Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By looking at the USDA zone info for Alton you should be able to determine 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.

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

The earliest that you can plant salpiglossis in Alton 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. You probably don't want to wait any later than that or else your salpiglossis may not have a chance to fully mature. If you are starting your salpiglossis indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost is on April 15 in Alton. It might get as low as -10°F during the coldest months of winter.

It's important to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Alton and it is different every year. Half of the time in Alton there is a last frost after April 15 so just be sure to be ready to protect your salpiglossis in the event of a late frost.

USDA Zone Info for Alton

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°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 -5°F.

Plants to Grow in Alton

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