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.

The best time to plant primula in Baltimore can be determined by reviewing the USDA zone info.

Planting Calendar for Primula

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

Since primula do well in cold you can plant them much earlier in the year than other frost tender plants.

The earliest that you can plant primula in Baltimore 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. Any later than that and your primula may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your primula indoors.

Last Frost Date

The average date of last frost is April 15 in Baltimore. You can expect an average low temperature of 5°F in the coldest months of winter.

Since the USDA zone info for Baltimore is just an average the actual date of last frost will vary from year to year. Since half of the time in Baltimore you get surprised by a frost after April 15 be ready to cover your primula in the event of a surprise late frost.

USDA Zone Info for Baltimore

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 Baltimore

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