A few years ago my friends started up a blog over at Far Out Flora, and asked me to write a guest post. I was totally honored, and for some reason totally scared to write for a blog. I put together an idea of what I wanted to write about, but just never got it together to do the actual post. The thought of the post stayed with me, and eventually their inspiration led me to start my own blog here. Though I never did write that guest post for them, I figured I might as well finally write what I was planning to oh-so long ago.
“So Long, Suckers” is not a post about Matti and Megan moving to Wisconsin. 🙂 (Congrats on your baby girl, you two!) Suckers are actually those little shoots that come off a plant’s roots or right at the base of the trunk of a tree. There are other types of growth that also get called suckers, such as water sprouts, but the general connotation is that the sucker is growth that inhibits what you are wanting to grow. You generally encounter them on trees, but you’ll also be aware of them on roses and on many other types of plants. Seems the rose family, Rosaceae, which also includes apples and pears and plums, is a super-prime candidate for suckers. They are very much a natural part of plant growth, so what’s so bad about them?
When it comes down to it, nothing really. In ornamental gardening, though, they can be a nuisance. We do a lot to plants in the nursery industry to make them what we want, and they require maintenance to remain what we intended. Suckers can slow plant growth, or even be a different plant altogether!
Let’s talk basal suckers (the ones at the base of a tree.) True suckers, if you will. I see it a lot with street trees, especially with SF’s proliferation of Ginkgo and flowering cherry and plum trees. Many trees naturally form something of a thicket – many trunks will sprout from a single base, like in plum trees, and if left untended you’ll eventually have a dozen or more trees from one spot. None will develop thicker than a few inches of trunk, and all will stay about 10-12 feet high.
What does suckering do? Well, let’s think about it: each plant has a network of roots to support and feed it. If you have a tree, its roots are doing just that. Add a sucker or a dozen suckers, and that same root system is now having to support a dozen trees. Naturally, they will be limited in size. This works just fine in nature – it’s how the plants were designed. But here we are with a tiny little SF back yard, and we don’t want a thicket of a dozen plum trees taking up the whole yard. Or we have a street tree in a 2×2 square cutout of sidewalk and need it to be a clean look. It’s messy and offers a haven for rats and other critters you may not want out there. We just want one plum tree. By removing the suckers, all that energy that would have come off the roots to support the thicket now gets redirected into the remaining solitary tree. The tree gets thicker and taller than if left to its own devices, because there is only one plant to support. Keeping the suckers cleared allows the tree to spread out a canopy of shade instead of being a cluster of vertical growth.
There’s another reason to snip off those suckers: It could well be a plant you don’t want! Grafting is phenomenally common in nursery stock, in particular with fruit trees and Japanese maples. Grafting is the practice of taking a cutting from one plant (called the scion) and splicing it onto a different species of plant (the rootstock – the one that will provide the roots for the cutting). Fun things can be done with grafting, including creating a small apple tree with six branches each bearing a different kind of apple! Many ornamental trees (like the ornamental flowering plum and cherry trees that provide no fruit) can only be multiplied by grafting, because no fruit means no seeds. Some seed-producing plants get grafted because they were a cross between two other plants, and the seeds will grow into one of those grandparent plants instead of being another of the same plant you collected seed from. One of the more common reasons for grafting is to control size and provide good roots. By grafting a cutting of a large species of lemon onto the roots of a small species of orange tree, for example, you thus end up with a root system that will limit how big the lemon can get, resulting in a dwarf tree for a small yard or patio.
That’s where killing off those suckers is most important. You bought a dwarf lemon tree, and I assume you want a dwarf lemon tree out of it. If a sprout is coming off the base of the trunk, it’s coming from below that graft union. That sucker is going to end up being an orange tree. The sucker is coming off it’s own root species, so the roots will favor it over your scion lemon. If you let the sucker grow, it will outpace your lemon. Your lemon will fail eventually. And someplace like here in SF, that would mean a useless fruit tree, since we don’t have the heat to make oranges grow anyway. I did this with a rose sucker once. It was supposed to be a ‘Barbra Streisand’ with lovely lavender petals. This strong new shoot came up so I ignorantly cut off the seemingly weak trunk, excited that she was growing stronger now. It was, of course, some species whitish rose, and not my Babs.
Or it could be color. Those beautiful red-leaved flowering plum trees around town (Prunus cerasifera ‘Atropurpurea‘) are scions grafted onto some regular ol’ plum tree. Let the suckers go, and you’ll find lots of green plum leaves coming in, and untended they will smother out your purple leaves! Naturally, the roots want to support what they were designed for. It’s our own intervention that is making them support a foster tree, and it’s our responsibility to maintain the foster or they will overpower it.
I mentioned water sprouts earlier. Those are the vertical shoots you get on some trees, like the red-leaf plums. In small back yards and with street trees, you really want to treat those like suckers, too. All that vertical growth will only add significant weight as they thicken and multiply. The tree will get weaker and eventually come crashing down. You want to keep those cleared so you can focus on the actual branches and structure of the tree.
So let’s keep those trees sucka free!