Rhododendrons may be planted any time from October to May. Unusual conditions might necessitate the moving of a large specimen plant during any of the other months and this could be done safely providing certain requirements are met. Smaller plants, whether grafts, seedlings, or rooted cuttings two or three years old, may be safely and satisfactorily be moved and planted any time that freezing conditions do not exist. Probably the most satisfactory way to illustrate the method of moving and planting one of the magnificent shrubs is to assume a hypothetical situation and follow step by step the entire procedure.
You have just purchased a two-foot, balled and burlapped rhododendron from your nurseryman and have chosen the location where year after year this shrub is to grow and flower.
A most important factor is the soil in your particular location, as soils are highly variable and many different types may be represented in an area as small as a city block. Special preparation is required if any objectionable conditions relative to texture, drainage, or chemical reaction are found.
First, the all important matter of drainage, which is so closely linked with the different types of soil and which is so vital to the well-being of the rhododendron, must be understood. If you live in the Northwest and are fortunate enough to live where fir trees grow naturally, it can be safely assumed that drainage is satisfactory. The fertility of the soil may in some cases be low, but drainage is always good. This also applies to gravelly or sandy soil, or shallow loams or clays with a gravelly or sandy subsoil that have a natural runoff and are not situated in a waterlogged depression.
If the soil is compact, heavy and sticky when wet, with a tendency to hold puddles of water for a long time after a rain, you can still grow fine rhododendrons, but some remedial measures must first be applied.
Many of the heavy clays have a subsoil that is impervious to natural drainage and it becomes necessary to inaugurate some means to carry off the water. As an open ditch is unsightly and at the same time a hazard to the gardener, tiling is the most economical and effective method to remove the water. The mistaken notion that drainage can be achieved by digging a hole in waterlogged soil and filling it with stones, gravel, or broken pots, still prevails with many gardeners. This procedure only aggravates the bad condition, for water will seep into the porous spot and remain there. The resultant stagnation will prove fatal to your rhododendron.
Setting The Plant
After you have solved the drainage problem next trench the soil to a depth of two feet or more. Throw out the clay, gravel or sand, and replace it with equal parts of good loam and peat. Peat is not absolutely necessary, but much better results are obtained when it is used. The diameter of the plant is the guide that determines the size of the hole. For example if the branches of your rhododendron have a spread of two feet, then dig the hole at least two feet wide. Here again no hard and fast rule can be set, and if the soil is heavy and packed, the hole should be even larger. In many loose types of loam it is necessary to dig a hole only large enough to admit the balled root system.
If your rhododendron plant has been dug for several days, soak the balled root system in water for half an hour before planting. Although it is not absolutely necessary, it is best to remove the burlap from the roots. Any of the types of waxed or tarred paper coverings positively must be removed. In the event that you have soaked the ball, place the plant in the hole before you pull the covering out from under it. The danger of breaking the ball and doing damage to the root system is greatly increased when the roots are soaked.
Set your plant to a depth of just a little deeper than the ground mark on the stem of the plant. This is usually quite apparent by the slight difference of color on the stem. It is a serious mistake to plant a rhododendron too deep, for this shrub is truly a surface feeder. Deep planting will stop the development and growth of the plant until a new root system is formed nearer the surface of the ground.
Now that the rhododendron is planted, it should be mulched with any of several suitable materials. Peat moss is neat appearing and to the liking of the rhododendron. It has the undesirable feature of acting as a water repellant when dry and requires considerable time to soak through. Decayed manure, oak leafmold, dried ferns, or pine needles can also be used. As your plant grows larger and becomes established fresh manure can also be used. Fresh manure from horse stables should be avoided because of the unfavorable alkaline reaction.
As previously mentioned, it may at some time become necessary to transplant a large rhododendron and the best time to do the moving is late Fall or Winter before the new root growth is made. If the moving is done after the new roots are formed the plant actually is living on what nourishment the ball contains.
Begin by excavating a trench all around the plant at a sufficient distance so as not to cut into the roots. The soil then is removed to a depth of eighteen inches and thrown back far enough so as not to interfere with the actual removal of the plant. After digging entirely around the root system, carefully dig towards the roots. When the first outer roots are exposed all around the plant, dig no closer. By brushing and rubbing with the hand much earth can be removed that does not contain roots. This greatly facilitates the moving operation by reducing the weight. What now remains is the entire root system encased in a circle of earth eighteen inches high. This circle of earth should next he undermined, being careful to stay below the lowest roots. When this circle has been undermined all the way around to a distance of one-fourth of the diameter of the circle, gently tip the plant over to one side. The root ball has now raised up several inches on the opposite side.
Into this opening place a rolled or wadded section of light canvas or burlap that is somewhat wider than the diameter of the root system. Then by tipping the plant back on its opposite side the wadded material may he pulled all the way through this opening. The plant, which may weigh several hundred pounds, is now resting on a section of material without actually having been lifted. The four ends of the material may now be used to lift or drag the rhododendron from the hole. If the new location is nearby, the plant may remain on the material and be pulled to its new site without being balled. In planting this large shrub the same directions for soil preparation and culture are followed as for the small rhododendrons.