Evergreens are plants which retain live foliage from one season to the next. They are an important group of landscape plants for the homeowner.

Evergreens supply color to the landscape when other trees and shrubs are bare in the winter months. Most garden or landscape designs can be improved with careful use of these plants along with a variety of deciduous plants (those which drop their leaves in the fall).

Evergreens can be divided into two main groups: narrowleaf and broadleaf varieties. This classification is usually adequate in determining the major foliage characteristics of a given plant.

Most narrowleaf evergreens have foliage that is quite long and needle-like or even scale-like on the stem. On the other hand, broadleaf evergreens develop foliage that has some degree of width to their leaf. The ratio of width to length can vary greatly among the different types of plants.

In addition to the variation in leaf shape, the narrowleaf plants generally do not develop flowers, at least not like an ordinary garden flower. Flowers on these plants are usually quite inconspicuous. The seed is produced in a cone. Some cone-bearing evergreens include pine, fir, spruce, juniper, hemlock and cypress.

The broadleaf evergreen group is a bit more diverse in its flowering habits. Some of the flowers are quite small. In addition, the seeds of most broadleaf evergreens are produced in an ovary which ripens to form a specifically shaped and often colorful fruit. Among the evergreens in this group are hollies, boxwoods, rhododendrons, pieris, mountain laurel and mahonia.

Evergreens may provide green color all year long, but the individual needles don’t live forever. Conifers periodically shed their oldest needles while retaining some foliage year-round.

Evergreen needles have varying life spans, depending on the species. Arborvitae and pines retain needles for two seasons, while spruce needles will remain on the tree for three to ten years.

Some species of evergreens have more noticeable leaf drop than others. In the fall, arborvitae and white pines drop their two-year-old needles and many people falsely believe their tree has a disease or is rapidly dying. The older needles of yews will turn yellow and drop in late spring or early summer.

Rhododendrons, broadleaf evergreens, drop their two- to three-year-old leaves in late summer and early fall. So, no need to worry about leaf loss on evergreens, if it’s not excessive and is restricted to old growth.

Don’t Guess, Soil Test:

Soil testing is a very useful gardening tool and can help you maintain a uniform level of soil nutrients for your plants. Soil should be tested every few years until a clear picture of nutrient use and balance has been developed.

Once a planting is established, less frequent sampling is needed. If plant quality appears to decline in future years, a soil test may supply the reason for the problem.

Repeated lime and fertilizer applications that are not based on a soil test may lead to toxic levels of some nutrients or nutrient imbalances that may take years to correct.

Soil samples can be taken any time throughout the year. It is important though to sample approximately the same time of the year. Late summer or early fall is a good time for most crops. This allows time for lime recommendations to react and change the pH before the crop is planted.

You can purchase a soil testing mailing envelope from county Extension office for $10.

“Growing Green” is contributed by Diane Dorn, Lehigh County Extension Office Staff, and Master Gardeners. Information: Lehigh County Extension Office, 610-391-9840; Northampton County Extension Office, 610-813-6613.