My grandparents had an apple tree growing in their back yard. It was probably 30 feet tall with an equal spread. To 10-year-old me, it seemed huge. They yelled at us when we climbed in the tree and told us the apples would make us sick so don’t eat them. They didn’t tend to the tree or harvest the apples. It was just a shade tree they had to clean up after in the fall. So, it was a nuisance in the fall, but it provided cool shade in the summer when there wasn’t air conditioning in every house.
A friend of mine has a 100-year-old farm house with three apple trees in the backyard. He tends the trees religiously, harvests the apples, and makes cider every fall. The trees are 25 to 30 feet tall. To prune the tree or harvest the apples, he takes a long extension ladder and just leans it against branches. Then he climbs the ladder, and it sinks into the branches until there is enough tension to keep the ladder from falling over. He hopes. He has done it enough years, that he doesn’t worry about the possibility of falling down and crippling himself. Still, it’s a tremendous amount of work and a tremendous amount of risk to prune it, spray it, and harvest the apples every year.
And if you want apples, you will prune it. Apples grow on a two-year cycle. Sunlight that falls on branches this year grows the spurs this year, that will produce blooms and apples next year. Then, the apples need direct sunlight to ripen properly. So, the primary purpose of pruning is to open up the tree so that sunlight penetrates into the tree to all the branches and all the spurs and all the apples. Otherwise, you only grow apples on the outer branches on the southern side of the tree. Then you have lots of “tree” producing useless green growth everywhere else and no apples. And, you need your spray to penetrate into all those branches growing all those apples or you get fungal infections, bacterial infections, and insect damage on the tree and the apples.
If you do your job right, your full-sized tree will produce upwards of 20 bushels (800 pounds) of apples each year. If you don’t live close to someone that also has an apple tree (of a different cultivar), then you have to plant a second tree to be a pollination partner (we’ll talk about cross pollination another day). So now you have two full-sized trees to climb into and prune and spray and pick the apples. Then you’ll have 40 bushels (1,600 pounds) of apples each year to deal with (and you thought getting rid of extra zucchini was a challenge).
But what if you don’t want half a ton of apples every year. What do you do, if you only want a few bushels of fresh apples each year? The answer is to plant apples trees that are grafted onto dwarfing rootstock. The rootstock acts as a skinny straw that limits how much water and nutrients the tree can draw from the ground. This prevents the tree from growing to its full potential. Depending upon the rootstock, the resulting tree will be anywhere from 4 ft tall (very dwarfing) to 16 ft tall (semi-vigorous).
The most common modern dwarfing rootstocks were developed in the early 1900s in England and are identified by the prefix M (Malling) and MM (Malling-Merton). Other important varieties were developed in the late 1900s at the Geneva facilities at Cornell University in New York. These are identified by the prefix G (Geneva).
Apple trees grafted on to dwarfing rootstocks can be planted in small yards and can be managed (pruned, sprayed, and picked) from the ground or a short step ladder. Several trees can be grown in the space that a single full-sized tree requires. This means that multiple cultivars can be grown in a limited area to ensure the trees have pollination partners. On the down side, dwarfing rootstocks tend to produce small root systems. Under a heavy load of apples, the trees can actually uproot and fall over. So many varieties of dwarfing rootstocks require the tree to be permanently attached to wooden or metal posts to support the tree.
Even apple trees grown on dwarf root stock require diligent pruning to ensure that sunlight can penetrate to the center of the tree to keep production high and to allow spray to reach all parts of the tree. The example above, shows dense green growth which has no real value and just gets in the way. These trees, while relatively easy to manage, are still fairly inefficient at growing apples. And that’s what we want right? We want apples not trees.
If you just want a pretty shade tree to fill in a spot in your yard, then buy a shade tree. If you want to grow apples, (or pears, or peaches, or whatever), you need to prune the tree to grow as many apples as possible in the space that you have at your disposal. And then you want to grow just enough leaves to keep the tree healthy and happy while ripening the fruit.
Spindle Trees – Violating Social Distancing Rules
These orchards are planted on semi-dwarfing rootstock which will allow the trees to grow about 10 feet tall so the trees can be managed from a tall step ladder. The trees are planted very close together (2 to 4 feet apart), and are arranged in rows with wire trellises providing support. The rows are far enough apart for a tractor to drive between the rows. The trees are pruned to give many short, stubby branches were all the apples will grow. There is very little green growth on the trees.
If the rows are arranged heading north and south, then both sides of the row of trees will receive full sunlight as the sun traverses the sky from dawn until dusk. This ensures that all the apples get lots of direct sunlight which is necessary for proper ripening.
The same technique can be used in the backyard orchard. Using dwarfing rootstock (which produces a 6- to 9-foot-tall tree) trees can be planted in the ground a few feet apart and tied to a permanent stake for support. Using very-dwarfing rootstock (which produces a 4- to 6-foot-tall tree) trees can be planted in pots and moved around for to where ever is most convenient.
Isn’t modern horticultural science wonderful. Growing trees that don’t look like trees in confined spaces to provide fresh fruit in your own backyard. No ladders required. Simple pruning tools. Basic garden sprayers. It’s truly amazing that no one ever thought this before. Like ever. Or even in the last 500 years or so.
Espalier – Getting Medieval On Your Trees
So, you’re stuck in the castle. The enemy is digging trenches and getting ready for a long siege. You did the best you could at gathering up the crops, and you’re fairly well stocked on grain. This means that bread and beer are your basic sustenance for the foreseeable future. Still, a nice apple tart would be a great way to brighten up the day. Good thing you planted some apple trees in the courtyard.
To conserve space, you planted the trees right next to a stone wall. You pruned away anything that isn’t directly next to the wall. And you tied the remaining branches to a trellis that is mounted on the wall. Now you didn’t just pick any wall. This wall faces south. So, the wall absorbs heat all day from the sunlight and then radiates that heat back out at night. The benefit of this is that it keeps your blossoms from freezing if there is a late frost in the spring or keeps your apples from freezing if there is an early frost in the fall. You care about this because you are in the middle of the little ice age in northern Europe. Without that wall, the growing season is just too damn short some years.
Not only does it work, it works really well. The trees produce more fruit per foot of branch that a regular tree does; the fruit is larger; and the fruit is higher quality. When the siege finally ends, you decide to try this out in the orchard. After getting the trees established on trellises you find that you get more bushels of apples per acre that you do from traditional, full-sized apple trees. This is great, but the infrastructure costs (trellises) is really just too high to justify redoing all the orchard.
However, one of the peasants that work your fields figures out how to plant trees close together; grow the branches at an upward angle; and then weave the branches from adjacent trees into a basketweave of sorts. These trees become self-supporting and do not require a trellis. When planted in long rows, the trees become living fences separating fields from each other and from roads. And these fences produce high-quality fruit.
Planning Before Planting
Now you’ve seen the new ways and the old ways of managing apple trees to optimize the production of high-quality fruit in confined spaces. Yet there is still much to decide before planting your first tree. Many considerations go into choosing which cultivars (varieties) to plant based upon plant hardiness zone; flowering group; disease resistance; and what you want the apples for — eating, cooking, backing, and juicing.