Certain plants avoid rhubarb garden spots for good reason. The worst offenders are curly dock, sunflowers, and walnut trees. Each one causes problems from pest attraction to root toxins that stunt your rhubarb. Keeping these plants far from your patch will save you a lot of trouble. Know the bad players and your rhubarb will grow stronger every year. The good news is that most common garden plants get along fine with rhubarb.
Smart rhubarb companion planting starts with knowing which plants make good neighbors. UW-Madison Extension lists great pairings: Husker Red penstemon, tall garden phlox, and tall bearded iris. Feather reed grass works well too. These plants look great next to rhubarb's big leaves and they won't steal nutrients. They also attract good insects that help keep pests in check around your patch. All of these options add color and height without stealing water or food from your rhubarb crowns.
On the flip side, the bad neighbors for rhubarb can cause real damage if you don't catch the problem early. Curly dock tops the list because it serves as the main alternate host for the rhubarb curculio beetle. This fat, gray beetle bores into rhubarb stalks and crowns, leaving holes that invite rot and disease. Sunflowers pull heavy amounts of nutrients from the soil and cast shade that rhubarb doesn't want. Walnut trees push a chemical called juglone out through their roots. This toxin can kill or stunt rhubarb within the drip line of the canopy.
I found out about the curly dock connection the hard way in my own garden. A patch of dock had spread along the fence about 30 feet from my rhubarb bed. That same summer I started noticing small holes drilled into my thickest stalks. The damage got worse each week until I looked it up and found the curculio beetle link. Once I pulled every dock plant within sight, the beetle damage dropped off within one season. That single weed removal made a bigger difference than any spray I'd tried before. I check for dock regrowth every month now as part of my routine garden walk.
Spacing matters just as much as choosing the right plant partners. Give your rhubarb at least 3 to 4 feet of clear ground between it and any neighbor plant. Rhubarb crowns spread wide over the years and they don't like being crowded. Tight spacing traps moisture around the stalks and invites fungal problems you don't want to deal with. If you have walnut trees on your property, plant your rhubarb at least 50 feet away from the trunk to stay outside the juglone danger zone.
Pull up every curly dock plant you can find within 50 feet of your rhubarb patch. Get the whole root because dock grows back fast from any piece left in the soil. Check for new dock seedlings every few weeks during the growing season since the seeds spread far and sprout fast. This one step cuts your curculio beetle risk more than anything else you can do. Stay on top of dock removal and you won't need to worry about this pest.
Pick your rhubarb's neighbors with care and give it plenty of room to grow. The right companion plants add beauty to your garden while the wrong ones bring pests and problems. Keep dock, sunflowers, and walnuts away from your patch and your rhubarb will stay healthy for years. Once you know which plants avoid rhubarb garden spaces, keeping a clean patch becomes second nature. A little planning up front saves you from fighting pest and disease issues down the line every growing season.
Read the full article: Growing Rhubarb: Expert Advice for Success
