On Growing Rhododendrons On Logs
Cecil C. Smith, Aurora, Oregon
growing on a large fir log.
C. Smith photo
In rain forests of East Asia, rhododendrons grow on rotten logs and even in the decayed mosses and lichens on live trees. The roots do not penetrate into the sap of the host trees, however.
Many species and hybrids are growing well on logs and stumps here in the Northwest, including repens and its hybrids and williamsianum .
In our garden, several species in the maddenii series as well as R. moupinense and the cross, R. 'Cilpinense', are very happy on logs with a minimum of care. Several forms of bullatum are growing especially well in the above medium, better, I believe, than they formerly did in the ground.
The roots penetrate rotten wood very rapidly, and the plant seems to establish itself more quickly than in the ground. They will withstand dry conditions with less irrigating than do those planted in the conventional way. At first I had wondered about the nitrogen balance, but these plants have never shown any deficiency even with a comparatively small amount of nitrogen. They have always been in wood which has decayed sufficiently to he dug with a shovel.
A decided advantage of this type of planting for these early blooming rhododendrons is that they are elevated four or five feet above the ground. This diminishes the chance of frost damage to the blooms. (FIG. 56)
These experiences have been with logs and stumps of fir, the dominant tree species in this area. The bark and heart wood of an old fir stump are slow to decay, while the two or three inch sap area will break down rapidly. If a pocket is made in this decayed sap area, and the root ball of a small plant is flattened out to fit in, the roots will soon spread out, and the plant should do well.
I have found that this type of planting has required the minimum of care. In fact the only difficulty encountered was that all available logs and stumps were too soon planted.