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

The USDA zone info for Helena can be looked at to estimate when it's a good idea to plant salpiglossis.

Planting Calendar for Salpiglossis

Frost tolerance for salpiglossis:	Not tolerant of frost.
When to plant:	After the last frost.

You really shouldn't plant salpiglossis until after the last frost because they require warm weather.

The earliest that you can plant salpiglossis 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 salpiglossis and expect a good harvest is probably August. If you wait any later than that and your salpiglossis may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your salpiglossis indoors.

Last Frost Date

In Helena the average date of last frost happens on March 15. It might get as low as 10°F during the coldest months of winter.

Remember that the actual date of last frost may not be accurate from year to year 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 you get surprised by a frost after March 15 be ready to protect your salpiglossis 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.