OP,
What are your fruit trees? If you grow stone fruit, cherries, peaches, plums, can those fruit trees be grown with no spray or minimal spray?
Like @alan mentioned above, the OP could inadvertently kill good bugs as weel as bad bugs if he needs to spray to protect his fruit.
If he decides to spray and want to plant some something under his trees, he should consider non-flowering plants.
Thanks! This has been an interesting adventure for sure … I tried to make obvious stupid errors while at the same time moving forward and constantly learning. I think right now I’m mostly learning what the areas are that I know nothing about. I figure later on I’ll get more focused on solving specific problems.
In this area I have 3 plums, 2 pears and 3 cherries. If I take one thing away from this thread, it’s reinforcing the absolute necessity of protecting bees and other beneficial insects, and understanding how the timing of flowing plants under the trees affects that. I don’t know if I’m going to need to spray or not … that’s a big hole in my knowledge and lack of understanding what problems I might or might not encounter.
I was thinking about exactly this problem earlier today.
My original thinking was to focus on something pretty, but I’m liking the rhubarb idea.
rhubarb is bullet proof here. i barely fertilize and it gets huge stalks. im thinking of putting in a row of 10 and selling it at the farmers market . i have a old heirloom green stalked one and 4 Canada red the Canada red is sweeter/ more tender and more productive. so far spraying hasnt been a issue as its mostly spring and late summer so the lower plants arent blooming oir are done fruiting when i need to spray. also you will notice if you grow onions, garlic, marigolds and some herbs, they will keep you from needing to spray as much for bugs . also try to pick resistant varieties of plants to lessen the need for sprays in the 1st. place. it can be done. the net and fruit growing sites like this is your best source for that knowledge. 
I had some old rhubarb seeds lying about, so I just put them in small nursery pots to see if I can get them to germinate. Meanwhile … investigating this Canada red of which you speak 
if got some goosberries and lots of herbs planted between/beneath the tree’s.
Im not spraying now though. and in a completely different climate.
Im happy with this topic though because it makes me think about flowering times of my underplanting.
I don’t know about rhubarb, it is basically a giant dandelion with edible stalks. If the soil next to your trees is any good it would put a huge tap root and compete hard with the tree.
I have been thinking of doing lowbush cranberries and lingonberries. I have strawberries elsewhere so I may chuck a few under to see how they behave.
Around the Belgian fence in our front yard, I have planted:
Daffodils along the row of the fence, about one foot from the trees. Nice in the spring. The daffodils are mostly Thalia, fragrant and nice for cuttings. We also have tulips but they’re not in the area immediately around the trees.
Herbs along a path that runs between the fence and our porch: currently lavender, English thyme, sage, catmint, chives and Chinese chives. The nearest are set back about two feet from the trees. This is still a work in progress, but while the trees probably shade the herbs a bit more than is optimal for some of them, the herbs don’t seem to be doing any harm to the trees that I can tell.
A belt of oxeye daisies and Northern blue flag irises along the street. This looks nice, seems to help with weed control, and creates a bit of a barrier between the trees and the street. The irises are a bit tricky, in that they will need to be divided every so often, so I’ve tried to keep them a bit further away from the trees. But at this point, they don’t seem to be interfering with the trees too much.
The whole area is about sixteen feet wide by sixty feet long and is mulched with wood chips. I don’t currently spray anything at all, and in our particular situation I can’t see myself spraying anything more toxic than Surround, so I feel like I’m doing the bees more good than harm with the underplanting.
All still a work in progress, and I’m planning to fill in/mix in things as I go, but it’s coming along.
Rhubarb does not have a taproot. Not sure that matters to your argument, but just to keep the record straight, while it has a very vigorous and deep root system, it has no central, penetrating root. Roots are in fact, rhubarb’s one vulnerability. If it can’t reach deep because of hard pan or has wet feet because of perched conditions, it will fail due to various root rots.
I think you could legitimately ask whether rhubarb is a nutrient hog that is incompatible with dwarf plantings. But a certain amount of nutrient, and more particularly, water, tie-up is the point, as discussed earlier in the thread. Other than N, there should be no nutrient removal, unless you harvest and haul away a lot of rhubarb.
