by Bob Purvis
I’ve done a lot of bench grafting over the past ten years and then grown the trees in pots or in the garden or (more recently) in a pasture. There have been some good success stories, but also some disappointments. Here are some lessons I’ve learned in the horticulture department of the University of Hard Knocks to pass on to members of the Alaska Pioneer Fruit Growers.
The first has to do with the care of plant materials. With regard to rootstocks, it is essential to keep moisture levels in storage high enough that they don’t dry out, yet no so wet that mold develops. It’s okay to let the rootstocks warm up for a day or so before you graft them. Be sure that the rootstock you graft is alive and in good health, especially if you are using scion wood that was hard to obtain or of thin caliper.
With regard to storage of scions, plastic bags and a refrigerator temperature of 30-36°F is fine. It’s a good idea to add a slightly moist paper towel to the bag, and to check the bag every week or two to make sure it’s not sopping wet inside, which can lead to the scionwood’s developing mold. If you are grafting stone fruits—apricots, plums, or cherries—be sure the wood you use is completely dormant when you graft, and the grafts (at least for apricots and plums) should be kept at room temperature to promote rapid callousing.
Many of you have developed a fair degree of proficiency as grafters. The real test now is not how well you make your cuts, but rather how you care for your grafts after the buds begin to break through the wax. I’ve had good results keeping the roots of the rootstock covered with bark shavings or sawdust and watering this lightly and frequently. I now would use 5-gallon pots with holes in the bottom, sitting in 5-gallon buckets, so that any excess water will drain-away from the roots. If you can make up a light soil mix from potting soil and sand and replace the bark shavings or sawdust with this during the period between the graft’s beginning to grow and planting them in the garden, nursery row, or pots, you should get some good hair roots to grow.
Seedling apple rootstocks generally have a fairly good root system. I’ve had the worst problems with pear rootstocks and pear trees. Experience here in Washington State has shown that pears are much more subject to transplant shock than apples. Therefore, if you want to try grafting and growing some summer pears, consider buying your pear rootstocks and planting them in soil in pots immediately after grafting—or better yet, grow them for a year in pots and then graft them if you can wait that long. The newly grafted tree will grow a lot more vigorously with a two-year-old root system.
If you plant your grafts out in a special nursery area in your garden, do all you can to ensure your soil is in good shaped and do not rush the season. I had apricot and apple bud grafts killed by 22°F cold outdoors on May 3 of this year here in Selah.
Only allow one bud on the scion to grow, if two or more begin to put out leaves. It is far better to have one long shoot than two short ones, and the more horizontal shoot will be too low to the ground to be a permanent scaffold limb on the tree.
Once the growing season is underway, strive to see that soil moisture levels stay fairly constant, neither too wet nor too dry. Don’t plant grafts in extremely sandy soils, or if you must, work some organic matter or heavier soil into the rows. Be sure that you control weeds. Consider occasional watering with a liquid fertilizer product such as Miracle-Gro at the label rate or less. Another good practice, as soon as 6” of growth has been produced, is to stake the young tree so that the growth is not damaged by wind.