One of the first steps you take when you are determining 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.

You should be able to determine when it's the best time to plant diascia by reviewing the USDA zone info for Alton.

Planting Calendar for Diascia

Frost tolerance for diascia:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Since diascia do well in moderate cold you can plant them just a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant diascia in Alton is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant diascia and expect a good harvest is probably September. You probably don't want to wait any later than that or else your diascia may not have a chance to fully mature. If you are starting your diascia indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Alton. You should expect an average low temperature of -10°F in the coldest months of winter.

Since the USDA zone info for Alton may not be accurate from year to year the actual date of last frost changes from year to year. Half of the time in Alton it frosts late in the year after April 15 so just be sure to be ready to protect your diascia 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.