Aconitum napellus


A couple of weeks ago, I engaged in yet another epic struggle with tree roots.

A perennial bed that was root-free when first planted (about twelve years ago) had been showing signs of decline for several years. Plants were smaller and obviously struggling, especially the hostas. Turns out hostas don’t compete well in rooty situations; strange, considering at least some species are native to woodlands. Not woodlands of Norway maples, I suppose.

I’m pretty philosophical about the older beds in the back garden. After all, they are close to five large trees, three of them maples (1 red, 2 Norway), whose roots interlace in a network throughout that 50 by 50 foot space. Goodbye, vegetable patch. Tough plants only. But this newer bed, situated in a narrow strip of land between my house and my neighbours’, was, I thought, far enough from any tree to remain root-free. The drip-line (canopy edge) of the closest maple was safely distant, and tree roots don’t extend beyond the drip-line. Or do they?

Yes, they do. Roots roam far and wide, as it turns out. Once I discovered creeping rootiness in that new bed, I started reading up on how tree roots grow. There was surprisingly little written for home gardeners, even those who are familiar with Latin plant names. I found a lot of scientific papers written by researchers in the fields of forestry or agriculture. Their focus was narrow and their terminology over my head.

Finally, I found this — relatively comprehensible and relevant to my situation. Also discouraging. The drip-line idea is one of the fallacies. Au contraire, “it is not uncommon to find trees with root systems having an area with a diameter one, two or more times the height of the tree.”


This isn’t how it works! (Image from Pixabay)

Trees send out long, questing roots that keep on growing as long as there’s a reward in the form of water or nutrients, as in a fed and watered perennial bed. The roots run along horizontally, sending up vertical subsidiary roots ending in fine mats of feeding roots. Those are the ones that make that typical ripping sound when a spade is thrust into the soil.

So I tried a strategic strike. I dug up a clump of purple monkshoods (Aconitum napellus) and a few young hellebores at the end of the bed closest to the tree I suspected to be responsible for the root. Then I excavated down two feet and indeed found not one, not two, but three roots a couple of inches apart, each of them about two inches in diameter. Using a nifty little saw (actually intended for cutting wallboard) and a hatchet, I removed sections of these roots, one to three feet in length. Then I dumped in some compost and replanted the aconites and other plants. Thanks to cool and rainy weather, they recovered nicely.
I hope this will give the perennials in the beleaguered bed a chance, if only for a season or two. I don’t relish the thought of a full-bore rebuilding of the entire bed in the grand manner. This rather limited effort was enough for an aging gardener.
October 20, 2011

Hostas, autumn of 2012.