My experience is not directly relatable to the Pacific Northwest, were Rhubarb will have somewhat different annual habit than in super cold winter, hot summer of the upper Midwest, but I can tell you that I have thriving rhubarb fed nothing but mulch for 35 years, and it is not holding back the plants next to it at all. Just up the road from us, well into the 1990s, there was a rhubarb patch that had been planted in the early 1900s as part of the farm garden of an old folks’ home that grew much of their own produce before WW II. About 25’ feet square, and with no particular attention other than removing the occasional perennial weed invasion (not much - those big rhubarb leaves are a pretty darned good weed suppressor all by themselves), it was still going strong after 8 decades, getting enough N from thunderstorms and normal soil metabolism, and recycling everything else, since nothing was removed from the patch, practically speaking, after the 1940s.
even in old neglected grown over farmland , you still see the rhubarb planted many decades ago growing in high grass. as long as its not shaded out completely by bushes and trees, it will survive. i would never plant rhubarb under trees but in between, 8-10ft away is fine.
They do if the soil is right, and the soil around my trees is just the right sort of right. This is what they do when given a chance:
And they put those roots to really good use, they are voracious eaters. Once they get to that size it would be nearly impossible to exterminate because the smallest chunk of root would eventually sprout another one.
So many ideas here. Definitely food for thought.
So yesterday I’m out in front of my house, transferring the last of a huge pile of wood chips from the street level to above the retaining wall. Laughing to myself … “why the heck did I post that thread? I’ve got piles of woodchips several feet deep in places here…it’s going to be months or maybe not until next season that I can even think of planting anything here”.
I have a 24’ x 3’ strip of ground on the south side of my garage … maybe that will be a better place for a mix of rhubarb and bocking 14 comfrey.
I think smaller plants and herbs under the trees … low commitment type stuff … might make more sense.
Have you ever heard of food forests? They are a type of permaculture and are really fun to grow. They center around creating “guilds” of other beneficial plants around fruit trees.
If interested, check out Parkrose Permaculture on YouTube. Angela has been growing her food forest for 12(?) years in Portland, OR so she may have insightful info for you!
Have you seen high end fashion shows? Outlandish designs that you wonder “who the hell would wear that and where?” They are meant to be ‘inspirational’. If you look at the designers actual lines you see elements of those designs on the stuff they actually sell. At the risk of offending people I will say permaculture is just like that; highly inspirational with good ideas to incorporate but as a pure system? Impractical as they come.
The idea that you can create a natural forest that you can just walk through and leisurely pick fruit as it ripens with little effort to boot is a myth. It takes a whole lot of effort to implement and more to maintain. In my area birds would strip every single berry, and that is if moose didn’t come first to mow everything down. Our weeds are perennials like cow parsnip that could not care less about being ‘suppressed’ by ground cover, they would grow 8 feet tall and do the suppressing themselves.
I do buy into the whole system of zones and minimizing wasted effort by having things flow like blood through veins in a body. Also on having variety growing together, as opposed of monoculturing; very few of my bushes of the same type are grown next to each other. This promotes such biodiversity that by the time I find a pest chances are I find something eating them.
I recently encountered that word “guild” and didn’t know what it was referring to … thought it had something to with farming co-op or extension service. lol.
Not really worth an argument, and it looks like @erics_tiny_orchard has moved on from the idea of interplanting rhubarb. But, to keep the record straight, what you’re showing is not a taproot, but the woody rhizome that forms the crown of the rhubarb. And, those pieces of root from outside the crown will not spread rhubarb far and wide. It is easily propagated by division of the crown, but only of the crown, not of the peripheral roots. It is very easy to contain, and not at all hard to kill.
Rhubarb does have a reputation as you say as a “voracious” feeder. But most of what it “eats” is recycled back into the soil ecosystem, unless you are agressively carting off leaves and stalks. As I said before I grow it almost entirely by mulching and ignoring it. Never fertilize it. The ones we’ve kept for our own use have been “in the family” for 40 years, and never fertilized, other than the mulch.
i use a modified version of a food forest. not a true food forest but looks kind of similar. some of it works some of it doesnt in a true food forest but so far my version has worked but im not a permie purest by any means.
