JARS v59n4 - A New Way to Root Blueberries - And Applies to Rhododendrons Too

A New Way to Root Blueberries - And Applies to Rhododendrons Too
Dr. Mark G. Konrad
Sewickley, Pennsylvania

Blueberries and rhododendrons are both members of the Ericaceae family of plants, but they have something else in common. Neither lends itself to easy or casual propagation. Experimentation with blueberries using an "air-wet" method has proved successful, and the same method has been used successfully with rhododendrons.
In an attempt to simplify and make propagation easier for the amateur, I have been experimenting with the following air-wet method.
Blueberry hardwood and leaf bud cuttings were taken in the fall, but probably the best time to take the hardwood cuttings would be late winter or early spring before any signs of vegetative bud break.
The hardwood cuttings measuring 4 to 5 inches are wounded on the distal stems but only on the upper side and placed on moistened absorbent paper (Fig. 1). Small squares of the same type of absorbent paper (1 in.) are used to cover the wounded sites and misted so that satisfactory moisture is maintained at all times. No medium is used. The container is covered with plastic sheeting.

Figure 1
Figure 1.
Photo by Mark G. Konrad

The same technique is used on the leaf bud cuttings, although in this case the two or three leaves on the cuttings are reduced by one half (Fig. 2). Hand misting is done as needed to maintain appropriate moisture levels.

Figure 2
Figure 2.
Photo by Mark G. Konrad

The containers are kept in shaded areas if outdoors or under fluorescent lighting if indoors. Hand misting is done as needed to maintain moisture and high humidity. Leaf drop has not been a problem.
Usually after a period of three or four weeks, when significant callusing has taken place (Fig. 3, 4), the cuttings are transferred to 9-inch pots with the currently preferred potted mix of equal parts of perlite and vermiculite. Clear plastic sheeting is then laid over the potted plants to maintain high humidity until rooting takes place.

Figure 3 Figure 4
Figure 3.
Photo by Mark G. Konrad
Figure 4.
Photo by Mark G. Konrad

For growing on, the best approach might be a heated greenhouse or indoors under fluorescent lighting. If these are not available, cold storage in a polyhouse or coldframe might be considered.

The advantage of this approach is that the callus forms under generally aseptic conditions by sealing off the exposed wounding. Blueberry cuttings of all types callus readily and can be a significant indicator that rooting will take place. In my experience, a hindrance to successful rooting has been the early vegetative bud break occurring before adequate callus formation has taken place. So far, with the air-wet method described above, the bud break is delayed while significant callusing is taking place.

The air-wet technique described above seems to be a promising alternative for rooting blueberries and has also been successful with rhododendrons. My early work with roses is very promising too. It is still too early to determine if there is any application for deciduous azalea hardwood cuttings or other plants.

Mark Konrad, a member of the Great Lakes Chapter, is a frequent contributor to the Journal.