Nurturing Herb Roots

The Heritage Herb Garden at the Ozark Folk Center graces the park with visual colors and textures, sweet and pungent aromas. With their natural display, the herbs help us to interpret the history of the human use of plants.

There is much more growing on our herbs than what meets the eye. Being familiar with the plant parts that we cannot see are very important to successful cultivation. Subterranean growth includes roots; these appendages secure plants so that they can grow upright. Roots absorb water and soil nutrients through tiny hairs. This solution moves upward through the roots, the stems and out through the leaves. Food produced by photosynthesis in the leaves moves back down through the vascular system to the roots.

Microorganisms living on and around the plant roots, together with the roots create a zone called the rhizosphere. This term was coined by a scientist named Lorenz Hiltner in 1904.

Russian studies have shown that roots not only take up water and nutrients but also excrete CO2 and other acids into the rhizosphere. These excretions feed and nurture beneficial microbes which, in turn, digest and make the minerals soluble in the growing medium. Phosphorus, which is not water soluble, is made available to the plant through the action of carbonic and nitric acids that are present in this root zone.

Mycorrhizal fungi live in healthy rhizospheres. These fungi live in symbiotic partnership with plant roots and helps plants resist disease. As mycorrhizae multiply, they extend hyphae (the vegetative growth of fungi, collectively called a mycelium) into the surrounding soil. As they travel, these hyphae contact soil nutrients and exude acids and enzymes that make the nutrients soluble so that plants can take them up. Plant roots are surrounded in a protective sheath of mycorrhizae that both encourage friendly organisms and discourage the growth of plant pathogens (a cause of disease). This has been shown numerous times in field trials.

The best way to encourage mycorrhizal fungi is to make and use compost. Incorporate compost in to the soil when planting, apply it on the soil surface under existing plants and spray compost tea on leaves. Studies show that compost tea sometimes helps to suppress foliar plant diseases.

To make compost tea, use a five-gallon plastic bucket with two gallons of water added. If you are using city water, stir and allow time for the chlorine to escape (at least overnight or 24 hours is best). Use an old sock for a tea bag. To the sock, add three cups of compost and one cup of alfalfa meal (alfalfa meal can be purchased in pet or feed supply stores). Tie off the top of the sock. Add about a half-cup of sorghum syrup or molasses to the water. Stir to dissolve. Sink the sock in the water. Install an aquarium bubbler or stir the tea twice a day, without fail. Brew for three days. Filter the tea through old T-shirt material or other loose-weave cloth before filling your sprayer. Spray plants before sunrise or just after sunset; never foliar spray when the sun is shining.

Roots are important, certainly, however, they are not the only plant appendages that grow beneath the surface. Stolons, rootstocks or rhizomes, which are found on mint and oregano, are creeping or repent stems that run along or just under the soil surface, striking roots. These have obvious sections consisting of a succession of joints or nodes. When growing under the surface of the soil, rootstocks produce scales that have buds which are modified leaves. These underground stems are capable of producing completely independent, new plants. As those of us who grow mint and oregano know, those creeping stems must and will grow outward from the original plant.

Bulbs and corms include the Alliums such as garlic, chives and garlic chives. These plant parts store nutrients in fat, subterranean parts that are truly stems. When we divide and replant bulbs and corms, we produce new plants.

Tubers are thickened rootstocks that have buds (eyes) on the sides. The buds produce roots for absorbing nutrient solution, stems and leaves for photosynthesis and finally, stems that bear leaves and flowers. Potatoes and Jerusalem artichokes are tubers.

Roots and underground stems can spread hundreds of feet or even miles, depending upon the species of plant. In a 1937 study, by a researcher named Howard Dittmer, a winter rye plant that was only twenty inches tall had roots that, when measured end to end, were 380 miles long. Consideration for the spatial needs of roots is often overlooked in gardening and especially when growing potted plants.

Correct spacing to accommodate the spatial needs of the roots and other underground parts of your herbs will produce healthy plants and a garden that is pleasing to the eye. Knowing the difference between roots and stems will empower the gardener with propagation tools and better planning. The use of compost and organic fertilizers will feed the soil and the rhizosphere around plant roots which will, in turn, feed the plants. Digging deeply into underground plant science stimulates growth for the gardener and the plants. If I don’t see you in the future—I’ll see you in the pasture!