Volume 14, Issue 46 ~ November 16 - November 22, 2006

The Bay Gardener

By Dr. Frank Gouin

No Easy Fix for Wintering Plants

Anti-desiccant sprays just don’t work

Be wise when you hear glowing advertisements by manufacturers of anti-desiccant sprays like Wilt-Pruf, Vapor-Gard, Foli-Cote or Foli-Gard. Such companies claim that spraying the foliage with these prevents water loss, thus making the plant more winter hardy.

Those sprays do not work. Testing by myself and other professional horticulturists has shown that spraying evergreen plant foliage with these chemicals does not provide winter protection. Such sprays only help retain water from a few days to a week or two. Some sprays actually cause elevated temperatures within the leaves and buds of plants, which cause them to lose more water; dehydrated tissues show the symptoms of burns.

I recently tested a new product that supposedly improves the survival of newly transplanted Christmas tree seedlings. When I tried it, the anti-desiccant caused more of the seedlings to die than untreated seedlings. A young seedling that has lost many roots needs to transpire, or breathe, so it can photosynthesize, producing new roots. The spray was so efficient in sealing water within the leaf tissues that the seedlings could not photosynthesize and grow new roots.

There’s no miracle spray. Winter hardiness is genetic. You cannot improve a plant’s winter hardiness by spraying anti-desiccants. If you have an evergreen damaged repeatedly during winter, you should either discard that plant or find a more protected place for it.

Name the Mystery Plant

Q A mystery plant appeared beside our garage this summer. Out of curiosity we let it grow, and now it is a 15-foot-tall monster. Its leaves are two feet wide and long, heart-shaped and opposite each other on a stalk almost three inches in diameter at the base. Smaller leaflets are growing in some of the leaf/stalk joints, but the plant doesn’t have branches per se. Tropical Storm Ernesto broke off many of the larger leaves, but it kept growing.

I’ve seen similar plants at abandoned homesites and on the roadside, and I’ve seen the same plant used as an ornamental in the middle of a flowerbed at two or three houses. The bottom of the stalk is now starting to turn gray and woody, and it looks like it wants to become a leggy tree.

Any idea what it might be?

—Jerri Bell, Chesapeake Beach

A It is Pawlonia, better known as the Empress Tree. It is a fast growing tree and its lumber is prized by the Japanese. However, when it grows fast, its lumber is worthless. It has to be grown slowly to be of value for the making of dowry boxes, kotos and finished cabinets. It takes about 40 years to produce a sizable log. Its growth will slow in a couple of years.

Ask Dr. Gouin your questions at frgouin@erols.com. All questions will appear in Bay Weekly. Please include your name and address.

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