Following are a few of the gardening questions that I have received recently.

A reader brought me a sample of a weed and asked, “What is it?”

It took a little digging, but Jeffrey Derr, president of the Weed Science Society of America, identified it as clearweed, botanical name Pilea pumila, also known as Canadian clearweed and coolwort. His identification was confirmed by weed science specialist Andy Senesac.

This weed is related to stinging nettle but lacks the stinging hairs. It flowers from summer into fall in moist to wet woods, along streams and in woodland areas. The stems are smooth, can be rounded or ribbed, hairless and translucent.

The opposite leaves are ovate and coarsely serrated. Clearweed is an annual capable of creating thousands of seeds and forming large colonies. If your desire is to create a butterfly habitat, you may want this weed as the following butterfly caterpillars feed on the foliage: Milbert’s Tortoiseshell, Question Mark and Red Admiral. Otherwise, it seems best to weed.

The most interesting tidbit I learned while researching this plant was that American Indians used it to alleviate itching, to cure sinus problems and to treat excessive hunger, according to “Flora of North America.”

Pruning willow

A reader e-mailed: “I planted a Salix integra Hakuro Nishiki in my garden two years ago. It has grown significantly, but the new growth is all green. How do I get that white mottled leaf tinged with pink back?”

This Japanese variegated willow, also known as Dappled Willow, is a rapid grower with fountain-shaped branches and leaves that from a distance look white, but upon closer inspection are variegated. This plant looks beautiful in winter with twigs that are a coral red.

I have also wondered how to get the best color from this willow and researched the answer. What they need is to be pruned hard in early spring or late fall. You can also cut it back in July if new growth gets unruly. The best color is on the newest growth.

Overwintering tropical vine

A reader asked how to keep a mandevilla vine alive through the winter.

These vining plants have become increasingly popular and I expect there are many gardeners who would like to overwinter this tropical beauty.

By now, it should be indoors, as it doesn’t like temperatures below 45 degrees. Here’s the best course of action: Prune the vine back to 12 inches high, water only when the soil is dry to the touch and place the vine in a bright, sunny window.

Some people overwinter the vine in a heated garage. When Memorial Day arrives next spring and temperatures are no longer freezing, you can bring the plant outside for another season of spectacular blooms.

Happy gardening.