QBARS - v6n2 Questions


The following are excerpts from correspondence addressed to the Secretary of the Society:

Q. Are there any true deciduous rhododendrons (not of the azalea family)?
Ans. Yes, possibly the most colorful and useful in the garden are dauricum and mucronulatum , the series Albiflorum, Semibarbatum, Trichocladum and a few of the Triflorum Series are also deciduous.

Q. Is root grafting successful and how is it done?
Ans. If you mean successful in a commercial way, I do not know of any grower who has adopted this method commercially. From an amateur point of view, I have found this method of grafting most satisfactory as it eliminates all possibilities of suckering later. As for the second part of your question; Select ponticum roots about the size of the scion. Either a side, cleft or saddle graft can be used. If the saddle graft is used split the end of the scion upward for an inch. Cut the top end of the root as a wedge and insert it into the scion. Bind together and either pot the graft or put it into damp peat moss in a propagating frame. Treat it the same as other grafts.

Q. Are there any rhododendrons which will tolerate lime?
Ans. A few of the species are found growing on limestone cliffs in the wild of China but it seems to be insoluble limestone because they do not grow well in limestone elsewhere. There are a few though, which do not object to a small degree of alkalinity, namely rubiginosum and hirsutum .

Q. What should the pH be for the successful growing of rhododendrons?
Ans. It is generally accepted that a pH reading of 4.2 to 5.5 gives the best growing range for the majority of Ericaceous plants including rhododendrons. The small leaved varieties can take a higher pH and the larger-leaved varieties can take a lower pH, or a more acid soil.

Q. When should one apply bait for the Strawberry weevil?
Ans. This should be a year around program to insure the best results. Here in the Portland area the weevil can be found in the ground during any month of the year. Generally speaking the bait is usually applied during the Spring months for the weevil and the spray is applied during the summer months for the Strawberry Beetle.

Q. Why is ponticum understock preferred in grafting?
Ans. It has been proven that R. ponticum will grow equally well on a wide range of soils even bordering on the alkaline side. It is also a known fact that many hybrids with R. griersonianum blood are not grafted successfully on ponticum understock.

Q. Can you tell me what is the cross of R. 'Mary Swatherling'?
Ans. It is R. 'Gladys' var. 'Mary Swathling'. A.M. 1934. It is considered one of the best varieties of Gladys.

Q. What is an azaleodendron?
Ans . It is a cross between a deciduous rhododendron (azalea) and an evergreen rhododendron.

Q. What is the matter with my 'Broughtonii Aureum'? The leaves are all brown and look like they are dying.
Ans. This is the winter color of the leaves for this azaleodendron. It will put out new leaves after flowering.

Q. Should azaleas be planted under Magnolias?
Ans. We often see this combination especially when both the Azaleas and Magnolias are small, but the time comes when the azaleas are crowded and need thinning. Being that Magnolias are surface rooters, they suffer considerably by having their roots disturbed and cut when the azaleas are transplanted. It is best, if possible not to plant too close to Magnolias.

Q. In hybridizing, how do you select the seed parent?
Ans. If a species is crossed with a hybrid, the species is usually selected to bear the seed; however it does not seem to make much difference as we usually make the cross both ways so that each plant becomes a seed parent.

Q. Can deciduous azaleas be layered?
Ans. Yes, azaleas root easily from young wood and can be cut away from the parent plant in about two years.