The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Watertown you can figure out when it's the best time to plant hardy hibiscus by using the USDA zone info.

Planting Calendar for Hardy Hibiscus

Frost tolerance for hardy hibiscus:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since hardy hibiscus do well in cold you can plant them earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant hardy hibiscus in Watertown is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant hardy hibiscus and expect a good harvest is probably August. If you wait any later than that and your hardy hibiscus may not have a chance to really do well. Starting your hardy hibiscus 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.

Since the USDA zone info for Watertown is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Watertown it frosts late in the year after May 15 so make sure that you are prepared to cover your hardy hibiscus if you have a late frost.

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.