Yarb Tales
December 7, 2015

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

Understanding and nurturing of subterranean plant growth is very important to successful plant culture. In the garden, this past summer’s annual roots are long dead and in a state of decay in the earth or compost. These tissues are transforming into organic matter, the material that serves as a reservoir for water and nutrients and improves the tilth in soil. The decaying roots that are left in the soil are creating channels by which new roots may travel.

Hardy annuals such as cilantro, turnips and arugula, and biennials which include parsley, mullein and evening primrose; as well as hardy perennials from asters to zebra grass and all woody shrubs and trees are actively growing underground. This is true so long as the plants are alive and root zone soil temperatures are between 31° and 41° F. The following article about the studies of tree root growth confirms this statement and provides detailed information for those who wish to investigate further: http://northernwoodlands.org/articles/article/what_do_tree_roots_do_in_winter.

Mature, woody roots sprout fine, white feeder roots that elongate and absorb water and nutrients.  This happens during specific cycles of plant growth, at any time and at varying depths where the soil is moist and not too cold or too hot. During the late summer and throughout autumn and early winter, perennials have completed their aboveground growth. The soil becomes cool and usually, precipitation increases. At that time shallow roots grow rapidly. Roots are not as hardy as aboveground plant parts. Most die within two weeks, killed by a hard freeze or dry soil. Some will harden and become woody roots that sprout new feeder hairs that plunge deeper into the ground, below the frost line.

Even in winter, it is important to water the garden plants, which we wish to keep during dry spells. Apply a mulch of leaves, bark, compost or wheat straw around young trees, shrubs and perennials to moderate soil temperature extremes and conserve soil moisture. Just remember not to pile any mulch material up around the trunks of plants. This encourages damage by disease, burrowing insects and rodents.

Mediterranean herbs such as sage, thyme, lavender and winter savory should be watered during dry times too—winter is the wet season in their homeland. Mulch these plants with minerals such as coarse sand, fine gravel, lava rock or weathered shale. Mineral mulches will settle into cracks in the soil caused by alternating freezing and thawing. This protects the shallow feeder roots of perennial herbs and becomes a part of the soil structure for these exotics that originated in the rocky region of the Mediterranean.

Come spring the mulch will keep the soil cooler longer. Some old-time peach growers believed that they could delay bud break until after danger of late frost by keeping thick mulch around the trees from early winter when the ground froze, until late April. I learned this by word-of-mouth years ago. By contrast, vegetable gardeners remove mulch from the rows so that the soil will warm up for seed planting. In the Heritage Herb Garden mulch is left in place and new layers are added as needed. In this way, we continue to feed the soil with organic matter and replenish needed minerals. In turn, the soil feeds the roots and the roots feed the plants.

Nourish your roots. Then settle in with seed catalogs and gardening books knowing that the unseen work continues and spring is on the way. If I don’t see you in the future—I’ll see you in the pasture.