One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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.

One way of figuring out when it's the best time to plant primula is to examine the USDA zone info for Walden.

Planting Calendar for Primula

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

Primula do well in cold which tells us that you can get them planted much earlier than plants that are more sensitive to the cold.

The earliest that you can plant primula in Walden 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. 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 couple of weeks earlier.

Last Frost Date

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

Keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Walden and it can change quite a bit from year to year. Half of the time in Walden last frost occurs after April 15 so make sure that you are prepared to protect your primula in the event of a surprise late frost.

USDA Zone Info for Walden

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Walden

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