Black Walnut Toxicity Dilemma

Houston... we have a problem.

After going to a new garden center today, where I discovered a very knowledgeable owner, I stumbled upon some information that was quite daunting.

Black walnut trees produce a phytotoxin that inhibits growth of most plants.


That tree that I planted hostas at the base of?  Yep.  Black walnut.  Not only that, but there are three black walnut trees in our yard.  Two in front and one in the back.  Ugh.  Fortunately, hostas are resistant to the toxin that the black walnut produces.

I've been reading up on black walnut toxicity since I discovered this nasty bit of information, and everything I've read matches what was said by the garden center's owner.  Of course, I knew that was going to be the case.  He's one of those people that you can instantly recognize as a good information source.

The toxin that he was referring to is called juglone, or 5 hydroxy-1, 4 napthoquinone if you speak Chemistry.  According to the Ontario Ministry of Agriculture, Food, and Rural Affairs, juglone inhibits respiration in sensitive plants, causing dwarfed growth in some cases, and death in others.  This can happen slowly, or it can happen in as little as two or three days!  Scary stuff.

There's hope for me, though.  If you check out the ministry's link in the preceding paragraph, they have a list of tolerant plants.  Not only are hostas in that group, but so are a few other food crops, such as beets and onions.  Plants with shallow roots seem to do better than deep-rooted counterparts.

I can also lay down a barrier of some sort (such as landscaping fabric) to help keep this toxicity at bay, and create a raised bed.  Unfortunately, I was told at the garden center that I should raise the bed as high as 18 inches, and that's a lot of dirt.  It may be workable, though, so I'll see if I can come up with any interesting ideas. 

If worse comes to worse, there's always container planting...

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