One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of getting a good idea when to plant primula is to examine the USDA zone info for Groton.

Planting Calendar for Primula

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

Since primula are very cold tolerant you can plant them much earlier in the year than other frost tender plants.

The earliest that you can plant primula in Groton is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant primula and expect a good harvest is probably September. You probably don't want to wait any later than that or else your primula may not have a chance to really do well. You can get started a little bit earlier by starting your primula indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Groton. It might get as low as -5°F during the coldest months of winter.

Since the USDA zone info for Groton 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 Groton there is a last frost after April 15 be ready to protect your primula if you have a late frost.

USDA Zone Info for Groton

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Groton

You may be interested in your other planting guides for Groton.