Any fool can tell an azalea from a rhododendron. Being no fools, botanists can not tell them apart at all. In fact, what we call azaleas fall generally under the heading of rhododendron obtusum, its hybrids and allies. So anything pertaining to azaleas may be said to have general applicability to the entire genus rhododendron.
That being said, a discussion of growing conditions generally follows. Ever hear the expression, “Get a life?” This is what they were talking about.
The natural habit of the azalea is to take part in that general scramble of brush, which takes place in the cool shade of the forest under-story. They do best with part shade, though more sun often means more flowers and most will prosper densely in full sun. But we need something to flower in obscurity and azaleas do this better than anything else. There, beneath the oaks and pines they love best, azaleas grow primarily in the thick layer of decomposing duff–old leaves and wood–which carpets a grove. They really do not grow in the soil, given the choice. This has implications for the home gardener. First, dig your hole wider than deep, when planting an azalea. Put a two dollar plant in a ten dollar hole, they say. Half of what you put back in the hole should be peat moss. Heavy soil, clay, would do well to have sand and a handful of gypsum mixed in as well, but peat is the magic stuff–without which, nothing. It is the perfect substitute for that acid leaf-meal referred to by the poet, G.M. Hopkins, when he wrote, “...worlds of wanwood leafmeal lie...” And set an azalea shallow, not even as deeply as it grew in the nursery or container. Azalea roots dislike being buried deeply. A deep-set plant, if it lives, will be slowed for years by the bother of growing a new root system near the surface, while the old one rots away. Let the top inch or two of the root ball hump up above the surface of the surrounding earth. Shallow! And then cover the soil beneath the plant’s branches with mulch. This could be old leaves in the fall. They will self-destruct. Bark chips and wood chips are standard. Pine needles are excellent, both attractive and acid-forming, just the way azaleas like it. But anything is better than nothing. The exposed ground will dehydrate summer and winter, burning off hair-like roots in the heat and freezing them in the cold, or heaving the entire shrub out of the ground in the swinging temperatures of spring and fall. The last trace of peat moss will have vanished after seven years, research indicates. The couple of inches of fresh mulch a wise hand adds each year will gradually decompose to provide a substitute for the wasting peat below ground. There are a number of good reasons not to put mulch in the hole at time of planting. Peat’s the stuff, but do not try to use peat for mulch on the surface, or you will be sorry! Azaleas are not big feeders. If you want to give them a light fertilization in the spring, March is a good time. But the decomposing mulch will satisfy many of their needs. Definitely, never feed azaleas after mid-June, or the succulent growth which results will not harden to wood before sharp frost bites. Winter-kill will result.
A sea of new varieties have been developed in the last fifty years, and there is an overhang of wonderful old hybrids, dating back in a few cases to the Heian Period of Japan. Few are commonly available in garden centers, but specialty catalogs can help in obtaining them. Isn’t it funny how we so often settle for what we have always known?
appeared May, 2001
That being said, a discussion of growing conditions generally follows. Ever hear the expression, “Get a life?” This is what they were talking about.
The natural habit of the azalea is to take part in that general scramble of brush, which takes place in the cool shade of the forest under-story. They do best with part shade, though more sun often means more flowers and most will prosper densely in full sun. But we need something to flower in obscurity and azaleas do this better than anything else. There, beneath the oaks and pines they love best, azaleas grow primarily in the thick layer of decomposing duff–old leaves and wood–which carpets a grove. They really do not grow in the soil, given the choice. This has implications for the home gardener. First, dig your hole wider than deep, when planting an azalea. Put a two dollar plant in a ten dollar hole, they say. Half of what you put back in the hole should be peat moss. Heavy soil, clay, would do well to have sand and a handful of gypsum mixed in as well, but peat is the magic stuff–without which, nothing. It is the perfect substitute for that acid leaf-meal referred to by the poet, G.M. Hopkins, when he wrote, “...worlds of wanwood leafmeal lie...” And set an azalea shallow, not even as deeply as it grew in the nursery or container. Azalea roots dislike being buried deeply. A deep-set plant, if it lives, will be slowed for years by the bother of growing a new root system near the surface, while the old one rots away. Let the top inch or two of the root ball hump up above the surface of the surrounding earth. Shallow! And then cover the soil beneath the plant’s branches with mulch. This could be old leaves in the fall. They will self-destruct. Bark chips and wood chips are standard. Pine needles are excellent, both attractive and acid-forming, just the way azaleas like it. But anything is better than nothing. The exposed ground will dehydrate summer and winter, burning off hair-like roots in the heat and freezing them in the cold, or heaving the entire shrub out of the ground in the swinging temperatures of spring and fall. The last trace of peat moss will have vanished after seven years, research indicates. The couple of inches of fresh mulch a wise hand adds each year will gradually decompose to provide a substitute for the wasting peat below ground. There are a number of good reasons not to put mulch in the hole at time of planting. Peat’s the stuff, but do not try to use peat for mulch on the surface, or you will be sorry! Azaleas are not big feeders. If you want to give them a light fertilization in the spring, March is a good time. But the decomposing mulch will satisfy many of their needs. Definitely, never feed azaleas after mid-June, or the succulent growth which results will not harden to wood before sharp frost bites. Winter-kill will result.
A sea of new varieties have been developed in the last fifty years, and there is an overhang of wonderful old hybrids, dating back in a few cases to the Heian Period of Japan. Few are commonly available in garden centers, but specialty catalogs can help in obtaining them. Isn’t it funny how we so often settle for what we have always known?
appeared May, 2001
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