One of the first steps you take when you are determining your gardening schedule is find your 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.

A common way of getting a good idea when it's the best time to plant nasturtium is to use the USDA zone info for Watertown.

Planting Calendar for Nasturtium

Frost tolerance for nasturtium:	Not tolerant of frost.
When to plant:	After the last frost.

Nasturtium require warm weather which means that you must wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant nasturtium 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 nasturtium and expect a good harvest is probably August. Any later than that and your nasturtium may not have a chance to fully mature. If you are starting your nasturtium indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Since the USDA zone info for Watertown is not always accurate the actual date of last frost changes from year to year. Half of the time in Watertown there is a last frost after May 15 so always be ready to cover your nasturtium if you have 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.