Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A common way of determining when it's a good idea to plant primula is to look at the USDA zone info for South Portland.

Planting Calendar for Primula

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

Primula are very cold tolerant which tells us that you can start planting them much earlier than other plants that might not handle the cold.

The earliest that you can plant primula in South Portland 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 really do well. If you are starting your primula indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in South Portland. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for South Portland is just an average the actual date of last frost can change quite a bit from year to year. Since half of the time in South Portland last frost occurs after April 15 be ready to cover your primula in the event of a surprise late frost.

USDA Zone Info for South Portland

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 South Portland

You may be interested in your other planting guides for South Portland.