Pruning, planting density, yields, and longevity

Hello,

I'm interested in maximizing what fruit trees I can plant with an urban lot that is not exactly huge, size-wise. I've been watching videos such as Geoff Lawton's Urban Permaculture video and this one from Dave Wilson Nursery on backyard fruit tree basics.

In both videos, there are references to ?relatively aggressive? pruning of fruit trees to maximize diversity for small scale growers amongst other goals. As an aside, I seem to have come across many individuals who have commented on this topic to say just prune a tree to the size you want to maintain it, rather than purchasing dwarf or semi-dwarf trees.

What I'm interested to know is if anyone can share their experience with such techniques.

I'm particularly interested in:
1. How much spacing requirements can be reduced between fruit trees when pruning is done this way from a seedling size onward? Say you prune a semi-dwarf cherry tree to 10' height and width, rather than the 15' it says it grow to be and the 15' spacing it needs, will the spacial requirements below the surface be altered? How far can this be pushed?
2. With that said, is it possible one could 'over-prune' to the point where trees weren't giving that great of a fruitset?
3. How drastically will this effect yields?
4. How does this effect the longevity of the tree? Has anyone had noticeable reductions or increases in lifespan when this is done?


I understand pragmatically there obviously needs to be room for a human to maintain and harvest from a tree and they have requirements for sun. Appreciative for any perspective shared.

Bump. I really would like to hear answers to Jp's questions

These are good questions. Hopefully we generate some good discussion around this topic.

As for size and planting distances, it would pretty much depend on how much pruning you do since the root system will tend to be proportional to the top growth. I'm sure there are limits, but I think for a lot of trees, they would be pretty extreme, mostly coming into play in container style gardens.

As for maximum fruit production per unit of area, I would definitely like to see some comments on that. I suspect by eliminating tall growth, production per unit of area would be limited somewhat, but there might be other factors in play that would make up for the loss of vertical growing area. In particular, given their shallow roots, it might turn out that with fruit trees, root mass is more of a limiting factor than catching sun, in which case the short trees, planted densely, might produce better per unit of ground area.

This is something I am very interested in doing, but don't have personal experience with yet.

I've read heavy pruning in summer can make some trees fruit sooner. Winter pruning means more growth and summer pruning means more/earlier fruiting, is what I've read. That aside, some kinds produce fruit on the tips only so with those you'd have to thin branches rather than cut everything back.

You would want more horizontal branches, as well, rather than vertical ones, because horizontal branches are "fruitier". I think in a small space even 10 feet high is too much. You want the branches down where you can easily reach them. Training them to a trellis/wall is probably the best use of space, or a cordon or tilted cordon "hedge". Training them to odd shapes will mean they may need support to keep them from being blown over. Also, with a standard size rootstock rather than a dwarfing one you'll have more vigorous growth so it will keep you busy keeping the trees to the size you want, but standard roots are also hardier and make the tree more resistant to disease and drought.

I planted pear and shipova trees too close together. The amount of pruning necessary to keep them in a reasonable size became really time-consuming but they did start to bear fruit in just a few years. In summer you need to start early or the leaves will get so thick it's hard to see what you're doing. You'll want to think about what you want to do with all those sticks too. Chop and drop is nice if you don't start getting weeds growing through them, then the sticks make it really hard to get up the weeds. I had problems with burdock and bindweed. A little burdock is nice but too much and it really gets out of control.

The closer the trees are, the more they will compete for the nutrients in the soil. It is supposed to slow their growth a bit, but pruning would still be necessary. I would chop and drop what you take off of the trees (unless you are using for some for scionwood) to help return the nutrients they have taken up back to the soil. Pruning will also limit fruiting some. You should also be thinning the fruit on what is left. The fruit you produce should be larger and higher quality since the tree is putting it's energy into less fruits.

You might also want to consider planting nitrogen fixing trees/bushes to help support the whole system. I would think that planting a more dense system would make the system "hungrier". You can also chop and drop the nitrogen fixing trees/bushes to keep them at reasonable sizes. Heck, plant nitrogen fixing that fruit and it would be a double benefit!

There are things like nut trees which would not do well being pruned. If you are thinking of them, I would go with the bush versions (hazels/filberts and chinkapin) which can be pruned to maintain a controlled size. I think, if I remember correctly, almonds can be a controlled size too, or you could even graft them onto your plum/peach/nectarine/apricot stock.

A few data points from apples:

Traditional spacing on MM111 (semi-dwarf) rootstock is around 15x20. One of the major English cider makers (Bulmers?) is now growing them on 6x20 spacing, in anticipation of mechanical picking. So you can push them quite close. I know that some of the cider growers are trellising even semi-dwarf trees on very tight spacing. That adds initial expense but in humid environments it may pay off with better ventilation to keep back the fungal pests. Apples need hard thinning to produce quality table fruit. So keeping the branching structure smaller could naturally reduce the amount of initial fruit set on the rootstock.

Apples put on the following year's fruiting wood in late spring. Summer pruning would destroy the next year's fruit yield.

