The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Watertown should be used to estimate when it's possible to plant pennisetum.

Planting Calendar for Pennisetum

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

You can plant pennisetum a bit earlier in the year because they do ok in moderate cold.

The earliest that you can plant pennisetum 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 pennisetum and expect a good harvest is probably August. Any later than that and your pennisetum may not have a chance to fully mature. You can get started a few weeks earlier by starting your pennisetum indoors.

Last Frost Date

On average all chance of frost has passed is on May 15 in Watertown. In the coldest months of winter you should expect an average low temperature of -25°F.

Since the USDA zone info for Watertown may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in Watertown you get surprised by a frost after May 15 be ready to protect your pennisetum in the event of a late frost.

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.