Black Walnuts Popping Up All Over The Place

(Question)

Dear Master Gardeners,
I’m a volunteer gardener at my Toronto apartment building. The problem that I’m going to tell you about is situated in a large concrete planter which hugs the side of my building; the planter is quite large; it is filled with rich soil & has got plenty of shrubs too. This one particular plant keeps popping up through the soil in different spots. There are several of them now & I believe they are baby versions of a large tree that was removed from that planter. The new ones are not welcome. It is as if they have an underground network & when u pull out 1 another 1 just comes up somewhere else. Can you tell me what it is? How do i get rid of them? I’ve got a bunch of spring bulbs in that spot & I don’t want this strange tree getting in the way. Thanks for any light you can shed.

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(Answer)

Thank you for contacting Toronto Master Gardeners.

You may have a common weed tree, the black walnut. To get rid of them, you have to remove all of them. Don’t cut them down; they will come back even stronger.

  1. When you find a seedling of this tree just pull or dig it out.
  2. If the seedling becomes a tree, you have to kill it by girdling. To girdle a weed tree, cut a one inch or more strip of bark off from around the trunk. Make sure to cut deep enough to penetrate the hard centre of the trunk. Doing this will slowly kill the tree over a period of a year or two and reduces the chances of the tree producing suckers.

Another possibility is smooth sumac or Rhus glabra.  According to the Missouri Botanical Gardens, smooth sumac is a deciduous shrub which occurs on prairies, fields, abandoned farmland, clearings and along roads and railroads. It is a large, open, irregular, spreading shrub which typically grows 8-15′ tall and spreads by root suckers to form thickets or large colonies in the wild.  It is weedy and tends to spread aggressively,  so using the above method for removal is recommended.

Good luck !