One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By using the USDA zone info for Durham you should be able to estimate when you can plant primula.

Planting Calendar for Primula

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

Primula tend to make it in pretty solid cold which means that you can plant them a lot earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant primula in Durham 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 fully mature. You can get started a little bit earlier by starting your primula indoors.

Last Frost Date

The average date of last frost is April 15 in Durham. It might get as low as 5°F during the coldest months of winter.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Durham and it changes from year to year. Since half of the time in Durham there is a last frost after April 15 be ready to protect your primula in the event of a late frost.

USDA Zone Info for Durham

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°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 10°F.

Plants to Grow in Durham

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