QBARS - v33n4 A Nurseryman Speaks on the Do's and Don'ts of Proper Rhododendron Culture

A Nurseryman Speaks On The Do's And Don'ts of
Proper Rhododendron Culture

Alfred Raustein, Holbrook, N.Y.
Reprinted from New York Chapter Newsletter

Alfred Raustein maintains a mini-arboretum and nursery in Holbrook. His beautiful plants attest to good gardening practices.

A question frequently confronting the Rhododendron grower is "why has my Rhododendron died?" In the majority of instances, the primary factor for such fatality is one of improper soil culture - meaning poor planting and growing conditions.
Yearly thousands of hybrid rhododendrons are propagated, grown on, and sold to the public. Unfortunately, many of these plants find their way to the compost pile, because the novice is not aware of certain basic requirements needed to develop these beautiful specimens into mature landscape plants. The end result is that numerous old, but fine varieties, suddenly fade out of existence, being replaced by a succession of new hybrids inevitably succumbing to the same fate as their predecessors.
Why? This tragic situation is a result of two practices - namely; using the hoe and the rake and secondly the indiscriminate use of fertilizers and acidifiers. This approach is an utter disregard of the special requirements of rhododendrons and other ericaceous plants, and such schisms have blinded the modern gardening public and in some cases the commercial grower.
The simple rules for proper care of these plants have been known for almost a century. Ignoring these basic rules by using Speed Ball Growing Methods means trouble in the long run. It is sad when one realizes that eminent explorers endured incredible hardship, even death, to bring these beautiful and precious jewels of Providence and Mother Nature out of the dense forests and wilderness into civilization only to be mistreated because of indifference.
Most of us can imagine how these plants must have been found growing in the wild. Do you believe there were modern day tools used for their cultivation along with high powered fertilizers to induce lush growth? obviously not! Just organic matter, assisted by the natural regeneration cycle kept these plants growing for decades.
At any new home site, whether it be on land stripped by the tract builder or on an established piece of land that had been properly cared for, the inexperienced new owner, because of unawareness, makes his sad and costly errors.
First, the impulse is to clean all beds of debris commonly known as mulch. This mistake is serious because you destroy surface feeder roots and subsequently expose them to the elements. Inevitably a slow death will ensue. Therefore, never cultivate surface rooted plants and surely avoid removing the protective mulch.
The use of peat moss has become popular as a mulch. Although a very important soil component, it is not a good mulch, because when dry it repels water, roots will tend to grow up through it and expose the delicate cells to variable and damaging weather conditions. Fertilizer added to peat moss and/or top dressings, other than in very early Spring, is impractical as it stimulates new growth, which will only be destroyed by early autumn frost. Actually, new growth needs the time to set next year's flower buds and harden off before Fall ends.
Mulch, on the other hand, performs a very important service to the plant in that it serves as an insulation factor, protecting the root system of the plant. Air pockets that exist between the layers of mulch actually increase the insulating ability. Oak leaves and/or pine needles (two to three inches) are ideal and small twigs or well rotted stable manure can be lightly scattered or top dressed, to prevent leaves from blowing away. Grass clippings should never be used, because they tend to mat, repelling water and air filtration, and during decomposition may overheat the soil. Fresh sawdust is not recommended.
The feeder roots of Rhododendrons are very delicate white threads, produced in great quantities, while the plant is in excellent growing state. These roots occupy the top three to four inches of the earth and plants planted too deeply must produce new surface roots, or because of such shock will set themselves back and die. Therefore, plant at the same level or slightly higher than the original growing environment - no deeper.
It should be noted that as mulch decays, it ultimately ends up as a powdery mold, furnishing the root system its needed nourishment. Plants do not eat like humans, or animals. They produce their own food through photosynthesis a process using air, sun and water. At times, fertilizing may become necessary and superphosphate and gypsum containing cottonseed meal, a tablespoon of sulfate of magnesium (Epsom salt) dissolved in a gallon of water should to the trick.
In closing remember: Your plant asks only neglect and receiving it - it will thrive. On the other hand, if given too much tender care and resultantly disturbed, it most likely will perish.