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.

The USDA zone info for Watertown can be looked at to figure out when it's the best time to plant salpiglossis.

Planting Calendar for Salpiglossis

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

Since salpiglossis do not do well in cold weather you have to wait until after the last frost before you can plant them.

The earliest that you can plant salpiglossis 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 salpiglossis and expect a good harvest is probably August. You probably don't want to wait any later than that or else your salpiglossis may not have a chance to fully mature. If you are starting your salpiglossis indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average all chance of frost has passed is on May 15 in Watertown. It might get as low as -25°F during 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 can change quite a bit from year to year. Since half of the time in Watertown there is a last frost after May 15 be ready to cover your salpiglossis in the event of 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.