GRAFTING FAQ
Dr. William B Shell
When is the best time of the year to graft Japanese Maples?
The scion must be dormant, or nearly so; in late winter or in summer when the scion has hardened off (no active growth at the tip).
What is rootstock? Does it matter what rootstock you use?
Rootstock is the rooted part of the graft to which the scion is grafted. The scion and the rootstock must be compatible. Acer palmatum rootstock is best used with Acer palamtum scions. Acer palmatum is also compatible with Acer japonicum but not with Acer bergeriamum
What is cambium?
Cambium is the growing part of the tree. It is located on the outer edge of the tree. The inner cells of the cambium produce the woody part of the tree, while the outer cells of the cambium form the bark. The woody part of the tree is for support. The cambium contains the tubes which conduct the nutrients up from the soil (xylem tubes) and the phloem tubes which conduct the manufactured food downward. If you girdle a tree, you interrupt this flow and the tree dies.
What is grafting?
Grafting is joining the cambium layers of the rootstock to the cambium layers of the scion for some length of time. The graft heals (calluses) and the scion is then fed by the roots of the rootstock. The cambium layers of Japanese maples are very thin and much care must be taken when preparing the cuts so the cambium layers will not be damaged. A sharp grafting tool is absolutely essential.
Can you recommend a grafting knife?
I use the Tina 605, for righthanders. It is made out of special metals that will hold an edge. One side is flat and the other side is slanted about 23 degrees. I strop it after every twenty cuts or so. Vertrees used a single edge razor blade, which I do not recommend. I find it is much more difficult for me to control. What ever you use, it must be kept extremely sharp. One of the biggest causes for graft failure is damaged cambium.
Does the scion have to be the same diameter as the rootstock?
In an ideal world it would be nice if the scion were the same size as the rootstock, but that is seldom the case. After I make my cuts, I align the left side of the scion with the left side of the rootstock. I hold them in place with a grafting rubber until healing takes place. If the cambium layers are not touching, then no successful graft will take place. Care must be taken in wrapping the graft so as not to squeeze the cambium layers too tightly together, just tight enough to hold the layers together until healing occurs.
How long can you leave scions in the refrigerator?
I have left them in the frige for two months and made successful grafts. I don't recommend leaving them in the frige any longer than necessary. I place them in the frige in a damp paper towel with just a hint of fungicide and place the towel in a zip lock bag. I try to remember to label.
When is the best time to collect Japanese maple seed?
I collect Japanese maple seed (samara) just as the wings begin to turn brown in the fall. I prefer to not let them dry out. I place them in an equal volume of moist peat/perlite in a zip lock bag with a hint of fungicide for sixty-ninety days in the frige. As they germinate I plant them in 4 inch pots. If your seeds are dry, soak them in warm water for 48 hours and then treat them as above.
Can Japanese maples be grown from cuttings?
Yes. It seems most of the time the plant doesn't do as well on its own roots as when it is grafted. However, Bloodgood seems to do quite well. Give it a try.
Can Japanese maples be air layered?
Yes, but most of the time, you will have a stronger plant if it is grafted. Never be afraid to give it a try!
What is the best size rootstock to use for grafting?
I like for my rootstock to have a caliper of about 1/4 inch. Of course you can graft on smaller rootstock as well as larger. Remember, sharp knife and align the cambium layers!
When should the bag be removed that is covering the graft?
Be sure the graft has taken (callused) before removing the bag. I check after two weeks, and if the graft looks good , I wait another week and then loosen the tie to allow air to flow into the bag and then two days later I remove the bag. Sometimes it takes six weeks or longer for the graft to callus. Unfortunately, sometimes never. If the scion starts turning brown and drying out, be assured the graft has failed. Don't be alarmed! As your grafting skill improves, so will your percentage of successful grafts.
Can Acer buergerianum be grafted to Acer palmatum?
No. They are not compatible. However, Acer palmatum cultivar scions can be grafted to Acer japonicum rootstock and vice versa.
Is there any rooting compound or chemical that you can dip your scion in that will enhance your grafting.
Not any I have found or read about.
When should the top part of the rootstock be removed?
The rootstock above the graft should be removed as soon as the graft has taken well. I remove my rootstock tops after leaves begin to form on the scion.
When should the rubber strap be removed?
I do not remove the rubber strap. It deteriorates after a few weeks. This is not the case if you are not using straps made especially for grafting. If for some reason you are using straight rubber bands, then remove them after the graft has taken. I purchase my rubber straps from amleo.com.
I have difficulty aligning my cambium layers. Any suggestions??
I have begun using a "mageyes #5" head attached magnfying glass and it has helped tremendously. I use it to make all my cuts and to align the cambium layers. You can find it at mageyes.com
I placed Japamese maple seed in the frige in November in moist peat and a zip-lock bag. I just noticed some of the seed are sprouting here in February. Should I pot them?
By all means. Pot in good potting mix with good drainage, with not to much fertilizer.
© 2002 Dr. William B Shell. All Rights Reserved.