So you want to know “will daffodils grow under walnut trees?”.
Well, it is a legitimate question in light of some of the unique properties of the walnut tree.
Not all plants will grow around a walnut tree, but is the daffodil one of them?
Let’s find out.
Will Daffodils Grow Under Walnut Trees?
Daffodils are tolerant of juglone, the chemical produced by walnut trees that is deadly to many species of plant, so yes you can grow daffodils under walnut trees. However, if they are planted in an area with an extremely high level of juglone they could still be affected. Your best bet is to plant your daffodil at the edge of the leaf canopy so it is further from the trunk where juglone levels are highest, and so it gets the bright sunlight it needs to thrive.
The Problem With the Walnut Tree
There are two main types of walnut tree, the black walnut tree and the English (or Persian) walnut tree.
The black walnut tree is native to North America and the English walnut tree grows right across Southern Europe down to Southern China.
The two main species have some differences.
The black walnut tree is found widely in the wild, whilst the English walnut tree is more of an ornamental tree found in parks and gardens.
The nut from the black walnut tree also has a much richer and more distinctive flavor than its English compatriot.
But they both share one common trait, something that makes them toxic to many plants…
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What Is Juglone?
All species of the walnut tree produce a chemical called hydrojuglone as a way of defending their territory.
In itself hydrojuglone is non-toxic, but when it is exposed to air or soil it gets oxidized and turns into something called juglone
This is when the problems start.
Juglone is harmful to many plants as it starves them of oxygen and water.
What is more, juglone doesn’t dissolve very well, so it builds up at the base of the walnut tree, where it is highly concentrated.
Therefore there are simply many plants that you cannot grow beneath the canopy of a walnut tree.
Juglone can severely damage and kill certain plants even if they are growing up to 80 feet from the trunk as that is often how far the roots extend.
As mentioned right at the start of this section all species of the walnut tree produce juglone, but black walnut trees produce it in the highest concentration.
Are Daffodils Juglone Tolerant?
Ok so if you want to know if daffodils will grow under walnut trees, then we have some good news for you.
Yes, they will.
Daffodils are juglone tolerant and are a good way to add some color beneath a walnut tree.
However, just because they are tolerant to juglone it doesn’t mean the conditions are ideal for them.
They may still experience some problems, which we cover further on in this article.
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What Else Can You Plant Next to a Walnut Tree?
So we have established you can grow daffodils under walnut trees, but what else can you plant there?
Well, bulbs in general are a pretty safe bet. Several flowering bulbs will tolerate high levels of juglone.
These include crocus, snowdrop, Siberian squill, winter aconite, glory-of-the-snow, muscari, tulips, Spanish bluebell, grape hyacinth and most Dutch hyacinth,
Other plants tolerant to the conditions of a walnut tree include:
- Beans, beets, carrots, corns, melons, onions, parsnips and squash
- Black raspberries, cherry plums, nectarines, peaches, pears and quince
- Begonias, hydrangeas, impatiens, marigolds, morning glories, violets and zinnias.
If you are unsure, then your best bet is to ask your local garden center for advice or check the list of juglone tolerant and non-tolerant plants on the Ontario Ministry Of Agriculture, Food And Rural Affairs website.
What Are the Symptoms of Juglone Toxicity?
Bear in mind that even if a plant is considered juglone tolerant, it might still develop problems if levels of juglone in the soil are particularly high, or if the plant is under stress from other factors as well.
Symptoms of juglone toxicity vary from plant to plant, but generally affected plants start out by displaying what is known as ‘walnut wilt’.
This sees plants visibly wilt, even if the soil around them is moist. Sometimes it may only be part of the plant, sometimes it might be the entire plant.
This wilting can develop into leaves turning yellow or brown, the stems discoloring and growth being stunted.
Often it can happen very quickly, in a day or two in some cases.
Plants damaged by walnut toxicity cannot be saved, and unfortunately must be dug up and thrown out.
So even though daffodils are considered juglone tolerant, they could still be affected by it.
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How Should You Plant Daffodils Around a Walnut Tree?
Ask yourself this.
Will daffodils grow in a shaded area?
Daffodils can tolerate light shade but they do like at least six hours of bright sun each day.
So another issue you could face if you plant daffodils under a walnut tree is the shade.
If you are planting daffodils beneath a walnut tree, then the best position for them is closer to the edges of the leaf canopy.
Here the light is brighter, and it is further from the trunk of the tree where juglone levels will be at their highest.
You could also consider improving the soil around the tree by adding a layer of compost that is a couple of inches thick.
Or you could even create a raised bed, covered with a thick layer of mulch, to limit contact with the roots of the walnut tree.
The chemical juglone means that growing many plants under a walnut tree, and a black walnut tree in particular, is a no-no.
Daffodils however are tolerant of juglone, and with proper care and attention can grow well under a walnut tree.
That doesn’t mean they are completely immune to the effects of juglone, and you will need to keep a close eye on them if they are growing in an area with particularly high levels of juglone.
But if you don’t plant them right next to the trunk, and ensure they get the light they need each day, then you should be able to grow daffodils under a walnut tree without major issue.
Remember though that plenty of plants won’t tolerate being even within 80 feet of a walnut tree.
So do your research before you plant anything around a black walnut tree.