The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's possible to figure out when it's possible to plant lobelia by looking at the USDA zone info for Watertown.

Planting Calendar for Lobelia

Frost tolerance for lobelia:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Lobelia are very cold tolerant which tells us that you can get them planted much earlier than more sensitive plants.

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

Last Frost Date

The average date of last frost is May 15 in Watertown. You should expect an average low temperature of -25°F in the coldest months of winter.

Since the USDA zone info for Watertown may not be accurate from year to year the actual date of last frost will vary from year to year. Since half of the time in Watertown there is a last frost after May 15 be ready to cover your lobelia 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.