One of the first steps you take when you are estimating your gardening schedule is find your 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.

By reviewing the USDA zone info for Watertown it's a good idea to figure out when you can plant periwinkles.

Planting Calendar for Periwinkles

Frost tolerance for periwinkles:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Periwinkles do not do well in cold weather which means that it's important to wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant periwinkles in Watertown 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 grow to maturity. You can get started a couple of weeks earlier by starting your periwinkles indoors.

Last Frost Date

The average date of last frost is April 15 in Watertown. In the coldest months of winter you should expect an average low temperature of -5°F.

Just be sure to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Watertown and it will vary from year to year. Half of the time in Watertown you get a frost after April 15 so just be sure to be ready to protect your periwinkles if you have a surprise late frost.

USDA Zone Info for Watertown

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 Watertown

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