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.

By using the USDA zone info for Lake Oswego it's possible to figure out when it's a good idea to plant rosemary.

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 plants that might not handle the cold.

The earliest that you can plant rosemary in Lake Oswego 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. Any later than that and your rosemary may not have a chance to fully mature. If you are starting your rosemary indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost is on March 15 in Lake Oswego. In the coldest months of winter you can expect an average low temperature of 15°F.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Lake Oswego and it changes from year to year. Half of the time in Lake Oswego there is a last frost after March 15 so make sure that you are ready to protect your rosemary if you have a surprise late frost.

USDA Zone Info for Lake Oswego

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 Lake Oswego

You may be interested in your other planting guides for Lake Oswego.