Hi all,

I'd like to know if it is possible to graft new varieties of, let's say apples, onto an already grafted tree.

For example, if I were to buy a grafted dwarf Granny Smith apple tree, would it be possible to graft other apple varieties onto this same tree?

If yes, could it be grafted onto the Granny Smith portion of the tree, or would it have to be grafted to the root stock?

You would graft the new branches into the Granny Smith. Those added branches would most likely also be dwarf as its the rootstock that determines the size of the tree.

Multiple 'in line' grafts on the same tree is a known and proven practice. All parts must have compatible genetics, though. In general, apple to apple (or crabapple), pear to pear, etc. There are exceptions, however.

Thank you for your replies, Daisy and Rick!

What would you say is the upper limit to the number of different 'in line' grafts you would add? At the moment, I have three other varieties I'd like to grow besides, the Granny Smith, which ideally would all be on one tree. Would these all be feasible on one tree, or should I have two trees with two varieties on each?

Also, could you please elaborate about the exceptions?

If multiple grafts are 'in line', then they all are part of the same path (a single line) to the roots. Grafts 1 and 2 are always in line with other grafts, since there is no other way to the roots. Grafts 3, 4 and 5 are in line with 1 and 2. But grafts 3, 4 and 5 are not in line with each other.

Draw a single line from any graft through the tree to the roots. All the grafts that you connect with the line are in line.

Multiple grafts similar to what I show have been done successfully. Technically, there is no limit to the number of grafts. In the practical sense, no more than three or four in line grafts are done. Usually, it is just one.

For grafts that are in line, only one graft can be done at a time, usually on a yearly basis. Grafts that are not in line with each other, i.e. grafts 3, 4 and 5, could all be done at the same time. And yes, since 3, 4 and 5 are not in line, you can have several different kinds of apple on one apple tree.

Grafts are weak points of structural strength in the tree. You will want to be sure that grafts like 3, 4 and 5 are whip grafts. Grafting is a skill, so don't be discouraged if they don't take the first time. You will need to read up on it from a reputable source. FYI, 'in line' is my personal description for clarity. As far as I know, there is no universally used designation for such graft groupings.

Regarding exceptions:
In the natural world, the only unbroken rule is that there are no unbroken rules.
Mother nature is always experimenting and sometimes things work unexpectedly, and sometimes things don't work when we think they should.

Sometimes genetic matches must be very specific to be successful. Sometimes the match only needs to be more general. For example, we are all the same species (Homo sapiens), but to transplant (graft) an organ like a liver, the blood types must also be compatible. With plants, sometimes it needs to be very specific like this, but sometimes a match can be much more disparate.

In general, grafting a clone of a species onto that same species works. The two living parts are compatible. Often, closely related species in the same genus are compatible. Sometimes, more distantly related pairs can be grafted. Sometimes grafts seem initially successful, but eventually fail (usually in 1-5 years) due to incompatibility. Some kinds of plants graft pretty easily, like fruit trees. Some plants are difficult to graft, like oaks.

there shouldn't be any compatibility problems with apples, though.

Thank you so much for your help, Rick.

You've given me lots to think about.