Combating roots


Wondering if I should move all plants from this garden. I didn’t consider the root system of my cedar hedges when I started this garden a few years back. Now when I dig down even an inch, I am digging into fine roots which I can only assume are from my cedars. I have already moved an echinacea plant that was failing, but at the time I didn’t know why. I fear I will lose more plants if I leave them, but I’m not sure if I should just leave them alone and hope for the best, attempt to amend with more soil or just transplant everything. Here are the plants which names I can think of
Ohio Spiderwort, Crevice Alumroot, Astilbe, Redvein Dock, Columbine, butterfly bush and a couple of rose bushes. I transplanted most of those from my aunts garden when she passed away (I think she was actually a Master Gardener with your club – Irene), so I really don’t want to lose any of these plants. The location (south east) receives sun from about noon to days end. The soil in that corner prior to the installation of the cedars has always been quite dry, very hard, very few earth worms as there was a shed on that spot before we moved in back in 2013. The soil improved a bit when I first added the garden / amended the soil, but the roots have really overtaken the quality soil. The cedars were installed before the garden. I am in Scarborough. Any assistance you can offer would be greatly appreciated.


First, let me say for myself and for the rest of the Master Gardeners, thank you for wanting to honour Irene this way.

Second, you are correct, this small bed is a challenge. Those cedar roots are shallow and plentiful, as you have discovered. They will suck up all the available moisture and continue to expand and crowd your plants.

And because the bed is actually surrounded on two of its three sides, that network of tough roots will be especially complex.

You may have looked elsewhere online and discovered articles that recommend cutting away the roots when you plant. There are three problems with that response:

  1. Previously, we advised an inquirer that for every 2.5 cm of tree trunk diameter, you must avoid cutting roots 30 – 45  cm from the tree. I suspect your cedar trunks are more likely 5-7.5 cm in diameter, meaning you couldn’t cut roots any closer to them that 60 to 90 cm. That  would leave you with a very tiny space to  plant. There are many such “rules of thumb” as described in this article from the University of Florida.
  2. What such advice neglects to consider is that the roots will grow back!
  3. Some other articles will suggest adding 5-10 cm of planting medium on top of the existing soil before planting. However, the roots will simply grow up in that shallow space (As you’ve noticed, the roots have taken over the soil you amended.) And that’s not deep enough for those plants, anyway.

All that said, then, you are correct in thinking this is not the right spot for Irene’s plants.

Find another spot for them, or actually, several spots, since they have differing light needs. Roses, for example, are full sun lovers, while the Astilbe and Crevice Alumroot (Heuchera micrantha) will be happy in part shade or even more shade. Make a list of all the plants, check their light (and moisture) needs and plant groups in most suitable spots.

That way, you will think of Irene several times as you walk around your garden.