One of the first steps you take when you are figuring out 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.

A common way of getting a good idea when it's the best time to plant dipladenia is to consult the USDA zone info for Alton.

Planting Calendar for Dipladenia

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

Since dipladenia require warm weather it's necessary to wait until after the last frost before you can plant them.

The earliest that you can plant dipladenia 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 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 grow to maturity. You can get started a few weeks earlier by starting your dipladenia indoors.

Last Frost Date

On average the last frost when the weather gets warmer 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 USDA zone info for Alton may not be accurate from year to year and the actual date of last frost will vary from year to year. Since half of the time in Alton you get a frost after April 15 be ready to cover your dipladenia in the event of a surprise 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.