Upper South

September, 2008
Regional Report

Favorite or New Plant

Hairy Alum Root
Alum root, of the genus Heuchera, has gained wide popularity in recent years because of the many hybrids with all sorts of fantastically colored and marked leaves. These certainly are fun to add to the garden, but my favorite heuchera is more visually restrained but no less notable, especially because of its ability to grow well beneath a moisture-sapping silver maple. Heuchera villosa is commonly called hairy alum root because of its velvety-textured leaves. Although shaped similarly to the more dazzling heucheras, the leaves of hairy alum root are much larger, usually to 5 inches across.

The two most widely available forms are 'Autumn Bride' and 'Purpurea', with green and purple leaves, respectively. In winter, 'Autumn Bride' joins its compatriot, changing to a reddish purple leaf color. In late summer and early autumn, hairy alum root sends up wands of small white flowers. Best of all, it's a tough, adaptable plant that grows well in light to medium shade with dry soil.

Plants grow about 2 feet tall and as wide and are particularly useful as ground covers. They are deer resistant and native to rocky, wooded slopes from New York south to Georgia and west to the Mississippi River, leaping over only to Missouri. As might be expected with the interest in heucheras, there are more varieties beginning to be available, including 'Chantilly', 'Caramel', and 'Bronze Wave'.

Tool or Gardening Product

Biological Control of Colorado Potato Beetle
For the first few years that I grew potatoes, there were no Colorado potato beetles. Then a few showed up (How do they know there are potatoes and where do they come from?), and the potatoes survived. Next, I mulched with straw, which is said to disorient them. Finally, this year, the beetles were winning, so I tried neem several times. It knocked them back a bit, but they were still multiplying rapidly. Finally, I saw the consumer version of Bacillus thuringiensis subspecies tenebionisa at a local garden center. One spray did them in. Bacillus thuringiensis (Bt) is a naturally occurring soil bacteria that produces poisons that cause disease in insects. The bacteria must be eaten by larvae, so timing is important. Bt is not toxic to natural enemies of the potato beetle. Brand name products and their producers include Colorado Potato Beetle Attack (Ringer), Bt Leaf Beetle Attack (Safer), Colorado Potato Beetle Beater (Bonide), Colorado Potato Beetle Pre-Adult Control (Dragon), M-One and M-Trak (Mycogen).

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