One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The USDA zone info for Portland should be reviewed to determine when it's possible to plant lemon balm.

Planting Calendar for Lemon balm

Frost tolerance for lemon balm:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Lemon balm do ok in moderate cold which tells us that you can start planting them slightly earlier than other plants that might not handle the cold.

The earliest that you can plant lemon balm in Portland is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant lemon balm and expect a good harvest is probably August. You probably don't want to wait any later than that or else your lemon balm may not have a chance to grow to maturity. Starting your lemon balm indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost has passed is on March 15 in Portland. It might get as low as 15°F during the coldest months of winter.

Since the USDA zone info for Portland is an average the actual date of last frost changes from year to year. Since half of the time in Portland there is a last frost after March 15 be ready to cover your lemon balm if you have one of those late frosts.

USDA Zone Info for Portland

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 Portland

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