March 15, 1996

Plant Advertisements: Fact versus Fiction

Every spring, advertisements appear in newspaper and magazines extolling the virtues of plant material and garden products. Some of the advertisements are clearly fraudulent. Their claims are too unbelievable. The truthfulness of other advertisements is more difficult to determine. To help the home gardener, the claims of several advertisements appearing in newspapers, magazines, and catalogs along with important factual information are presented below.

Browning of Evergreens

Conventional wisdom states that winter injury on evergreens, often called desiccation injury, occurs when foliage transpires water on sunny, windy days during the winter when temperatures are above freezing. If the soil is frozen, transpired water cannot be replaced and the tree or shrub suffers desiccation stress (foliage browning and tissue death).

Garden Color

We hear a great deal regarding the use of color in the garden. Various combinations of color can catch people's attention while other combinations create a sense of space. Color can be envisioned as having three dimensions. The first dimension, hue, is the quality by which colors are distinguished from each other. The second dimension, value, defines the quality of lightness or darkness within a color. Those values darker than the particular color are called shades while lighter values are called tints. The third dimension of color is intensity.


A native of Mexico, marigolds have been grown in gardens throughout the world for hundreds of years. Today, they are one of the most popular bedding plants in the United States. Marigolds are easy to grow, bloom reliably all summer, and have few insect and disease problems. The marigold's only shortcoming (for some people) is its pungent aroma.

Black Mold of Onion

Black mold of onion is caused by the fungus Aspergillus niger. This disease can occur in the field or during storage. As the common name suggests, the primary symptom is a black discoloration of tissue. Infected bulbs may show blackening at the neck, streaks or spots of black on or beneath the outer scales, and black discoloration in bruised areas. In advanced stages, the entire bulb appears black and shriveled.