QBARS - v12n2 Rhododendron Notes

Rhododendron Notes

There is an increasing interest in the dwarf varieties and species. This may be partly due to changes in types of houses and styles of landscape gardening. Then there seems to be a trend for the gardener to become interested first in the large types, then as his knowledge of the genus increases, in the dwarfs and the species.

One of the desirable small types is the dwarf form of R. keiskei . It is extremely dwarf and flowers at an early age. We had several dozen seedlings bloom when only 2 to 3 inches high. The flowers were quite uniform, a light creamy yellow, and large for the size of plant, over an inch and a half in diameter. The flowers opened early, about with 'Cilpinense', and continued to open so that the blooming season of the individual plant extended over more than two months. Frosts which browned the petals of 'Cilpinense' did not affect the flowers of R. keiskei growing under the same conditions. The seed came from a plant growing near New York City where it seems to be quite hardy.

Not all rhododendrons require shade. Some of the dwarfs will do quite well in full sun if well mulched and well watered during dry weather.

A correspondent mentions an instance of azaleas being injured by frost to a greater degree when mulched than when not mulched. This is to be expected as the mulching material insulates the soil and prevents the radiation of heat which would tend to offset the colder air temperature. Only under certain conditions would such a difference be noticeable, and the advantages of mulch for all members of the genus Rhododendron far outweigh its disadvantages.

From Prof. R. L. Ticknor, of the Massachusetts Experiment Station, Waltham, comes a note telling of the observations of Hugh Bell of Nova Scotia on the development of blueberry seed. Bell reported that pollen tubes required about 4 days to grow from stigma to ovule. In some other physiological characters blueberries and rhododendrons have been strikingly similar. If it takes 4 days for the pollen tube to grow through the relatively short blueberry style, how long would it take for the rhododendron pollen tube to grow the much greater distance (on large flowered varieties at least) from stigma to ovule? If one wants seed, early pollination would seem desirable, so that the style will remain un-withered until the pollen tube has completed its growth.

Rhododendron breeders are urged to register their new varieties with the A.R.S. Registry. If you are just thinking of naming a variety please send the names you are considering to J. Harold Clarke, Registrar, for checking. We have available preliminary copy for the International Check List being published by the R. H. S. and which will contain, so far as possible, all names already used for Azaleas and Rhododendrons. We will be glad to check this list and see if the names you are considering have already been used.

- J. Harold Clarke

March 2, a beautiful spring day on the Oregon coast. At Donald Stryker's, located at Langlois, 300 miles south of Portland, the R. arboreum were in full bloom and several of the early red hybrids. A number of the very early species had already bloomed and gone. Magnolias stellata and soulangena were masses of flowers.

In contrast to our early spring and mild weather, Charles Dewey, Charlotte, N. Carolina, on February 27, wrote: "...the ground below 1½ inches is frozen hard. Every week end we have had rain or sleet or snow or bitter cold. This has been going on since early November. It has been near zero in the city and down to about 10° below in the country. Last year by the end of February my R. mucronulatum plants had bloomed and several azaleas were blooming."

Two reasons for rhododendrons not blooming well are planting too deep and in too much shade. To be safe plant a rhododendron at the same depth as it was in the nursery and then mulch it heavily. Several inches of light airy mulch on top of the roots is much different than several inches of heavy soil. Rhododendrons should have at least a half day of sun. They will not bud well in dense shade and grow tall and leggy.

"What kind of fertilizer should I put around the roots when I plant rhododendrons?" That question is often asked. The best answer is not to fertilize at that time. Heavy watering with the nozzle removed from the hose, is much more important. Then, if it is the right time of the year in your locality put the fertilizer on top of the root ball and wash it in.

First species in the new section of the Rockery at the Test Garden New section of the Rockery
Fig. 22.  Mrs. A. W. Kraxberger and the
Secretary of the Society in the foreground
plant the first species in the new section of
the Rockery at the Test Garden.
Fig. 23.  The new section of the Rockery
at the Test Garden will double
the size of the original planting.

The new rockery at the Test Garden, Portland, Oregon, is now nearing completion and planting commenced Saturday, March 29. (Fig. 22) This new planting faces the lake and the foot bridge, over which all visitors cross to reach the garden. It more than doubles the area devoted to dwarf rhododendrons and other rockery plants. While this new planting will relieve the crowded condition of the old rockery, many hundreds of additional plants will be needed. The Test Garden committee would be most happy to accept donations of good rockery plants.

- Bob Bovee