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

The earliest that you can plant plectranthus in Helena should be figured out by looking at the USDA zone info.

Planting Calendar for Plectranthus

Frost tolerance for plectranthus:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Plectranthus are not cold tolerant which tells us that it is necessary to wait until it warms up after all chance of frost has passed before you can plant them.

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

The last month that you can plant plectranthus and expect a good harvest is probably August. You probably don't want to wait any later than that or else your plectranthus may not have a chance to really do well. You can get started a couple of weeks earlier by starting your plectranthus indoors.

Last Frost Date

On average all chance of frost has passed is on May 15 in Helena. It might get as low as -25°F during the coldest months of winter.

Remember that USDA zone info for Helena is not always accurate and the actual date of last frost will vary from year to year. Half of the time in Helena last frost occurs after May 15 so make sure that you are ready to cover your plectranthus 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.