Growing Rhododendrons and Azaleas

Ten Ways to Kill a Rhododendron

Marjorie Hancock | Mississauga, Ontario | 1982

This article appeared in the Journal of the Rhododendron Society of Canada, Bulletin 1982, Volume 11, No 1, pp 16-19.

The rhododendron is an exotic plant in Southern Ontario. That simply means that it originally came from somewhere else. My father likened exotics to animals in a zoo. They are held captive in our gardens, and must be given conditions that resemble their native environment or they do not thrive and share with us their wonderful potential. Rhodos, in particular are very strange creatures. On occasion I have suspected that each plant has its own individuality; perhaps you could call it a soul. As with humans, their environment greatly affects their health and serenity. As with humans who are suffering, there are symptoms which tell us that they are miserable. But, as with humans, they seem to have a totally incredible will to survive. How often have you heard someone say, “I have a rhododendron in my garden. It looks terrible. The leaves are all blotchy and yellow and scabby, and the plant is scraggly, but I cannot bear to dig it up because every June it blooms like mad with the most gorgeous flowers!”? Just like humans ­ some of them survive and blossom, even under the most adverse conditions.

But back to my topic ­ how to kill them. (This is not my favourite hobby, by the way!)

Method No. 1 - Brutal Murder (Planticide)

One would think this would be the most expedient method. I've tried it. With almost any other type of plant, this is an easy way. Just dig it up and leave it on top of the ground. With rhodos, however, this does not always work. As a breeder, during the blooming period, I have roughly pulled unattractive hybrids out of the bed and viciously pitched them on top of the ground. The flowers faded and the plant wilted, but many were still alive in August because their roots were still touching the ground. In the nursery we must discard ailing or scrawny plants at transplanting time. Often they are still alive when cremated many weeks later. Or some are lifted for winter storage and set on the ground and perhaps forgotten in the fall, and those plants are still alive the next spring when the snows melt. I have several rhodos in the woods that were positioned for planting after use in a flower show but were never put in the ground. They are still alive and quite healthy looking, with only leaf drop around the root. Clearly, digging them up is not a foolproof method and must be considered a last resort, combined with chopping it into little pieces!

If you have analysed why Method No. 1 is unsatisfactory, you have a lead. Exposing the roots to the air does not kill them... Ergo - depriving them of air might do the trick. So we have:

Method No. 2 - Suffocation

Insert the roots deeply in the ground and tamp them in firmly. As a safeguard, raise the soil level well up the stem. This usually works, although the rhodo will struggle to resist by growing a collar of new roots, just centimetres below the surface, and inches above the crown of the root. Again, not foolproof, but if combined with Method No. 3, following, might be successful.

Method No. 3 - Drowning

This is best accomplished by first planting your rhododendron in very dense soil, in a hollow with poor drainage and holding it down with plenty of dirt. This is virtually guaranteed to work. Drowning can be accomplished even in a raised bed however, if someone advised you to plant it that way. Just water it a lot, say twice a day, even if it rains. This is slower and may not work too well, unless combined with Method No. 2. Be sure to use heavily chlorinated water, which leads us to:

Method No. 4 - Poisoning

Just as there are many subtle ways of disposing of people with poison and not getting caught, there are ways to poison a rhododendron. For instance: plant it within the root system of a black walnut tree. This lovely tree exudes a toxin in the soil which will do in your rhodo. Or you could feed it generously with Aluminum Sulphate. This is often recommended by ill-informed garden centres as a beneficial means of fertilizing, but the aluminium ions which build up in the soil will insidiously poison your plant in time, and no one will ever know what you have done!

Or you could simply plant your rhodo in sticky alkaline clay without amending the soil. This of course combines poisoning with suffocation and drowning and is an ideal solution to your problem. If you happen to have naturally acidic soil, increase the pH by adding large quantities of lime. Your rhodo will gobble it up and will not be able to eat its recommended balanced diet and will get very ill and will perish.

This business of diet leads us to several other approaches.

Method No. 5 - Starvation

This is not the easiest way to get rid of a rhododendron and can only be accomplished by closely following these rules:

  1. Plant in pure, sterile sand, in a totally exposed area, away from trees or plants of any kind (especially pines and oaks) and never allow leaves to collect under the branches.
  2. Never provide additional mulch.
  3. Never fertilize.
  4. Never water, even in drought periods.

Method No. 6 - Overeating

This is bad for people and can be very bad for the well-being of a rhododendron. It can eventually lead to death. A moderate diet of proper proportions is necessary for good health. If one provides an over-abundance of food which encourages too much growth at the wrong time of the year, the resistance of the plant is lowered and the rhodo will succumb to such ailments as indigestion, rashes along the edges of the leaves, sunburn and frostbite.

Method No. 7 - Malnutrition

This is rarely fatal and your plant will linger, unless you are aware of the following fact: you must keep the pH of the soil either extremely low or very high (at least 6.5 pH, preferably much higher). This will suppress appetite; your rhodo will not feel up to eating what good foods are available, thus encouraging a wide assortment of problems, particularly anaemia (chlorosis), indicating a lack of iron (or phosphorus, magnesium, manganese or other nutrients), making it more susceptible to a natural death from attacks of fungi or insects. Of course, you can speed the process by combining this method with other methods already described.

Method No. 8 - Overexposure

By this I do not mean showing the plant to all your friends! I prefer to designate this method Torture I, or Desiccation This could be a favourite with some gardeners, especially those in brand new subdivisions. Just plant your rhododendron by itself in the middle of the yard, or in an open field where it will receive the full blast of the dry arctic winds which we have in good measure from November to March. Alternatively, you might position it tightly against a white wall, preferably facing due south, and bake it to death in summer. Any temptation to provide windbreak in the winter, or to plant something else in the yard to provide light shade should be assiduously avoided.

Method No. 9 - Torture II / Trauma

Physical abuse can be inflicted on your plant. This procedure is not very satisfying, unless you are both a sadist and a masochist. Various avenues are open with this method, such as: have a spouse who hates plants (it happens!); have a very large family of primary and pre-school children (expensive!); have a very large male dog which is totally uncontrollable (a nuisance!); or have a resident gardener who insists on hoeing and digging up the beds twice a week instead of weeding (inevitable!). Vandalism by trespassers is occasionally helpful. Maiming falls into this category, i.e., cutting the plant down just above the ground level. Most of these do not work well and the plant is likely to just sprout again from the old wood.

Method No. 10 - Torture III / Ostracism or Mental Cruelty

Deprive your rhodo of compatible companions such as azaleas, other Ericaceae and Micorrizhae fungi, with whom it might develop rapport and come to feel a cherished part of the garden community. Refuse to provide resource and support systems such as Guardian Pines and Mentor Oaks. Plant it in a place where it cannot effectively compete with the giant corporations such as huge maples and willows, nor cope with the muggers of the plant world - the wild grape vines, wild cucumber, Creeping Charlie and brambles. Withhold your love and attention when it is really needed, or conversely, provide smother love instead of the studied neglect which allows it to develop its full potential and character in its own sweet time.

These are ten simple, home gardener ways to dispose of your rhododendron; all time honoured, but variably reliable under individual conditions. There are of course, more bizarre things you could do: import some whitefly or weevils or perhaps inoculate it with a fatal disease such as Phytophthora cinnamomi, a bit like a mad scientist.

I have heard that the best solution to a problem comes, not from the first or second idea but is found somewhere between the third and twenty-seventh suggestion, and is usually a combination of several ideas. So try the methods I have outlined or think up some of your own. If nothing works, I suggest that you just give your uncherished plant to another rhodo buff or a public garden and cancel your membership in the Rhododendron Society!