One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of making a decision about when it's possible to plant dipladenia is to consult the USDA zone info for Helena.

Planting Calendar for Dipladenia

Frost tolerance for dipladenia:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

It's probably a bad idea to plant dipladenia until after the last frost when the weather gets warmer because they require warm weather.

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

Last Frost Date

In Helena the average date of last frost happens on March 15. You can expect an average low temperature of 10°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Helena is just an average and the actual date of last frost will vary from year to year. Half of the time in Helena there is a last frost after March 15 so be sure to be ready to protect your dipladenia in the event of one of those late frosts.

USDA Zone Info for Helena

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Helena

You may be interested in your other planting guides for Helena.