One of the first steps you take when you are estimating 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 Waltham can be used to determine when to plant monarda.

Planting Calendar for Monarda

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

You can plant monarda a bit earlier in the year because they are barely cold tolerant.

The earliest that you can plant monarda 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 monarda and expect a good harvest is probably August. You probably don't want to wait any later than that or else your monarda may not have a chance to fully mature. If you are starting your monarda indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on April 15 in Waltham. It might get as low as -10°F during the coldest months of winter.

Since the USDA zone info for Waltham may not be accurate from year to year the actual date of last frost changes from year to year. Half of the time in Waltham you get surprised by a frost after April 15 so make sure that you are prepared to cover your monarda 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.