Will Lily Of The Valley Grow Under Black Walnut Trees

Lily of the valley will not grow well under black walnut trees because black walnuts produce a toxic chemical called juglone.
 
Juglone is a natural herbicide that leaks from the roots, bark, leaves, and nut hulls of black walnut trees.
 
If you’ve been asking, “Will lily of the valley grow under black walnut trees?” the short answer is no, and it’s because of that juglone.
 
Most plants sensitive to juglone, including lily of the valley, struggle or die when planted within the root zone of a black walnut.
 
In this post, we’ll explore why lily of the valley won’t grow under black walnut trees, what juglone does to the plant, and what you can do instead if you really want that sweet-smelling ground cover near a walnut tree.
 
Let’s get into it.
 

Why Lily of the Valley Won’t Grow Under Black Walnut Trees

Lily of the valley won’t grow under black walnut trees, and here’s why:
 

1. Juglone Is Toxic to Lily of the Valley

The main reason lily of the valley won’t grow under black walnut trees is juglone.
 
This chemical is produced by the tree and released into the soil.
 
When lily of the valley roots absorb juglone, it disrupts their ability to take in water and nutrients.
 
The result is a plant that wilts, yellows, and eventually dies even if you water it regularly.
 
Juglone is so potent that even a small amount in the soil can harm a lily of the valley within weeks.
 

2. Lily of the Valley Is Highly Sensitive to Juglone

Not all plants react the same way to juglone.
 
Some tolerant plants like ferns, hostas, and daylilies can survive near black walnuts.
 
But lily of the valley is on the sensitive list.
 
It’s one of those plants that just can’t handle the chemical.
 
So if you plant lily of the valley under a black walnut tree, you’re basically setting it up for failure.
 

3. The Root Zone Extends Far Beyond the Canopy

Even if you plant lily of the valley a few feet away from the trunk, it might still be in the danger zone.
 
Black walnut roots spread wide, often extending 50 to 80 feet from the tree.
 
That means the juglone in the soil can reach lily of the valley planted well beyond the drip line.
 
So “under the tree” doesn’t just mean directly beneath the branches.
 
It means anywhere within that sprawling root zone, which is why lily of the valley will not grow under black walnut trees in most cases.
 

Signs Lily of the Valley Is Struggling Under a Black Walnut

If you already planted lily of the valley under a black walnut, you might notice these signs:
 

1. Yellowing Leaves

One of the first signs that lily of the valley is struggling under black walnut trees is yellowing foliage.
 
The leaves start to lose their vibrant green and turn pale or yellow.
 
This happens because juglone interferes with chlorophyll production.
 
Without healthy chlorophyll, the plant can’t photosynthesize properly, and it slowly declines.
 

2. Stunted Growth

Lily of the valley that’s exposed to juglone often stays small and weak.
 
It might send up a few leaves, but they won’t spread into a lush carpet like healthy lily of the valley does.
 
The plant’s energy is going into survival rather than growth.
 
So instead of a thick patch, you get a few sad-looking sprouts.
 

3. Wilting Despite Moist Soil

You might water your lily of the valley faithfully, but it still wilts.
 
That’s because juglone damages the roots, making it hard for them to absorb water.
 
So the plant looks thirsty even when the soil is damp.
 
Eventually, the roots rot, and the lily of the valley dies.
 

What to Do Instead If You Want Lily of the Valley Near a Black Walnut

If you really want lily of the valley but you have a black walnut tree, you still have options:
 

1. Plant in Containers

One workaround is to grow lily of the valley in pots.
 
Use fresh potting soil that hasn’t been exposed to juglone.
 
Place the containers on a patio or deck away from the black walnut’s root zone.
 
This way, you can enjoy lily of the valley without the tree’s toxic reach.
 
Just make sure the pots aren’t sitting directly on soil contaminated by walnut roots.
 

2. Choose Juglone-Tolerant Ground Covers

If you want a ground cover under your black walnut, skip lily of the valley and choose something tolerant.
 
Good options include wild ginger, creeping phlox, and vinca minor.
 
These plants can handle juglone and will actually thrive where lily of the valley would fail.
 

3. Create a Raised Bed with a Barrier

Another option is to build a raised bed with a solid bottom barrier.
 
Line the bottom with landscape fabric or a wooden base to block walnut roots from entering.
 
Fill it with clean topsoil and plant your lily of the valley there.
 
As long as the roots stay separated from the black walnut’s root zone, your lily of the valley has a chance.
 

So, Will Lily of the Valley Grow Under Black Walnut Trees?

Lily of the valley will not grow under black walnut trees because of juglone toxicity.
 
The chemical stunts growth, yellows leaves, and eventually kills the plant.
 
If you want lily of the valley near a black walnut, you’ll need to use containers or raised beds with barriers.
 
Otherwise, choose a juglone-tolerant ground cover instead.
 
Hope this post has helped you understand why lily of the valley won’t grow under black walnut trees and what to do about it.