One of the best tools that you have as gardeners to help us determine 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.

In Waltham you can estimate when it's the best time to plant lemon balm by reviewing the USDA zone info.

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 some cold which means that you can plant them just a tiny bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant lemon balm in Waltham 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 fully mature. You can get started a few weeks earlier by starting your lemon balm indoors.

Last Frost Date

On average the last frost is on April 15 in Waltham. In the coldest months of winter you should expect an average low temperature of -10°F.

Since the USDA zone info for Waltham may not be accurate from year to year the actual date of last frost is different every year. Since half of the time in Waltham you get a frost after April 15 be ready to protect your lemon balm if you have one of those late frosts.

USDA Zone Info for Waltham

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 Waltham

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