Species Diversity in a Limited Space
As permaculture designers, we are often faced with the problem of reconciling a client’s plantable space with their plant diversity wish list. It's exciting to imagine your yard filled with a diverse variety of fruiting plants, and when trees are young, you can certainly fit a lot of them in small spaces. In a few years’ time, though, you will have a problem, and so will all that lovely vegetation you planted. Some will struggle to produce, some will need to come out, some will lose out to the competition or succumb to disease problems exacerbated by poor environment. We have a few ways we'd like to share that can help reconcile your species wish list with your available planting space. They are:
2. Dwarfing rootstock
3. Pruning strategy
4. Container planting
5. Leverage neighboring trees
7. Structure: columnar, espalier, etc.
Did you know that there are varieties of apple and pear that don't need a pollinating partner? They are partially self-fertile and can fruit on their own, though the yield will be greater with a partner. There are, in fact, varieties of asian pear, like Shinseki, that can overproduce with a partner. Apricot, Yuzu, Fig, Mulberry, Loquat, Medlar, Nectarine, Peach, Sour Cherry, Pear and Olive all exhibit partial or full self-fertility. Self-fertile apples include Granny Smith and Braeburn. See a complete list here. Bartlett is partially self-fertile and Flemish Beauty is self-fertile. There are many more.
Dwarfing rootstock is a great strategy. For apples, we use Bud-9 and M27 to keep the tree's vigor to around 6 - 8 feet in height. You can thus reduce spacing with smaller trees, of course, and dwarfing rootstocks are readily available online if not from your local nursery. Do select the appropriate rootstock for your local ecology.
Ever see a bonsai? While it requires some work, you can keep a tree’s size down through pruning. You will want to begin the structural pruning early in a tree's life and not massacre an adult tree into submission: small changes over time, as the proverb goes.
We've designed mobile apple orchards in containers. You can do this too. It's important to select a dwarfing rootstock for container planting. The tree will fruit and won't outgrow the container. It won't have the life expectancy of an open planted tree, but many of us won't be around to notice. Container planted vegetation is prone to drying out, so you will need to ensure this doesn’t happen with a close eye or an automated irrigation solution.
Use your neighbor's trees...and you don’t even need their permission! If you have identified a neighbor that has, for example, some pear trees, plant your single pear tree as close as possible to theirs. Inside 25 feet is ideal but 50’ is probably okay too. You will be using their tree(s) as pollinating partners.
Big one here: if you want apple variety with limited space, graft multiple varieties onto one rootstock. You can collect scion from anyone willing to share. There are also several groups that host scion exchanges. Grafting is not complicated. If I can do it, so can you.
Structural Control of Trees
Columnar style trees won't branch out with laterals. They fruit off a single leader, so to speak, with a compact growth habit. They grow about 8 feet tall. We use these quite a bit. I like the Ultra Spire variety, but there are many to choose from. Use cordon or espalier to grow against a wall. You can actually buy these pre-trained or do it yourself.