Sooner or later every gardener meets a potbound plant. Constantly growing but without access to the outside world, the roots of container-grown plants try valiantly to escape through the drainage holes! But, alas, they can only circle endlessly, traveling to nowhere and eventually forming a nearly impenetrable casing on the rootball. Good stuff like water and fertilizer can’t really get in and, more important, new roots can’t get out. Uncorrected, the roots may never get out of their prison, and the plant will eventually die.
Roots aren’t able to alter a circling growth pattern on their own, so it’s up to the gardener to loosen them. Keep in mind that any damage you cause in liberating your plant will heal and is outweighed by the down side of doing nothing. Only the outer roots need to be loosened; leave the core of the root mass alone. There are two approaches to loosening the roots, teasing for lightly rootbound plants or cutting for heavily rootbound plants.
For lightly rootbound plants, TEASE roots out of their circling pattern. You can usually use your fingers to gently tug roots outward working from the tips back towards the root mass. Sometimes, especially for annuals, you can simply pinch off matted roots. And sometimes a three-tined garden claw works better than fingers. As you backfill with soil, try to splay the roots outward horizontally in the planting hole .
For heavily rootbound plants, you have to CUT roots to stop their circling. The top six signs of a heavily rootbound plant? 1) Lots of roots are coming out of the drainage holes — that’s an easy one. 2) You think you might need a crowbar to pry it out of the pot. Don’t. Slice the pot instead. 3) Your hands stay suspiciously clean when you do get the plant out of the pot because there’s barely any soil left. 4) The root mass sounds like a ripe melon when you thump on it. 5) The rootmass looks like a doormat. 6) You think you might hurt yourself if you poke your fingers into it. Seriously.
Teasing these roots will NOT work. It probably won’t even annoy them, and it certainly won’t make them change their behavior.
So, make vertical cuts or slices about 3″ to 4″ apart and deep enough, about 2″, to sever the circling roots. Use clean, sharp tools. Or you can slice off 1/2 to 1-1/2″ thick slabs of the matted roots all the way around the sides and bottom, similar to removing the crust from a loaf of bread. Everyone at the nursery laughs when I say I actually use an old breadknife for this — but it works great!
Weston Nurseries, Inc.
katbergmann
waynemezitt
Melissa
Ann W
I never thought of the bread-crust approach — great tip! I’m also going to use it on plants i want to keep in the same size pot. I use the butterfly approach to my S&M-loving potbound plants like rhododendrons but it just seemed wrong for a lot of others. One question, though: if it’s a fleshy-rooted plant that’s sensitive to assault, like a magnolia, what would you do?
Excellent question. This is a cost-benefit judgment call. Circling roots will continue to circle unless realigned or removed. If at all possible, tease out the roots from the rootball of a container grown magnolia. If, however, the roots are hopelessley matted from circling the inside of the pot, they will have to be cut. In this case the goal should be to make clean cuts with a clean tool to optimize quick healing. And follow up by giving the plant the resources it needs to settle in well — a starter fertlizer in the backfill and regular, deep waterings.
Very helpful — thanks!