JARS v46n4 - How to Create A Standard

How to Create A Standard
Clarence "Slim" Barrett
Greenleaf, Oregon
Reprinted from the Eugene Chapter newsletter, December1989

A "standard", of course, is a dwarf rhododendron grafted to the top of a long stemmed rootstock to create an effect similar to that of a rose tree. It can be spectacular as a focal point in the small garden as it is accommodated easily in a large, well drained planter.

The creation of a standard is normally a long term project but well worth the investment of time and effort. For rootstocks I prefer to use rooted cuttings of Rhododendron 'Anna Rose Whitney', but any robust grower that tends to put on long flushes of growth would be adequate. Rootstocks grown in fairly heavy shade tend to provide such long flushes of growth. From the beginning pinch off all side shoots so that all the vigor of the plant goes to the single upright growth. If the center bud gets accidentally broken off or dies, allow a single side shoot to develop and it will tend to grow straight up eventually.

'Anna Rose Whitney' generally grows over a foot each year, often 18 inches or more. When the plant has reached 5 feet or so, you can consider making your graft, although I prefer to wait until it is 6 or 7 feet high. At this height you may have to tie it to a stake so it doesn't fall over in the wind. I like to raise a whole bed of rootstocks as they tend to support each other, and a single stake can be used to support a number of plants. In the bed, plants should be about a foot apart each way so they can be grafted in place when ready. The best time to graft is when the rootstock is just finishing a flush of growth and is still a little soft. The scion, the cutting of a dwarf rhododendron that is to be grafted to the rootstock, should be the current season's growth but matured so that it doesn't make any demands on the rootstock for its nutrients or moisture until the graft has healed.

To make the graft you will need a very sharp knife, a plastic bag about 3 inches by 6 or 8 inches, a "twistee" and a rubber grafting strip, for which you may substitute a ¼-inch by 6-inch rubber band cut to form a ¼-inch by 6-inch T strip. Cut the scion 3 or 4 inches long and have it in your pocket ready for immediate use. With the sharp knife remove the top leaves of the rootstock to provide a 4 or 5-inch stub. Leave all other leaves in place. Cut off the top inch or so of the rootstock and discard it. With the knife split the stub of the rootstock down the middle about an inch or so. Remove all but the top three leaves of the scion and then cut both sides of the base of the scion to form a wedge about an inch long, coming to a point at the bottom end. Insert this wedge into the split you made in the rootstock, all the way to the bottom of the split, making absolutely sure that the cambium layer on one side of the scion exactly matches the cambium layer on one side of the rootstock. The cambium layer is the point where the bark meets the woody inner part, and this is the area where the rootstock will pass its nutrients and moisture to the scion and the point where healing will occur.

Since the rootstock will usually be ⅜ inch to ½ inch in diameter while the scion will be ⅛ inch or so one can easily insert two scions in each root-stock, one on each side of the split, thus giving a double chance of success.

With the scion or scions in place, carefully and fairly tightly wrap the rubber grafting strip around the union (point of graft) starting at the bottom and winding toward the top, leaving about an inch of rubber at the bottom and top, then tying the two ends together to keep the strip in place. Check to be sure you have not pushed the scions out of their proper alignment. Now place the plastic bag over the scion and secure it with the twistee below the union.

It is important that the newly grafted plant be in a shady area, as direct sun would quickly kill the scion. Leave the plastic bag on the scion at least several weeks.

Good scions to try are R. williamsianum , R. yakushimanum and its smaller hybrids, 'Creeping Jenny' (it droops)and any other really dwarf plant. Try to stick to elepidotes (non-scaly leafed) or you may run into problems of incompatibility.

The scions will grow quite rapidly once the graft has healed because of the robust root system of the rootstock as compared to the root system of a normal dwarf rhododendron. Once good growth gets under way, you may remove any remaining leaves on the root-stock and remove the plant to a more sunny location.