I have 3 nice cedars in a back garden that was overrun by goutweed. About a year ago, I cover all the goutweed with tarps to hopefully kill it off. I need to move the cedars and wondered if i can safely move them to a new spot right away. I had read that it is best to put them in a temporary container for 3-4 months to make sure the goutweed doesn’t grow back before putting in a new spot. I am closing a large pool and the new area won’t be available for some time anyway…so a few questions here. Many thanks!
Hello thank you for contacting the Toronto Master Gardeners for advice on moving your cedars. It sounds as if you have already done some research and have discovered just how invasive goutweed can be. I’m glad to hear you are going to “rescue” your nice cedars. Typically the best time to move any plants especially trees is either in the late fall or early spring when trees are dormant. But if you would like to tackle the goutweed problem sooner than later I would wait for a time when its not so oppressively hot. Choose a day that is rainy, overcast and cool, and even better if the weather is forecasted to stay that way for a few days. I like your idea of temporarily housing your trees in containers to watch out for goutweed before replanting. Make sure your containers have good drainage and are filled with container soil mixed in with some organic compost. Try to remove as much of the goutweed root as you can. Remember that leaving only as small bit of root will allow a new plant to grow! I have found that gingerly hosing the roots makes separating out the goutweed easier. Keep the trees well watered and in a partially shaded position until you are ready to place them in their permanent spot. It will be nearly impossible to completely eradicate the goutweed, so you will have to keep an eagle eye out for any “invaders”.. An important step would be to mulch heavily, leaving a clear space around the base of each tree.
I have included some links to similar subjects tackled by colleagues at the Toronto Master Gardener website. These relate to goutweed and to growing cedars in containers. I hope you find them useful
Also included is our Gardening Guide for using Mulch. This will be a helpful tool in controlling weeds and invasive plants.