One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The best time to plant periwinkles in Keene can be estimated by referring to 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.

Periwinkles do not do well in cold weather which tells us that you must wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant periwinkles in Keene 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. You can get started a little bit earlier by starting your periwinkles indoors.

Last Frost Date

In Keene the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -15°F.

It's important to remember that the actual date of last frost is an average because it is based on the USDA zone info for Keene and it can change quite a bit from year to year. Half of the time in Keene you get surprised by a frost after April 15 so be sure to be ready to protect your periwinkles in the event of a late frost.

USDA Zone Info for Keene

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 Keene

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