Hi! I'm trying to figure out what I can get away with under this red oak in New England. It's gonna be dry and it's gonna be shady and it's gonna be allelopathic. I dumped a bunch of compost in it over the summer.



I'd like to try kerria japonica, Solidago caesia, red columbine, heuchera, hakone, and some epimedium.

And a little further out, like toward the bottom right corner of this pic, I'm thinking about an oakleaf hydrangea.

Anyone have any advice for me?

Alex, just curious why you think it may be allelopathic? Never heard of that issue with oaks, possibly the deep shade and I noticed some maple leaves, maples have lots of roots which suck a lot of water, plus they tend to be near the surface.

Welcome to the site!

Good eye! There is indeed a maple tree right behind the oak tree.

I've heard allelopathy from a couple of friends and a couple of places online, which I can't link to because of new-member restrictions on posting outside links. (But for anyone who's interested, if you google red oak allelopathy you'll find a few things.)

Perhaps red oaks are more allelopathic than other oaks? Not, like, black walnut allelopathic but maybe an effect.

When planting shade garden plants... I'd worry less about those plants having issues with the trees...
they evolved to fill that niche!

I do think that you are trying to plant more there than the site can support...

If you want to go perennials, fine...
if you want to go shrubs, fine...

but... it just looks too small there for both.

Planting under trees can be difficult... finding any soil among the roots.
even just planting perennials... you are going to have to back away from the trunk...

although... there are shallow rooted perennials that would happily fill that area in right up to the trunk... like strawberry begonias.... and some of the native running ferns...

Thanks for your response, stone. Are you suggesting that there just won't be enough nutrients in there to support all that stuff, after the tree's done sucking its stuff out? I hadn't even thought of that.

Actually, no.
it's about room for the plants to breathe.
when too many plants are all jammed together... there's often problems... with lack of air-flow, which may create likely conditions for fungus diseases and... I don't know, the plants just aren't happy and none of them will look their best.

I'd avoid suggesting that the tree is "sucking" out the nutrients... as I stated earlier, the plants evolved to fill that niche. as long as you are top-dressing with compost and mulch each year (and leaving the oak leaves where God intended)... there shouldn't be nutrient issues.

OK, thanks! You've given me a lot to think about, and I do think step #1 is I'm going to go much lighter over there, just kinda ease into it a little. Very much appreciate the expertise.

Before you acquire any plants, do look at their width as well as their height when fully grown. Since I'm using my phone it's harder for me to get a good look at the space in your picture.

I have 2 very large red oaks and am always amazed at their roots. They seem to extend forever and are fairly shallow. I say this with confidence having stubbed my toes too many times.

I also have oakleaf hydrangeas. They can grow pretty big depending on the variety. Don't know your other plants except for columbines and heuchera. I live in a very different climate and in the heat of the South those plants like a lot of water.

So anyway, you're correct in thinking that you should go slow. That's just my opinion. stone knows much more than I do.

The oaks are not a chemical problem just a deep shade problem. Here we find mondo grass loves them. The root area is actually a moisture source. Buxus and other shrubs like Daphne will grow under ours (8a).