One of the best tools that you have as gardeners to help us determine 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.

The earliest that you can plant periwinkles in Souderton should 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.

It's probably not a good idea to plant periwinkles until after all chance of frost has passed because they are not cold tolerant.

The earliest that you can plant periwinkles in Souderton 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. If you wait any later than that and your periwinkles may not have a chance to fully mature. You can get started a few weeks earlier by starting your periwinkles indoors.

Last Frost Date

On average the last frost has passed is on April 15 in Souderton. In the coldest months of winter you can expect an average low temperature of -5°F.

Since the USDA zone info for Souderton is an average the actual date of last frost will vary from year to year. Half of the time in Souderton there is a last frost after April 15 so make sure that you are prepared to cover your periwinkles if you have a late frost.

USDA Zone Info for Souderton

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Souderton

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