One of the best tools that you have as gardeners to help us estimate 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 Gresham it's a good idea to determine when you can plant primroses.

Planting Calendar for Primroses

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

Primroses can survive in cold weather 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 primroses in Gresham 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 primroses and expect a good harvest is probably September. You probably don't want to wait any later than that or else your primroses may not have a chance to grow to maturity. If you are starting your primroses indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Gresham the average date of last frost happens on March 15. In the coldest months of winter you can expect an average low temperature of 15°F.

Since the USDA zone info for Gresham is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Gresham last frost occurs after March 15 be ready to protect your primroses in the event of a surprise late frost.

USDA Zone Info for Gresham

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°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 20°F.

Plants to Grow in Gresham

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