Laidback Gardener Tip of the Day Trees

Gardeners: Beware of Shallow-Rooted Trees!

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Source: www.bowerandbranch.com

If you’re searching for trees to plant on your property, one factor to consider is the type of roots it produces, and this is especially true if you’re an avid gardener.

You see, some trees have roots that grow especially deep or are well spaced. These trees won’t hamper your gardening plans, even in the long term (unless the soil where you plan to garden is very thin; after all, even a normally deep-rooted tree will produce surface roots if there is, for example, a layer of solid rock just below the soil surface).

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Tain’t easy maintaining a lawn with shallow-rooted trees in the vicinity. Source: omlinsonbomberger.com

Other trees, on the contrary, have either dense root systems or mostly superficial roots that will quickly create havoc, drying out the soil and depleting its minerals, making any type of gardening difficult. And many of these same trees will cause further damage by lifting the tiles of your patio, cracking and raising ciment walkways and rendering the surface of your paths and trails so uneven you can scarcely walk on them without tripping. It’s even difficult to maintain a decent lawn under such trees, as the roots not only dry out lawn grasses and steal their minerals, but often rise above the soil making mowing difficult! Certainly the trees below can be useful in a city park, a wood-lot or on a large lot, but they are not good choices if you think you’ll be gardening one day.

Note that the situation is even worse near a vegetable garden. Vegetables are delicate things, requiring deep, friable, rich soil. You don’t want tree roots of any sort wandering in. Ideally, therefore, you could avoid any tree, even one said to have deep roots, near a vegetable garden. Don’t even plant shrubs nearby! Or, looking from another point of view, one of the basic criteria in the selection of the site for any future vegetable bed should always be the absence of any tree or large shrub in the area.

The Culprits

Here are some trees with superficial or very dense roots that you should avoid planting if you want a beautiful lawn, a stunning flower bed or a productive vegetable garden.

  1. Acacia (Acacia spp.)—zones 9–11
  2. Alder (Alnus spp.)—zones 2–10
  3. Amur maple (Acer tataricum ginnala)—zones 2–7
  4. Arborvitae (Thuja spp.)—zones 3–9
  5. Ash (Fraxinus spp.)—zones 2–9
  6. Beech (Fagus spp.)—zones 3–7
  7. Black locust (Robinia pseudoacacia)—zones 4–9
  8. Cork tree or hellodendron (Phellodendron spp.) – zones 4-8
  9. Cypress (Cupressus spp.)—zones 6–10
  10. Desert willow (Chilopsis linearis)—zones 7–9
  11. Elm (Ulmus spp.)—zones 3–9
  12. Eucalpytus (Eucalyptus spp. )—zones 7–10
  13. European white birch (Betula pendula)—zones 2–7
  14. Fir (Abies spp.)—zones 2–8
  15. Hemlock (Tsuga spp.)—zones 4–8
  16. Japanese cherry (Prunus serrulata)—zones 6–9
  17. Katsura tree (Cercidiphyllum japonicum) – zones 5-8
  18. Larch (Larix spp.)—zones 1–8
  19. Liquidambar (Liquidambar spp.)—zones 6–9
  20. Magnolia (Magnolia spp.)—zones 4–11
  21. Mezquite (Prosopis spp.) – zones 7–11
  22. Mulberry (Morus spp.)—zones 4–9
  23. Norway maple (Acer platanoides)—zones 3–7
  24. Pepper tree (Schinus spp.)—zones 8–11
  25. Pin oak (Quercus palustris)—zones 4–8
  26. Poplar (Populus spp.)—zones 2–9
  27. Red maple (Acer rubrum)—zones 3–9
  28. River birch (Betula nigra)—zones 3–9
  29. Silver maple (Acer saccharinum)—zones 3–9
  30. Spruce (Picea spp.)—zones 2–8
  31. Sugar maple (Acer saccharum)—zones 4–9
  32. Sycamore or plane (Platanus spp.)—zones 5–9
  33. Tulip tree (Liriodendron spp.)—zones 5–9
  34. White pine (Pinus strobus)—zones 3–9
  35. Willow* (Salix spp.)—zones 1–10
  36. Yellow birch (Betula alleghaniensis)—zones 2–7

*Shrub willows have more limited root systems than tree willows and can be used near a flower bed… but never near vegetables!

The Good Guys

You’ll find a list of trees with deeper roots here: Garden-Friendly Trees. Still, don’t plant any of even these near a vegetable garden!20180327A www.bowerandbranch.com

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

6 comments on “Gardeners: Beware of Shallow-Rooted Trees!

  1. Why is magnolia on both the good and bad list?

    • Oops! I’ve corrected the “good list” to specify “shrubby magnolias”. All are shallow-rooted, but shrubby species produce relatively few roots and are not likely to do damage.

  2. Blackbeered

    I was shocked to see that my Japanese Cherry and River Birch [both on the chopping block for this Fall] didn’t make the list … they should be in the “Top 5”. While they look great and provide needed shade, grass has no chance in my backyard.

    Zone 7b.

    • Thank you for the suggestions. I always update my site when necessary and will do so here!

      • Blackbeered

        Thx.

        First, the River Birch has no business in my clay-for-soil backyard. I’ve lived here since the house was built [1996] and I can’t remember how it got there. It’s magnificent, each of the four shoots are over 45′ tall and the canopy has to be 30′. That said, I’ve got hundreds of feet of 2″ roots at the surface, climbing the 5% uphill towards the source of shedding water [off the driveway] 40 feet away. Now, if it was where it belonged, maybe the roots would have dove deep.

        Second, the Chinese cherry is gorgeous too; 20′ tall with 20′ canopy; and a trunk that’s 12″ in diameter! It, too, is sending surface roots up over toward the same driveway [siphoning off some of the birch’s water]; it’s 10′ off the driveway.

        If you believe the roots-to-canopy ratio, you can see I’ve got roughly a 30’x100′ area where grass has no chance. And with no grass, any topsoil I once had at the base of those trees has scoured down to the other “wild” side of my property.

        So that’s why I visited your website. Once those tree are down, and I’ve recovered from the wounds my neighbor’s going to inflict for me doing so, I’ll want to plant a tree less problematic.

      • By the way, the river birch was already on the list. I only added the Japanese cherry.

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