you have one of those late frosts.

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.