Diggin' In: Good mint, bad mint: This one is great for the garden

July 13, 2015

Mint is often loathed because it spreads aggressively.

Mountain-mint, however, is quite different.

In fact, there is much to like about mountain-mint, according to native plant expert Helen Hamilton of Williamsburg, Va.

First, it attracts bees and butterflies. Secondly, it does not spread aggressively. Thirdly, deer dislike it. Lastly, its small white flowers are tightly clustered on the ends of stems and smartly structured so wasps and other short-tongued insects can easily feed on it, she says.

The common name "mountain-mint" does not refer to its mountainous origin, according to Hamilton.

There are two perennial versions of mountain-mint that home gardeners throughout the eastern and central regions of the United States and Canada might like to grow, according to Hamilton. In southeastern Virginia, where winter was unusually harsh and snowy, especially in February, mountain-mints returned with a flourish this spring and summer.

Slender mountain-mint (P. tenuifolium) has narrow leaves and an elegant airy look. It produces small white to lavender flowers that appear in dense clusters at the ends of slender, hairless stems.

Clustered mountain-mint, P. tenuifolium muticum, has dark green leaves that are wider and smell like spearmint when crushed, Hamilton explains. Each flower cluster bears striking silvery leaf-like bracts at the base, and the plant looks like it’s dusted with snow.

Both mountain- mints are ideal for pollinator gardens because they attract a variety of insects looking for nectar, including bees and the great black wasp.

"Mountain-mints are easy to grow in the home garden, in full sun or part shade," says Hamilton.

Great black wasps look menacing but they are not aggressive — their name reflects their large size, up to 35 mm or 1½-inches long, according to Hamilton.

"This is a stunning large wasp with a satiny black body and smoky-black wings that have a shiny blue iridescence," she says.

July throughSeptember, wasps of many kinds – cuckoo wasps, bee wolves, potter wasps and grass-carrying wasps — seek nectar on flowers, especially mountain-mints, milkweeds, goldenrods, common boneset and rattlesnake master.

"Wasps need a lot of the nectar for the carbohydrates and water that sustain their activities over the summer," she says.

"While the sole purpose of the male is to achieve mating, the female must build and provision a nest, lay eggs and raise the young. Males do not have stingers, but females will sting if their nest is disturbed."

Great black wasps (Sphex pensylvanicus) and their relatives are beneficial insects, controlling the numbers of grasshoppers, locusts and cicadas that feed on farm crops and garden plants. The wasps are common in the eastern United States, and can be found where their prey lives: meadows, pastures and yards.



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