Will Lily Of The Valley Grow Under Black Walnut Trees

Lily of the valley will not grow well under black walnut trees because black walnut roots produce a substance called juglone that is toxic to many plants.
 
Juglone is a natural herbicide that gives black walnut trees a competitive edge, but it spells trouble for sensitive garden plants like lily of the valley.
 
So if you’ve been asking yourself, “will lily of the valley grow under black walnut trees,” the short answer is no—not without a serious fight.
 
In this post, we’ll look at why lily of the valley struggles under black walnut trees, what juglone actually does to plants, and whether there’s any way to make this pairing work.
 

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

Lily of the valley is a beautiful, shade-loving perennial, but it has one big weakness when it comes to black walnut trees.
 
Here’s why this pairing usually fails.
 

1. Juglone Is Toxic to Lily of the Valley

Black walnut trees produce juglone in their roots, leaves, bark, and nut hulls.
 
Juglone is a chemical that interferes with a plant’s ability to take up water and nutrients.
 
Lily of the valley happens to be one of the many plants that is highly sensitive to juglone, which means it will wilt, yellow, and eventually die if planted too close to a black walnut.
 
Even if it survives the first season, the plant will slowly decline over time as the juglone builds up in the soil.
 

2. The Root Zone Extends Far Beyond the Canopy

One of the biggest mistakes gardeners make is assuming that the black walnut’s toxic zone only goes as far as the branches overhead.
 
In reality, black walnut roots can extend well past the dripline of the tree, sometimes two to three times the width of the canopy.
 
That means even if you plant lily of the valley a few feet away from the trunk, the roots could still reach it.
 
So when you wonder if lily of the valley will grow under black walnut trees, you also have to consider the roots nearby.
 

3. Juglone Persists in the Soil for Years

Even after a black walnut tree is removed, juglone can remain in the soil for several years.
 
This is bad news for lily of the valley because it can’t just wait out a season or two and then bounce back.
 
The toxin lingers, and sensitive plants will keep struggling until the juglone finally breaks down.
 
So if you’re planning to grow lily of the valley under black walnut trees, know that the soil itself is working against you.
 

What Juglone Does to Lily of the Valley Plants

When lily of the valley is exposed to juglone, the damage shows up in a few predictable ways.
 
Understanding these symptoms can help you confirm whether black walnut toxicity is the problem.
 

1. Wilting and Yellowing Leaves

The first sign is usually wilting, even when the soil is moist.
 
Leaves then turn yellow and brown at the edges, and the plant looks like it’s dying from drought—but water won’t fix it.
 
This happens because juglone disrupts the plant’s internal water transport system.
 

2. Stunted Growth and No Flowers

Lily of the valley that survives juglone exposure often stays small and never produces its signature fragrant white bells.
 
The plant is simply too stressed to put energy into blooming.
 
Over time, the leaves get smaller, and the whole clump shrinks rather than spreading like it normally would.
 

3. Gradual Decline and Death

Eventually, the plant dies back completely.
 
This can take a season or two, but once juglone has a hold on lily of the valley, recovery is rare.
 
That’s why most gardening experts recommend skipping lily of the valley under black walnut trees altogether and choosing juglone-tolerant plants instead.
 

Can You Make Lily of the Valley Grow Under Black Walnut Trees?

If you’re determined to try, there are a few things you can do to give lily of the valley a fighting chance near a black walnut tree.
 
Just know that even with these strategies, success is not guaranteed.
 

1. Plant in Raised Beds or Containers

The most effective way to grow lily of the valley near black walnut trees is to keep its roots out of the toxic soil entirely.
 
Use raised beds lined with landscape fabric or grow the plants in containers on a patio or deck.
 
This creates a physical barrier between your lily of the valley and the juglone in the ground.
 

2. Clean Up Walnut Debris Quickly

Leaves, twigs, and nut hulls from black walnut trees are loaded with juglone.
 
Rake them up and dispose of them rather than leaving them to break down in your garden beds.
 
This won’t eliminate the juglone already in the soil, but it slows the buildup and gives your lily of the valley a little more breathing room.
 

3. Improve Soil Drainage and Add Organic Matter

Juglone breaks down faster in well-drained, biologically active soil.
 
Mixing in compost and keeping the area from getting waterlogged can reduce how long the toxin sticks around.
 
Still, this is more of a long-term fix, and lily of the valley under black walnut trees will always be a risky bet.
 

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

Lily of the valley will not grow well under black walnut trees because juglone toxicity makes the soil hostile to this delicate perennial.
 
You might get a season or two of growth, but the plant will eventually decline and die as the juglone takes its toll.
 
If you really want lily of the valley in your garden, plant it far away from black walnut trees, or grow it in containers where its roots never touch the toxic soil.
 
The easiest path is to accept that lily of the valley and black walnut trees just don’t mix, and choose juglone-tolerant shade plants instead.
 
That way you save yourself the frustration of watching your lily of the valley slowly fade away.