Peanut Butter Shrub invading my vegetable beds - Ask Extension
Hi~ hope you are well. We were gifted a peanut butter shrub (harlequin glorybower, Clerodendrum trichotomum) about four years ago. We really liked it ...
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Peanut Butter Shrub invading my vegetable beds #769839
Asked August 30, 2021, 12:55 PM EDT
Hi~ hope you are well. We were gifted a peanut butter shrub (harlequin glorybower, Clerodendrum trichotomum) about four years ago. We really liked it but didn't realize it sends up suckers until we built raised vegetable beds near it, because they got mowed before we noticed them.
Last month we chopped the tree down and of course are still finding those suckers in the beds. I pull out several every week.
I didn't want to use any kind of stump killer or anything else to help kill the suckers and I am just dealing with them now but pulling. My concern is, are these trees allelopathic? I have established and happy squash where they are coming up now, but they are getting so clever and shooting farther out toward some freshly seeded areas (I garden over winter and a hoop house goes over the beds infected by this tree in the winter.)
One other question: if a shoot appears near a delicate seedling, like a carrot or what have you, can I just cut the shoot to the soil surface rather than yank it out?
Is this tree poisoning my bed? I am so sorry for all the questions, but when I have asked online people get super defensive about these trees (those flowers and berries really are so beautiful and I wish they weren't so problematic.)
Thank you for reading this long message.
Dena
Multnomah County Oregon
Expert Response
Hi, Dena,
I have not found any indication that Clerodendrum trichotomum is allelopathic, and in any case, it is pretty rare that allelopathy is really a problem in a garden - it's one of those concerns that is rather overblown. A much more likely problem is that the wide-ranging, well established roots of the shrub are stealing water and nutrients from your other plants. Every time a sucker comes up, it indicates more roots growing underground.
As you have found, the roots will keep seeking out new territory and trying to grow by suckering. If you are VERY vigilant and keep pulling them up as fast as they grow, you may eventually exhaust them and they will die. This could take years. And yes, you can simply cut one off rather than pull it to protect a nearby seedling. This just means that it will re-sprout near the surface instead of below.
I know you would prefer not to use an herbicide, but in this case, to save your sanity if nothing else, I do recommend it. If you use a systemic herbicide such as glyphosate (roundup) carefully in the fall, it should be very effective. Ideally, apply it after you have completed your vegetable harvest, but while the Clerodendron is still trying to grow. Find every sucker you can, cut it off close to the ground, then paint full strength glyphosate on the cut surface with a small disposable brush or q-tip. This will prevent it getting on any other plants. Autumn is the best time for this.
Don't worry if people try to defend glorybower. The definition of a weed is, a plant that is growing in a place a person doesn't want it. There are no weeds in nature. For you, in this case, it is a weed, even though it is a lovely shrub in the right place.
I have not found any indication that Clerodendrum trichotomum is allelopathic, and in any case, it is pretty rare that allelopathy is really a problem in a garden - it's one of those concerns that is rather overblown. A much more likely problem is that the wide-ranging, well established roots of the shrub are stealing water and nutrients from your other plants. Every time a sucker comes up, it indicates more roots growing underground.
As you have found, the roots will keep seeking out new territory and trying to grow by suckering. If you are VERY vigilant and keep pulling them up as fast as they grow, you may eventually exhaust them and they will die. This could take years. And yes, you can simply cut one off rather than pull it to protect a nearby seedling. This just means that it will re-sprout near the surface instead of below.
I know you would prefer not to use an herbicide, but in this case, to save your sanity if nothing else, I do recommend it. If you use a systemic herbicide such as glyphosate (roundup) carefully in the fall, it should be very effective. Ideally, apply it after you have completed your vegetable harvest, but while the Clerodendron is still trying to grow. Find every sucker you can, cut it off close to the ground, then paint full strength glyphosate on the cut surface with a small disposable brush or q-tip. This will prevent it getting on any other plants. Autumn is the best time for this.
Don't worry if people try to defend glorybower. The definition of a weed is, a plant that is growing in a place a person doesn't want it. There are no weeds in nature. For you, in this case, it is a weed, even though it is a lovely shrub in the right place.
