One of the best tools that you have as gardeners to help us estimate your gardening schedule is the 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 tropical hibiscus by looking at the USDA zone info for Alton.

Planting Calendar for Tropical Hibiscus

Frost tolerance for tropical hibiscus:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Tropical Hibiscus require warm weather which means that you have to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant tropical hibiscus 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 tropical hibiscus and expect a good harvest is probably August. You probably don't want to wait any later than that or else your tropical hibiscus may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your tropical hibiscus indoors.

Last Frost Date

The average date of last frost is April 15 in Alton. You should expect an average low temperature of -10°F in the coldest months of winter.

Just be sure to remember that the actual date of last frost is an average because it is based on the USDA zone info for Alton and it changes from year to year. Since half of the time in Alton it frosts late in the year after April 15 be ready to protect your tropical hibiscus in the event of one of those late frosts.

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.