One of the best tools that you have as gardeners to help us figure out 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.

It's a good idea to estimate when you can plant hardy hibiscus by referring to the USDA zone info for Watertown.

Planting Calendar for Hardy Hibiscus

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

Hardy Hibiscus are one of those plants that can tolerate quite a bit of cold weather which means that you can get them planted much earlier than more sensitive plants.

The earliest that you can plant hardy hibiscus in Watertown is February. However, you really should wait until March 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 September. Any later than that and your hardy hibiscus may not have a chance to grow to maturity. If you are starting your hardy hibiscus 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 April 15. In the coldest months of winter you can expect an average low temperature of -20°F.

Since the USDA zone info for Watertown is an average the actual date of last frost will vary from year to year. Since half of the time in Watertown you get a frost after April 15 be ready to cover your hardy hibiscus in the event of one of those late frosts.

USDA Zone Info for Watertown

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Watertown

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