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

You can estimate when it's a good idea to plant tall phlox in Watertown by checking out the USDA zone info.

Planting Calendar for Tall Phlox

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

Since tall phlox are moderately cold tolerant you can plant them a little bit earlier in the year than more sensitive plants.

The earliest that you can plant tall phlox in Watertown is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant tall phlox and expect a good harvest is probably August. You probably don't want to wait any later than that or else your tall phlox may not have a chance to fully mature. Starting your tall phlox indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Watertown the average date of last frost happens on May 15. It might get as low as -25°F during the coldest months of winter.

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Watertown and it changes from year to year. Half of the time in Watertown there is a last frost after May 15 so make sure that you are ready to cover your tall phlox if you have 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.