JARS v59n2 - Let's Talk Hybridizing; Hybridizing As Viewed by the Society Bretonne du Rhododendron

Let's Talk Hybridizing; Hybridizing As Viewed by the Society Bretonne du Rhododendron
Marc Colombel
Fouesnant, France

The creation of the Societe Bretonne du Rhododendron in 1993 initiated hybridizing as a hobby. The interest developed slowly as members began to see the results obtained by the earlier members. Those who stood by and watched claimed that they did not want to wait five to six years to see results and that they did not have the space. Some bought seeds from the seed bank but soon they wanted to create their own seeds.

In the beginning the hybridizer "bombards": he puts pollen on all different stigmas and even different pollen on the same stigma. When the seeds germinate, he keeps every plant fearing that he might eliminate the ultimate perfect wonder. When these plants flower he has to admit objectively that none are better than the ones already available. After they flower he further learns that the foliage is not outstanding either.

At this point he is ready to give up on hybridizing, but he is persuaded by the more experienced members to keep trying, this time by gathering more information from the literature and from others. I will try to give some of my personal opinions to a new hybridizer.

The total plant must be considered. The plants must have 1) nice foliage, 2) nice flowers, and 3) good shape. The flowers last for a few weeks so it is imperative that the foliage be attractive the remainder of the year. Flower color is a personal taste, each person with likes and dislikes. To me the abundance of flowers is more important than just the color. Keeping these traits in mind, the good hybridizer might be called a "good and strict selector."

In discussing leaves and flowers, I select for quality and abundance. Leaf quality includes tolerance for sunlight. Most new homes today do not have large trees in their garden so the plants must be able to withstand a lot of sun. In my seedling bed, at the end of summer I eliminate those plants with yellowed or chlorotic leaves. I notice that the ones that look really good and have thick leaves. Very quickly we learn to begin selecting tiny seedlings with thicker leaves. The abundance of leaves is characterized by how many years the leaves are retained. Those which keep only the current year's leaves will soon appear "twiggy" while some which keep the leaves for two to three years appear healthy. In addition, the size of the leaves will determine the attractiveness of the plant. The hybridizer should consider these traits when selecting parents.

The quality of flowers includes how long they last. The purpose of the flower is to attract insects to pollinate it. Once pollinated, the flowers quickly wilt or discolor. Thus, if pollination can be prevented the plant will put on a display for a longer period of time. Plants whose flowers have empty anthers or sterile pollen might be selected but this takes time and experimentation to make such a determination. Some flowers lack stamens which quickly takes care of this problem. Another possibility is to look for polyploidy which usually produces nearly sterile flowers. As with the leaves, thicker or "fleshy" corollas will last longer. Some flowers are blemished before they are fully opened so these should be discarded quickly.

No. 9903 ('Nancy Evans' x 'Kilimanjaro').
No. 9903 ('Nancy Evans' x 'Kilimanjaro').
Photo by Marc Colombel

In discussing the abundance of flowers the following needs to be considered. Flower count per truss should be around fifteen so that it displays nicely on the plant. This judgment is made because a lax truss of a few flowers tend to hang down so that to really see the flowers one has to pick them up or wait till the plant is very tall to be able to look up into them. Furthermore, drooping flowers can be seen as wilted and ready to fall off. A globular or conical truss appears to have more vigor.

Aside from flowers, leaves and shape, consideration should be given to propagating the selected plant. It should be easy to root or produce in vitro. Resistance to disease is another consideration. Thus it is important to avoid pampering your seedlings. For example, keep watering to a minimum and rarely feed them allowing only the healthier plants to survive. The nursery industry depends on ease of cultivation, health and dependability to continue growing and distributing plants.

R. 'Rwain'* A cross by the author
- without stamens
'Rwain'* ('Kerneostic' x 'Lem's Monarch'), a cross by the author.
Photo by Marc Colombel
A cross by the author ("sans étamine" - without stamens).
Photo by Marc Colombel
R. 'Floribond'* The author's seedling bed
'Floribond'* (cross), a cross by the author.
Photo by Marc Colombel
The author's seedling bed.
Photo by Marc Colombel

General guidelines:

1.The first two years of culture (from sowing to a root ball of about a 4-liter container) eliminate those plants which probably will not survive for the average gardener.

2. Plant the 2-year-olds in the ground in full sun, average soil and minimal watering. This is a good time to select plants for foliage.

3. After the third year, a few blossoms may appear. The first flowering may not be reliable, being smaller and colors may not be true. Allow another two years of blooming to make a selection.

These are basic guidelines with many exceptions. However, they are a good base in order to avoid growing too many plants or wasting time and precious garden space.

* Name is not registered.

Mr. Colombel is the founder and president of the Society Bretonne du Rhododendron.