One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You will be able to determine when it's a good idea to plant purple bell vines by checking out the USDA zone info for Watertown.

Planting Calendar for Purple Bell Vines

Frost tolerance for purple bell vines:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant purple bell vines slightly earlier in the year because they are one of those plants that can tolerate a tiny bit of cold weather.

The earliest that you can plant purple bell vines 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 purple bell vines and expect a good harvest is probably August. Any later than that and your purple bell vines may not have a chance to fully mature. Starting your purple bell vines indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Watertown. In the coldest months of winter you should expect an average low temperature of -30°F.

Always keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Watertown and it changes from year to year. Half of the time in Watertown last frost occurs after May 15 so just be sure to be ready to cover your purple bell vines in the event of one of those late frosts.

USDA Zone Info for Watertown

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Watertown

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