They scratch. They gnaw. They sniff. They furiously dig with their little paws.

My cats.

This is one time their intrusion into the garden is not objectionable. Occasionally, they come along and view the garden not as an oversized litter box, but as a treasure-trove of plants that make them happy and wacky. The furry little beasts are incredibly funny when they roam the garden looking for some sort of pleasure – the kind they find rooting around like not-so-well-equipped little piggies with their tender noses in the rough garden soil. They roll in the catmint. They dig for valerian root. They leap for catnip leaves.

They nibble. They purr. They sack out for a nice nap in the sun.

Could these plants – or others – be useful to people, as well? Certainly!

The bounty from the garden often includes the most obvious produce: plump tomatoes plucked from the vine throughout summer, potatoes dug in autumn, root crops harvested from underneath a heavy layer of mulch throughout winter.

The harvest also may include a crucial family of plant material grown for healing. Gardeners interested in alternative medicine often turn to parts of flowers and herbs that have been shown to offer healing qualities. Although some medicinal plants are grown for their flowers – those of German chamomile, for example, are used in teas and are said to produce a calming effect – others are treasured for their leaves.

Did you know that through the ages leaves of the sage plant were viewed as a cure-all? The religious order of Shakers used sage in their herbal remedies to treat coughs, colds, night sweats, worms, sore throats and to produce perspiration. Historically, the plant was valued particularly as a woman’s herb.

Not all herbs are viewed as “alternative.” Mint and wintergreen can be found in a host of commercially prepared formulations that alleviate stomach ailments. Horehound, with its throat-soothing qualities, also may be found in commercially prepared lozenges and drops. Calendula, used in hand creams, is said to be helpful in healing skin.

There are a number of ways a gardener may preserve the healing quality of plants. Perhaps the most potent means is to produce a tincture. This practice is used in extracting the essence of specific, nontoxic plant material and storing the essence safely over time. The roots of echinacea, or purple coneflower, are used to make a tincture that reportedly boosts immune system function. Tincture made with roots of valerian is used in treating certain nervous disorders and is said to produce a tranquilizing effect.

There is so much to know in treating medical ailments with herbs that one hesitates to discuss it since oversimplification is a clear risk. References about herbal healing outline the procedure for preparing a tincture. A gardener seriously interested in self-treatment should undergo training with an herbalist or become well-read on the topic before ingesting plant extracts.

Naturally, absolute positive identification of plant material before harvest is a must. If there is any uncertainty at all about the identification of a plant in the garden, consult a reference or an experienced herbalist. Do not harvest any plant material for homemade cures that are infected by insects or disease. It is best to harvest organically grown herbs that haven’t been subjected to synthetic fertilizer or pesticides of any sort.

Tinctures are prepared by steeping plant material in a sealed glass jar in a liquid medium (usually grain alcohol) for several weeks. The jar should be clearly labeled with the contents – both plant material and steeping medium – and the date. Later, the plant material is strained from the tincture liquid. The finished tincture should be stored in a dark bottle to prevent damage from the sun and should, again, be clearly marked.

In preparing the tincture, the alcohol extracts vital chemical components from the herbs. The resulting liquid contains a concentrated chemical solution that contains the healing benefits. The solution is administered under the tongue by a dropper or in a more tasty glass of juice or tea, to improve flavor.

Typically, vodka or gin is the medium used to steep the plant material. To improve the flavor of the tincture for ingestion, brandy or rum are also used. For those who find taking in alcohol objectionable, plant glycerin, found in most natural foods stores, may be used as a steeping medium. Wine cannot be used for tinctures, since its alcohol content isn’t great enough – 40 to 100 proof is necessary. But, certain vinegars can be used. White vinegar should be avoided, but wine, cider and rice vinegar may be used to steep the herbs.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, 512 North Ridge Road, Montville 04941, or e-mail dianagc@midcoast.com. Selected questions will be answered in future columns. Include name, address and telephone number.