Before planting it is a good idea to find your USDA Zone info to determine 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 way of determining when it's a good idea to plant rosemary is to use the USDA zone info for Hillsboro.

Planting Calendar for Rosemary

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

Rosemary do ok in pretty solid cold which means that you can plant them much earlier in the year than other frost tender plants.

The earliest that you can plant rosemary 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 rosemary and expect a good harvest is probably September. You probably don't want to wait any later than that or else your rosemary may not have a chance to really do well. If you are starting your rosemary indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Hillsboro the average date of last frost happens on March 15. In the coldest months of winter you can expect an average low temperature of 10°F.

Keep in mind that the actual date of last frost is not always accurate because it is based on the USDA zone info for Hillsboro and it can change quite a bit from year to year. Half of the time in Hillsboro it frosts late in the year after March 15 so always be ready to protect your rosemary in the event of a late frost.

USDA Zone Info for Hillsboro

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°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 15°F.

Plants to Grow in Hillsboro

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