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

The earliest that you can plant periwinkles in Normal can be estimated by reviewing the USDA zone info.

Planting Calendar for Periwinkles

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

You should not plant periwinkles until after the last frost because they are not cold tolerant.

The earliest that you can plant periwinkles in Normal 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 periwinkles and expect a good harvest is probably August. Any later than that and your periwinkles may not have a chance to grow to maturity. Starting your periwinkles indoors is a great way to get them started a few weeks earlier.

Last Frost Date

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

Remember that USDA zone info for Normal is not always accurate and the actual date of last frost changes from year to year. Half of the time in Normal there is a last frost after April 15 so make sure that you are prepared to cover your periwinkles if you have a surprise late frost.

USDA Zone Info for Normal

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Normal

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