One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's possible to estimate when it's the best time to plant phlox by referring to the USDA zone info for Watertown.

Planting Calendar for Phlox

Frost tolerance for phlox:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Phlox do well in moderate cold which tells us that you can plant them earlier than more sensitive plants.

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

Last Frost Date

The average date of last frost is April 15 in Watertown. You can expect an average low temperature of -20°F in the coldest months of winter.

Since the USDA zone info for Watertown is not always accurate the actual date of last frost can change quite a bit from year to year. Since half of the time in Watertown there is a last frost after April 15 be ready to protect your phlox 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.