But why fight the inclinations of the tree? There are plenty of great trees on offer on dwarfing rootstock that will take way less work to keep it manageable. And precocity is not going to be different for a semi-dwarf regardless of how it gets pruned in year 4 or 5 to control ultimate size. By then you'd already have had fruit on a B9 or M7 or G11 rootstock. I may be swimming upstream from some of the permie crowd here, but humans have been grafting trees since Roman times. I have so many types of rootstocks in my orchard that the state pomologist thinks I'm nuts. I did it just because no one has tried them here. The interstem grafts are really interesting--a semi-dwarf on the bottom for anchorage and disease resistance, an intermediate rootstock for dwarfing and precocity, and then the scionwood. These trees are doing beautifully for us.

In a small yard, the limiting factor may in fact be getting enough varieties for effective cross-pollination. You'll need at least two carefully selected apples. Even things like peaches that are supposed to be self-fertile will do better with a nearby cross-pollinator. We plopped 3 plums into a clump, could have even put them in one hole, will let them grow more like a bush. Maybe taking up espaliering would be a good hobby! You could definitely exploit edges that way. Probably the only way to really control a pear, even on a smaller rootstock.

Do you want a tree that will outlive you, but needs a heavy hand with the pruners every year? Or do you even plan to live there that long? Fashions in fruit change (who even heard of Fuji apples twenty years ago?) so replacing a dwarf tree every couple decades might not be a big deal. Peaches don't stay at top productivity even that long and SHOULD be replaced every 15 years or so. You could plan for succession planting every decade if you select smaller trees and leave some space.

Personally, I don't want a bonsai project-I let the rootstock do that work. Life is too short to fight a tree.

Could there be a big advantage to "fighting the tree" if the trees are stronger? I heard somewhere that dwarf trees are just genetic runts; that's why they are dwarf. Is this correct?

Jp Learn wrote:1. How much spacing requirements can be reduced between fruit trees when pruning is done this way from a seedling size onward?

I have a pretty small space and most of my trees are espaliered. It's a very productive system, which is very simple to manage.
I go for semi-dwarfing rootstock. The trees (and root systems) are still reasonably large, but not as vigorous as a 'full size' tree.
I don't use full dwarfs, either 'natural' or grafted: they have very small, weak root systems and require staking forever

Jp Learn wrote:2. is it possible one could 'over-prune' to the point where trees weren't giving that great of a fruitset?

Absolutely. Different species have very different fruiting habits. New wood, old wood...it's a bit mindboggling actually!

Jp Learn wrote:3. How drastically will this effect yields?

Very drastically, I think, if different species of trees aren't pruned to their growth/fruiting habits.

Jp Learn wrote:4. How does this effect the longevity of the tree? Has anyone had noticeable reductions or increases in lifespan when this is done?

That I don't know, although I understand young wood is much more productive,
so I'd take a guess that regularly pruning out old wood increases the tree's productivity. Whether the increased productivity reduces the tree's lifespan, I have no idea!

As Ann says, do plenty of research about varieties before you buy anything to make sure they're compatible.
I'm a big fan of multiple grafting and other nifty tricks: pears must be cross-pollinated, and a full-sized tree is anormous.
I have a double-grafted, espaliered pear on dwarfing quince rootstock that had its first pears this season

The database at Orangepippin.com is as good as any I know for data on table apple bloom times, cross-pollination, etc.
They divide apples into 7 flowering groups, for example, and stuff that is in the same group or pretty close "should" bloom at the same time for cross-pollination.
Triploids, like the Jonagold are poor pollinators, so if you want that variety, you need to plant 3 trees: 1 to pollinate the Jonagold and one to pollinate the pollinator.

They also have sections on plums and cherries, which I have not used.

A pretty decent list of the pros and cons of the common apple rootstocks at thenewfruitgrower.com. Don't buy a tree labeled "semi-dwarf" because that could be any one of a half dozen rootstocks. If they don't know which one and why it's right, shop elsewhere.

Cider apple data is hard to find.

If a 20ft tree produce 40lbs of fruit, a 10ft tree normally produces 20lbs of fruit. So the height/yield is directly proportional.
You have to careful with your pruning so that it doesn't produce too much waterspouts, which are all vegetative and none fruiting
Try to keep the angle of the branches between 60 and 90 degree.

Pruning a tree to 10ft will reduce the spacing to 10ft too.
Pruning your trees will reduce their lifespan. a 10ft tree will probably only be productive for 20yrs

I recommend getting dwarf or mini-dwarf fruit tree

Ann Torrence wrote:The database at Orangepippin.com is as good as any I know for data on table apple bloom times, cross-pollination, etc.

I actually looked it up to put in here, then forgot
Thanks Ann, it's my favourite apple site!

If my garden wasn't already full, I would get a few plants from these guys tell me what you think of them

http://pacificgroves.com/patio.html

S Bengi wrote:If my garden wasn't already full, I would get a few plants from these guys tell me what you think of them

http://pacificgroves.com/patio.html

Very cute! Probably on M27 rootstock. There's nothing magic about where you start the branching, they should fruit just fine. If I weren't overloaded with apples already, I'd put in some English step-over apples. I might do some anyway, just for the novelty factor. I remember a photo in one of Rosemary Veery's books of step-overs and it was so pretty when they were in bloom.