I'm a newbie looking to introduce several trees to my small home garden located in Zone 6, just north of Boston. Space is limited so I want to restrict the size of the trees to make harvests easier, save open space for annual vegetables, and be able to harvest fruit as many days of the year as possible. Also some fruits I am interested in require an additional tree for pollination. I've reigned in my impulse to "just buy some trees" until I better understand what I'm doing.
My research thus far has led me to believe that there are at least a handful of methods to keep size down:
- A. Find trees I want grafted onto dwarf rootstock
- B. Use pruning alone to limit/control growth
- C. Limit root system growth with above ground containers
- D. Limit roots with in-ground semi-permeable containers (e.g. "root control bag")
- E. Plant trees closer together to compete for resources above & below ground
- F. Insert something else here
- G. Some combination of the above.
I presume a certain amount of pruning will be required to promote healthy airflow regardless of what/where I plant. However it's unclear what the pros & cons of the various dwarfing methods are. Is there impact on disease resistance? Does it affect the longevity of tree? Do rootstocks affect flavor or nutrient requirements? Specific trees of interest for me are Apple, Peach, and Plum and I'm also considering Fig, Persimmon, and Pawpaw. I'd also consider Almond and Pecan if they can be kept to a limited size.
You can also effectively reduce the size of a tree by grafting multiple varieties of the same fruit to one larger tree. For instance you pick your apple varieties and instead of growing a separate tree for each you have all of them on one larger tree. I'd guess that if you put 4 varieties of apples on one semi-full tree (M111 rootstock) you'd take up less space and make the trimming easier. Mowing around one tree is simpler than mowing around several. I'd say that you might get more fruit off a semi-full tree with 4 apple varieties than you'd get off 4 dwarfs.
A full size peach is about the size of a semi-dwarf apple tree. I bought two peach trees. One a semi-dwarf, the other a full size peach. The semi=dwarf is 3 years old, produced 10 smallish peaches this year. The full size tree is 2 years old and produced about a hundred peaches this year. We made a pie, froze enough for 3 more pies and canned 6 pints. After the harvest I trimmed the big trees top growth to about 8 feet high. The semi=dwarf is about the same heighth, but I didn't trim it as I'm not so afraid of it getting away on me.
Grafted trees are the normal method to get small trees for limited space, these can be bought already grafted to dwarf root stock or you can buy dwarf root stock and graft your own.
Pruning alone will limit top growth to a point but it will also create weak branches at some point, which translates into damaged trees from wind broken limbs.
Trees grown in containers need to be considered Bonsai, you will be lifting and pruning both top and bottom at least bi-yearly to keep the tree in the same container, moving to larger containers will slow growth but it also means heavier and heavier containers (which aren't inexpensive).
The above goes for root control bags too.
Crowding trees is asking for disaster from disease and or insect pests, the closer trees are the easier it is for a disease or pest infestation to spread to the whole orchard.
these are the cons, if you are looking to reduce your time spent tending the trees, grafted dwarf or semi-dwarf trees are probably the best choice since they can be in ground and will need little attention once established (compared to container trees or in ground pruning).
More trees are killed every year by root control bags used as if they were containers for an orchard, people forget they have to water these trees just as if they were in a container above ground or in a nursery (the setting they were developed for).
Crowding (intense planting) can see all trees decimated by any of the blights or other diseases faster than you can get it under control, it can also lead to reduced fruit production of all trees.
On the plus side, it can make it easier for pollinators and that can mean a great fruit set, but then you have to go in and thin the fruit to protect the branches and if the crowding is thick enough, that can be very hard to maneuver in the orchard.
In such a situation, where I had limited space and wanted the most variety of fruits, I would look at devising a planting scheme that made full advantage of dwarf trees (these can usually be within 10 feet of each other with just a little pruning necessary to prevent tree overlaps).