Juniper Grafting Propagation

Very large cuttings (6-8” long with a caliper of a# 2 pencil) of Juniperus chinensis ‘Hetzii’ understock are taken between November and January the year before it is to be grafted. The cuttings are dipped in a 5,000 ppm IBA + 2,500 ppm NAA solution and placed into a 50:50 sand:bark media in a plastic covered quonset. The cuttings receive intermittent mist until they are rooted. Generally this takes about 3-4 months without supplemental heat.

The cuttings are left unsheared and grow throughout the summer. The cuttings are dug in late September and are brought to the propagation building where the tops and the roots are trimmed back to stimulate new growth. The understock cuttings are then potted in 3 1/2” plastic pots and placed on a bed of composted bark on a bottom heated bench. The understock is shaded and misted until the shock has passed. (About 2 weeks). When the understock has new blue growth on the top you can see new white roots through the holes in the bottom of the pot, it is ready to graft. As a reference, in Oklahoma, conifer grafting begins on the understock that is ready the Monday after Thanksgiving.

Scion Preparation
A scion about 6” long is cut from a stock plant 1-3 days before it is to be grafted. The fresher the scionwood, the better. The scion should be from the current year’s growth, with brown wood on at least the bottom 2 1/2”. The scion is trimmed up about 2” from the bottom and then wedged with a tapering cut on each side. The scion must have brown wood left down each side.

Understock Preparation.
Being careful not to cut all the way through the understock, make a long (about 2”) cut into the side of the understock down to the soil line. The cut should be angled slightly into the understock. Hold the top of the understock so that it doesn’t break off.

Joining the Stock and Scion
Using a scion with approximately the same diameter as the understock that you are working on, slip the scion into the cut on the understock. If the length of the scion doesn’t match your understock cut, recut your scion to fit. Align the cambium layers on both sides if possible. If this is not possible make sure that one side is completely aligned. Holding the understock with the aligned scion inside, wind and tie the budding rubber around the understock. It should be tight enough that when you hold up your finished graft, you should not be able to see light through it.

Finishing the Grafted Conifer
After the plant is grafted, it is taken back to the bottom heated bench and misted and shaded again. The composted bark that it had been sitting on before is now placed up around the grafted area. The moist bark is used to keep the wound from drying out until it heals. Welch Juniper will begin to show callus in about two to three weeks. After the graft has healed for about a month, 1/3 of the understock is removed. In March, about a month before the plants are taken to field, the upper part of the understock is cut off completely. The scion is never trimmed since this will be an upright juniper and it will need the apical dominance that leaving the terminal will provide. The graft is kept under the bark until early April when the grafted plant is then placed in a 1-gallon container and grown for 2 years. After two years, it is shifted to a 5-gallon container and then grown for another year before it is sold in the spring. From cutting propagation to salable 5 gallon upright takes