The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. 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 determining when to plant primroses is to consult the USDA zone info for Hillsboro.

Planting Calendar for Primroses

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

Primroses are very cold tolerant which tells us that you can start planting them much earlier than plants that are more sensitive to the cold.

The earliest that you can plant primroses in Hillsboro 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. Any later than that and your primroses may not have a chance to really do well. You can get started a few weeks earlier by starting your primroses indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Hillsboro. You should expect an average low temperature of -10°F in the coldest months of winter.

Remember that USDA zone info for Hillsboro may not be accurate from year to year and the actual date of last frost will vary from year to year. Half of the time in Hillsboro you get a frost after April 15 so be sure to be ready to protect your primroses in the event of a late frost.

USDA Zone Info for Hillsboro

Here is the info for USDA Zone 6a.

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

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Hillsboro

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