Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Watertown should be reffered to in order to determine when it's the best time to plant primula.

Planting Calendar for Primula

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

You can plant primula earlier in the year because they are one of those plants that can tolerate quite a bit of cold weather.

The earliest that you can plant primula 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 primula and expect a good harvest is probably August. If you wait any later than that and your primula may not have a chance to fully mature. Starting your primula indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average all chance of frost has passed is on May 15 in Watertown. In the coldest months of winter you should expect an average low temperature of -25°F.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Watertown and it is different every year. Since half of the time in Watertown last frost occurs after May 15 be ready to cover your primula if you have 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.