December: Landscape Plants

Scale and Dormant Oil Treatment. Camellias, euonymus, ivy, in fact, most evergreen plants (broadleaf and needle, or scale leaf) can be infested with scale. We first notice a yellowing of the foliage. This occurs when the scale insect attaches itself to the leaf stems and branches near the leaves and then the backs of the leaves, inserts its little snout and sucks out nutrients from the plant. Step two is for the insect to lay its eggs on the plant and cover them with a smooth or fluffy whitish coating for safekeeping. Fortunately, this coating is easy to see and identify. It is distinct from the normal plant appearance and doesn't rub off.

Treatment during the growing season consists of pruning back of heavily coated stems and repeat spraying with a strong, systemic insecticide like "Isotox" or "Orthene." Hopefully, when the eggs hatch under the coating, there will be enough insecticide within the plant system to kill the new critters as they feed.

Winter treatment is far easier and non-toxic to you and the environment. When the plant is dormant you can apply horticultural oil to the entire plant. This oil will suffocate the eggs under the scale coating. For obvious reasons, this product is also called dormant oil. It must be applied when the ambient temperatures are between 40F and 85F and when no below-32F temperatures are predicted for the next 24 hours. This is the best treatment for scale. Take advantage of this opportunity to really rid your plants of a serious insect problem.

After the Ground Freezes top off the mulch around your roses, perennials, and bulbs. They need a little extra winter protection especially from what is called frost heaving. Frost heaving occurs when the frozen ground unfreezes during brief mild temperature periods, and then freezes again. The root masses or bulbs are pushed ever closer to the ground surface and become more exposed to cold. A thicker mulch layer prevents warm winter sun from reaching the ground and starting this heaving process.

Vegetable Garden. Ashes from wood fires may be spread over your vegetable garden to make it more fertile. They are the natural form of potassium or potash represented as "K" in the N-P-K of fertilizer formulations. Do not use ashes from coal fires. These contain toxins harmful to plants. Also, never burn pressure treated wood in your fireplace. It gives off fumes which are toxic to you. Most wood intended for outdoor use has been treated with chemicals for preservation. If you aren't sure, don't use it. It's not worth the risk.