What Not to Plant Near a Black Walnut Tree?

To ensure the health of surrounding vegetation, knowing what not to plant near a black walnut tree is essential. Homeowners often choose black walnut trees to add a touch of sophistication to their landscape. However, planting certain plants near a black walnut tree can harm their growth and health.

Due to the toxic effects of Juglone, a chemical produced by black walnut trees, it is essential to consider which plants should not be grown near this tree. This article will cover some examples.

Black Walnut Tree

Which kind of walnut tree produce toxic chemical?

Before we examine what plants do not grow next to this tree, we must first know which walnut trees produce Juglone.

All kinds of walnut trees that trees generate Juglone, including:

  • English walnuts
  • Butternut (white) walnuts
  • Pecans
  • Black walnuts

Generating Juglone by these trees, a toxic chemical detrimental to the growth of other plants.

Among walnut varieties, Black walnut produces the highest amount of Juglone.

Which kind of walnut tree produce toxic

Why can other plants not grow a nearby walnut tree?

All kinds of walnut trees produce hydroquinone, which is a non-toxic chemical. This chemical is all over the walnut tree, including leaves, bark, and roots. When leaves fall over the soil, it makes it toxic, and the seeds are in the ground. When hydroquinone is released into the air or dirt, it becomes toxic since it turns into Juglone.

Juglone in the soil inhibits the growth of nearby plants and even kills them by starving them of oxygen and water. Juglone does not readily dissolve, and it remains in high concentration. Even if you cut the tree, Juglone does not remove easily from the soil; you should be patient for many years before planting another plant there. Until the whole root decays, the ground will contain Juglone.

As a toxic chemical, Juglone gives black walnut trees an allopatric effect, hurting other plants’ growth. Other factors that can affect the development of other plants in a nearby walnut tree are leaf canopy, light restriction, and water restriction.

black walnut trees

What does Allopathy mean?

Allelopathy, as an evolutionary property, means that some plants release chemical material to hinder the growth of nearby plants. Since they don’t allow other trees to grow around them by producing toxic chemicals and absorbing all sunlight and soil nutrients, they reduce competition with other plants.

While some plants, through evolution, have become resistant to this toxic chemical, some plants are sensitive to Juglone and cannot compete with the black walnut tree. You may wonder which plants cannot grow near this tree.

What plants should not be planted close to a black walnut tree?

Let’s see which type of plants cannot grow near this tree in two categories depending on whether it is vegetable or tree.

Vegetables that should not be planted next to black walnuts:

  1. Asparagus officinalis
  2. Brassica spp (Cabbage)
  3. Cucumis sativus (Cucumbers)
  4. Solanum melongena (Eggplant)
  5. Capsicum spp (Peppers)
  6. Solanum spp (Potato)
  7. Thymus vulgaris
  8. Solanum spp (Tomatoes)
  9. Melons
  10. Beans
  11. Sweet corns
  12. Onions
  13. Carrots
  14. squash

Vegetables that not be planted next to black walnuts

Trees that do not to plant near a black walnut tree

  1. Malus spp (Apple Trees)
  2. Tilia spp (Basswood)
  3. Alnus glutinosa (Black Alder)
  4. Populus (Cottonwood )
  5. Malus (Crabapple Trees)
  6. Cupressus (Cypress)
  7. Pinus strobus (Eastern White Pine)
  8. Celtis occidentalis (Hackberry)
  9. Magnolia grandiflora (Magnolia)
  10. Pinus mugo (Mugo Pine)
  11. Picea abies (Norway Spruce)
  12. Pinus resinosa (Red Pine)
  13. Pinus sylvestris (Scots Pine)
  14. Acer saccharinum (Silver Maple)
  15. Betula papyrifera (White Birches)
  16. Elaegnus angustifolia (Russian Olive)
  17. Persimmon
  18. Peach
  19. Cherry
  20. Plum

Flowers that cannot grow near the black walnut tree:

  1. Blue False Indigo
  2. Buttercup
  3. Chrysanthemum
  4. Columbine
  5. Flowering Tobacco
  6. Forget-me-not
  7. Hydrangea
  8. Lilies
  9. Lily of the Valley
  10. Peonies
  11. Petunia
  12. Rhubarb
  13. Crimson Clover

plants that don't grow next to black walnut trees

Shrubs or Vines that should not be planted next to black walnuts:

  1. Blueberry
  2. BlackBerry
  3. Mountain Laurel
  4. Grapes
  5. Amur Honeysuckle

How long it takes to get rid of Juglone in the soil after removing the Black walnut tree?

Do you want to plant new trees in your garden and add aesthetic appeal to your landscape after removing black walnut trees from your area?

It is possible since there is some variety of bacteria that heavily rely on Juglone for their life. The Pseudomonas Putida J1 would feed Juglone in the soil quickly if the soil is aerated. But they need time to break down the entire Juglone in the ground.

A final word about plants that don’t grow next to black walnut trees

The black walnut tree is one of the varieties of the walnut family that produce more toxic chemicals than other types of walnut trees.

The high amount of Juglone released by this variety inhibits the growth of other plants. However, some plants become tolerant to this toxic chemical through evolution and can thrive well.

This article lists plants that cannot grow nearby black walnut trees. We hope reading this article helps you to find the right plant for your garden and make the most of your garden space. If you have any experience planting a particular type of plant nearby your black walnut tree, please share it with us in the comment section.

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