Before planting it is a good idea to find your USDA Zone info to figure out your garden 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 estimate when it's the best time to plant zinnia by looking at the USDA zone info.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Zinnia require warm weather which tells us that you need to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant zinnia 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 zinnia and expect a good harvest is probably August. You probably don't want to wait any later than that or else your zinnia may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your zinnia indoors.

Last Frost Date

In Watertown the average date of last frost happens on May 15. You can expect an average low temperature of -30°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. Since half of the time in Watertown it frosts late in the year after May 15 be ready to protect your zinnia 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.