Rhododendrons are distributed across the world. They are mostly found throughout the Northern Hemisphere, except in dry desert areas. This genus comprises plants with colorful flowers, making them a popular choice for landscape gardens. Rhododendrons mostly grow into shrubs; a few may also grow into medium-sized trees. Because its seeds are produced in abundance, dispersing them is the best and natural way to propagate. They can also be propagated by using certain commercial techniques.
Cutting is a vegetative method of propagation. The new plant produced is genetically identical to the parent plant. In other words, it is a clone. In this method, a small section is cut from the parent plant and rooted in another spot to form a new plant. The size of the cutting (usually 1-4 inches long) depends upon the size of the parent plant. The section which is new, with a bud attached to it, is selected. Before rooting the new plant directly into the soil, it has to be put in a rooting bed. The temperature of the soil and the moisture retention of the bed has to be controlled.
Grafting is also a means of vegetative propagation. Grafting is slightly different from cutting. In this procedure, the part that is cut from the parent plant is rooted to another plant or tree (rootstock), that is already rooted in the soil. A V-shaped cut is made below the cutting, with a slit made in the wood of the rootstock, as well. The V-shaped cut is then inserted into this slit. The wood of the rootstock should be hard and of the same diameter as the cutting.
Layering is usually not practiced on a commercial scale. It can also occur naturally. It is a simple process in which the branch of a rhododendron that you wish to replicate, is planted in the ground. It is then covered with soil and water. It can be supported with some sort of weight to keep it in place. This is a slow process, as the new plant may take a couple of years to grow, before it can be actually separated from the parent plant.
Tissue culture or micro-propagation is a bio-technological process of propagating a rhododendron. It has become popular commercially, as there is bulk production. The method includes adding a piece of rhododendron wood into a test tube containing agars and auxins. Thermodynamic conditions are controlled and proper sanitation is maintained. The wood then produces many nodules without roots. Each nodule is capable of producing a rhododendron plant, when rooted in the soil.
This is a simple and natural method of propagating rhododendrons. The seeds are minuscule in size and can germinate within 3-8 weeks. Because the seeds are tiny, they need a smooth surface to sprout from. They cannot withstand the cold, so they should ideally be sown in the summer. After the seeds sprout, the sapling can be transferred to another pot. The new plant that is produced, looks exactly like its parent, but is genetically dissimilar.