Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. 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 it's the best time to plant lisianthus.

Planting Calendar for Lisianthus

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

It's a bad idea to plant lisianthus until after the last frost because they do not do well in cold weather.

The earliest that you can plant lisianthus in Watertown is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant lisianthus and expect a good harvest is probably August. If you wait any later than that and your lisianthus may not have a chance to fully mature. If you are starting your lisianthus indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Watertown the average date of last frost happens on May 15. It might get as low as -25°F during the coldest months of winter.

Since the USDA zone info for Watertown is not always accurate the actual date of last frost is different every year. Half of the time in Watertown there is a last frost after May 15 so always be ready to protect your lisianthus in the event of one of those late frosts.

USDA Zone Info for Watertown

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Watertown

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