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 earliest that you can plant osteospermum in Watertown can be determined by reviewing the USDA zone info.

Planting Calendar for Osteospermum

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

Osteospermum are moderately cold tolerant which means that you can plant them earlier than plants that are more sensitive to the cold.

The earliest that you can plant osteospermum 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 osteospermum and expect a good harvest is probably August. If you wait any later than that and your osteospermum may not have a chance to grow to maturity. If you are starting your osteospermum indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost is on May 15 in Watertown. You should expect an average low temperature of -30°F in the coldest months of winter.

Since the USDA zone info for Watertown is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Watertown you get surprised by a frost after May 15 so be sure to be ready to protect your osteospermum in the event of 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.