In the fifth century B.C., the Greek physician, Hippocrates, wrote that chewing bark of a willow tree could relieve pain and fever. (No wonder squirrels don’t get headaches.) In 1829, the effective ingredient, salicin, was successfully isolated from willow bark.  Toward the end of the 19th century, The Bayer Company in Germany trademarked a stable form of acetylsalicylic acid, calling it “aspirin,” the “a” from acetyl, “spir” from Spiraea (the salicin they used came from meadowsweet, Spiraea ulmaria, subsequently renamed Filpendula ulmaria), and “in,” a common ending in drug nomenclature.

In the 20th century, over one trillion aspirin, the first medicine created by techniques of modern chemistry, were consumed globally to regulate blood vessel elasticity, reduce fevers and aches, prevent cardiovascular ailments, affect blood clotting, or ease inflammation.

Native Americans and early settlers used willow bark for toothaches and applied it to the source of other pains. But they also recognized that you can actually grow a whole new tree by taking a stem and sticking it in moist soil. The hormones in willows cause rapid rooting, and they discovered these same hormones could induce rooting in other plants, too.

Willow water

To harness this power, they made a tonic called “willow water” by collecting willow twigs, trimming the leaves, immersing the stems in a pail of water, and pouring the water on newly planted trees, shrubs, and bedding plants. Commercial rooting preparations contain a synthetic form of indolebutyric acid (IBA) and growing tips of willows contain high concentrations of IBA, depending on the quantity used and length of time you soak them. Any willow (Salix) tree or shrub species will work.

Another discovery: In the January, 2004 issue of The Avant Gardener, a monthly newsletter to which you can subscribe for $24/year at Horticultural Data Processors, Box 489, New York, N.Y. 10028, editor Thomas Powell notes that gardeners reported all sorts of plants growing remarkably better when given regular doses of tiny amounts of aspirin (1 part to 10,000 parts water; larger doses actually proved toxic),” and that The Agricultural Research Service is investigating the reasons behind aspirin’s beneficial effects.

Plants make salicylic acid to trigger natural defenses against bacteria, fungi, and viruses. Aspirin thus is an activator of ‘Systemic Acquired Resistance’ (SAR). However, plants often don’t produce the acid quickly enough to prevent injury when attacked by a microbe. Spraying aspirin on the plants speeds up the SAR response. Tests have shown this works on many crops, producing better plants using less pesticide. “It also makes it possible to successfully grow many fine heirloom varieties which were discarded because they lacked disease resistance.” Powell says.

Scientists first encountered the SAR phenomenon in the 1930s. After encountering a pathogen, plants use salicylic acid as a key regulator of SAR and expression of defense genes. “Only recently have companies begun marketing salicylic acid and similar compounds as a way to activate SAR in crops—tomato, spinach, lettuce, and tobacco among them,” according to Powell.

“ARS scientists are studying plants’ defenses, such as antimicrobial materials like the protein chitinase which degrades the cell walls of fungi, and nuclease enzymes which break up the ribonucleic acid of viruses. They’re also testing aspirin and other SAR activators which could be effective against non-microbial pests such as aphids and root-knot nematodes,” Powell says. “This may be the most important research of the century. Stimulating SAR defenses with aspirin or other activator compounds could result in increased food production and the elimination of synthetic pesticides.”

He recommends we experiment by spraying some plants with a 1:10,000 solution (3 aspirins dissolved in 4 gallons of water), leaving other plants unsprayed. Tests have shown that the SAR activation lasts for weeks to months. (Sort of homeopathic heart attack prevention for your plants.)

Things to do:

Make your own willow water:
Easily root azaleas, lilacs, summersweets (Clethra spp.) and roses by gathering about two cups of pencil-thin willow branches cut to 1-3 inch lengths. Steep twigs in a half-gallon of boiling water overnight. Refrigerated liquid kept in a jar with a tight-fitting lid will remain effective up to two months. (Label jar so you won’t confuse it with your homemade moonshine.) Overnight, soak cuttings you wish to root. Or water soil into which you have planted your cuttings with the willow water. Two applications should be sufficient. Some cuttings root directly in a jar of willow water. Make a fresh batch for each use. You can also use lukewarm water and let twigs soak for 24-48 hours.

Ilene Sternberg is a freelance writer and amateur gardener with a certificate of merit in ornamental plants from Longwood Gardens, Pennsylvania and a former garden guide at Winterthur in Delaware.