I went back to Sky for another Saturday of fruit tree education. Bill Davis of the Western Washington Fruit Research Foundation took point and was assisted by Dan Vorhis of Sky (you may remember him from last weeks pruning class).
The lecture portion of this class wasn’t as rewarding as the pruning class last week. It wasn’t that I didn’t learn a lot: I was starting from absolute zero in my understanding of grafting, and I learned tons. It was more that, in the way of people who are really good at what they do, and have been doing it forever, Bill didn’t always seem to have the words to explain what he did in the most cohesive, organized way.
Despite leaving me feeling a bit lost during the lecture, Bill was obviously very, very knowledgable about grafting and budding, and some of the examples he showed of his work left me a bit slack jawed. For example, there’s this thing called bark grafting, where you basically stick a few little twigs under the bark of a big, headed-back branch. The twigs then take hold and grow into big healthy branches. It didn’t look like it could possibly work, but it did and Bill had the pictures to prove it.
Thankfully, my mild confusion cleared right up once we got to the hands-on section of the class. I pushed my way to the front of the table (sorry 90 year old lady with the priceless heirloom apple you were hoping to graft in order to preserve a family legacy) and my rootstock + scion (the scion is the part of the tree that actually grows the fruit) components became the “example” tree that Bill grafted.
I’m pretty sure Bill’s graft will take and my little apple tree will grow. While he was working, I stood right next to him and never took my eyes off what he was doing, so now I have a pretty good idea how to do a simple splice graft.
But I’m getting ahead of myself. Here’s what I learned (and keep in mind my experience with grafting is a single 90 minute seminar, so if you really know your grafting stuff feel free to expand/correct/dispute my summary).
With any grafted tree, there are potentially three components you’ll be dealing with. From top to bottom they are: the scion (the wood that makes leaves, flowers and/or fruit), the interstem or interstock (the trunck or wood between the roots and scion), and the understock or rootstock (the roots). Grafting is attaching a scion of one tree to the rootstock of another. Sometimes you want the roots of one tree, the interstem of another, and the scion of a third tree. If that sounds like a Frankentree, don’t worry – it’s pretty common with ornamental weeping trees, like weeping cherries or weeping plums. It’s also a common way to graft fruit trees that grow multiple varieties of fruit, like 3-in-1 apples or “fruit cocktail” trees.
There are more ways to graft than I ever would have imagined, but they all work by aligning the vasular cambium of the scion with the cambium of the interstem or understock. The vascular cambium is a very narrow layer of wood just under the bark that carries all the nutrients and hormonal messengers of the tree. It’s sort of like the vascular system and nervous system in animals, all rolled into one super thin layer of cells. When you prune a tree or shrub and there’s a thin layer of green between the bark and the hard center wood, that layer of green is the cambium. Since that’s the actual living part of a tree, the part that transports nutrients, it is critical in grafting to line the two cambium layers up.
So at this point you are probably saying, “And this is exactly why I was a liberal arts major in college. I’m not a hard science person, and even if I was, why would anyone go to the trouble of doing this when they could just plant a seed and wait?” I’m glad you asked.
You graft fruit trees because most fruit will not come true to seed. A seed from a fuji apple, if planted, will not grow into a tree that gives fuji apples. Apples reproduce sexually (this would be the “flowers and bees” portion of the “birds and the bees” talk I hope your parents gave you at some point), so expecting an apple offspring to be identical to either of its parent trees is about as silly as expecting your kid to be identical to you or your spouse. I joke that my son is a mini-version of my husband, but he’s clearly not a clone, and thank goodness. But in the case of apples, we want clone trees, and we can make them by grafting. The scion wood grafted onto the rootstock will give the same fruit as the tree it was cut from, and in this way we ensure the tree will grow Fuji Apples instead of Crap-Hard-Worthless-Crabapples.
We also graft because different rootstocks have different advantages and disadvantages. If you garden in a wet area (like, say, the Pacific Northwest) you can graft your desired scion onto a rootstock that won’t drown over a wet winter.You can also select vigorous, aggressive rootstocks that will anchor your tree like crazy and give you giant trees that are near impossible to maintain, or dinky little rootstocks that require irrigation and staking so they can support a full crop of apples but will never grow a tree more than 6 or 8 feet tall and so are easy to pick, spray, and prune.
There are many types of grafts, and I learned the easiest, most basic: the splice graft. In the splice, you cut an accute angle cut through the scion and make a matching cut through the understock. You line those two cuts up, make sure the cambium is aligned, and tie the two pieces together. You hold moisture in with special plastic tape or wound sealer, and then cross your fingers. There’s an art to getting the two cuts perfectly matched, and you need a very, very sharp grafting knife (this is what Bill sold me at the class, cause I came totally unprepared) but it’s not really hard at all.
I grafted two types of apples today at Sky: a Karmijn de Sonnaville and a Rubinette. Both were grafted onto Bud-9 dwarfing rootstock, which should give me trees about 8 feet tall or a good base for an espalier. When I got home I got so excited about my newfound skills I dug up the suckering rootstock on my combo pear, and cut scions from last years new wood, and attempted to graft them together. If all take, I should have 6 baby anjou pear trees. My impromptu rootstock was very poorly rooted, and in many cases was showing only 2 or 3 little rootlets, so there is a good chance they will all die. But it was good experience and fun to do. And hey, if it works, pears for everybody!
Here’s some great resources if you are interested in learning more about fruit tree grafting:
Raintree Nursery Catalog: browsing through the Raintree Catalog is true orchard porn. Hours spent reading it cover to cover sparked my interest in fruit tree grafting. There is good basic info on rootstock varieties, ultimate size expectations, etc. It’s also a good intro to what trees are grown on what rootstocks in the Pacific Northwest. They sell rootstock and grafting supplies. And if this is all just more than you want to dig into, they sell a huge range of edibles, most of which will thrive in the Pacific Northwest.
The Grafters Handbook by R.J. Garner: This was the most recommended book at the Sky seminar. I do not have it, but Bill Davis said it was the best. It looks like it’s out of print, and used copies are pretty spendy on Amazon, so I’d definitely check the library for this one.
MU Extension Guide to Grafting: a 7 page overview of basic grafting techniques. Good pictures demonstrate several different techniques.
MU Extension Guide to Budding: Budding is similar to grafting, but you are only working with a single scion bud instead of a short branch. It’s the technique used with peaches and nectarines, and when work needs to be done in late summer. We didn’t learn much about it, but it sounds slightly more complicated than basic grafting.
Penn State College of Agriculture Guide to Grafting and Propagating Fruit Trees: 12 page .pdf that covers similar material to the MU Extension Guides and also talks about seed propagation. Good photos.