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You just made some delicious rhubarb pie and are left with a pile of leaves. Apart from throwing them away, what can you do with them? Is it safe and possible to compost rhubarb leaves?
Composting rhubarb leaves is completely safe. Though they are unsafe for human consumption, rhubarb leaves will not damage a compost pile and will add large amounts of nitrogen to compost. However, you’ll want to keep leaves away from pets as they can be dangerous to cats and dogs.
Keep reading to learn more about how to compost rhubarb leaves, and the benefits rhubarb leaves can offer a compost pile, and other uses for rhubarb leaves around the garden.
Are Rhubarb Leaves Compostable?
Rhubarb leaves make a great compost. They’re broad and leafy, break down quickly, and disintegrate beautifully into a mix of green and brown composting matter. They can be thrown in whole or chopped into smaller pieces to break down faster.
Rhubarb leaves break down into a healthy compost that is easily used and enjoyed by a wide variety of plants, trees, bushes, and vegetables and can be especially beneficial for balancing out the health of native soil.
So why do some people balk at throwing rhubarb leaves into a compost pile? While rhubarb leaves make for excellent fertilizer, the leaves are toxic to humans and animals when consumed. They won’t hurt compost, but you should never eat them or mistake them for other greens.
What Makes Rhubarb Leaves Dangerous to Eat?
Rhubarb leaves contain very high quantities of oxalic acid
, which is dangerous and even lethal to humans if ingested. While the tasty rhubarb stems contain minimal amounts of this acid, the leaves are incredibly dense with it, making it highly unsafe to eat them.
So what are the symptoms of oxalic acid poisoning?
- Abdominal pain
- Chest pain
- Excessive drooling
- Oral pain
- Seizures and
- Vomiting
These are all comic signs of oxalic acid poisoning. This poisoning can begin within minutes of consumption and may also result in burns to the mouth, throat, and esophagus.
Some of these nasty side effects are not too unlike any other food poisoning, but this leaf’s capacity to cause severe burns to soft internal tissue is worrying. In addition, in some cases of oxalic acid poisoning from commercially concentrated sources, negative effects on the kidneys have also been observed.
While this has only happened a handful of times, rhubarb leaf consumption can also prove lethal. So, while you’ll want to avoid eating these leaves, are they safe for naturally occurring soil microbes?
Will Rhubarb Leaves Harm Microbes in Soil?
While oxalic acid will have devastating effects on human internal tissue, it won’t hurt soil bacteria, earthworms, or other creatures in your compost heap. This is because the acid breaks down rather quickly along with the leaves themselves and loses its potency as it does so.
The microbes in the soil are accustomed to breaking down acidic materials, and the rhubarb leaf will be injected and used up by soil microbes just like any other break leaf or green material.
Likewise, earthworms that live off of decaying matter can handle rhubarb leaves just fine. Earthworms are weirdly rigid compared to us, and their bodies can process broken-down acids quite well. As a result, they seem drawn to rhubarb leaves, at least as much as any scraps, and will enjoy having them to snack on.
What about plant life? Will rhubarb leaves have any negative effects on growing plants once you compost with them?
Can Plants Handle Composted Rhubarb Leaves?
Yes, composted rhubarb leaves are safe to use as plant food. The oxalic acid that makes rhubarb toxic to humans is not absorbed through a plant’s root system and will do nothing to hurt your flowers or vegetables.
You see, oxalic acid really can’t survive outside of a rhubarb leaf’s cell walls, and once the plant matter begins to wilt and decay, the harmful acids become neutralized and dissolve quietly into the soil.
And because rhubarb leaves break down quite quickly in a compost pile, there’s no risk of this residual acid harming a plant’s root system. Instead, the rhubarb leaf will decompose into the rest of the organic matter surrounding it, and all acids will be diffused safely.
This makes it great for your garden, soil, and the health of your fertilizer as it decomposes entirely.
How long will this decomposition process take?
How Long Will Rhubarb Leaves Take to Compost?
Rhubarb leaves compost very quickly, within a week if turned properly in your compost pile, and within two weeks if left to rot alone with no turning or added heat and moisture. This is comparable to the decomposition time of other broad, leafy greens such as lettuce, cabbage, and kale scraps.
Thanks to their quick breakdown time, Rhubarb leaves can help the compost find a balance between slower decaying materials, such as fruit peels and bark, and the more delicate leafy green materials. In addition, the rotting leaves keep your compost nice and hospitable for microbes and worms.
What’s more, a compost pile that is rotated often will tend to generate more heat and break down vegetable matter a bit faster. You’ll get some nice, rich green composting materials out of rhubarb leaves, which will add valuable nutrition to your compost.
So how, exactly, will rhubarb leaves benefit compost and garden soil?
What Benefits Do Rhubarb Leaves Bring to Compost?
Rhubarb leaves are naturally rich in calcium, potassium, and fiber. They can add large amounts of beneficial nitrogen to your compost pile. As a green compost material, rhubarb leaves break down quickly and help provide plenty of nutrition for your garden or flowerbed.
Rhubarb leaves are also rather large and contain high amounts of vegetable matter per leaf, making them a much more economical investment for your compost pile when compared to much smaller-leaved clipping or refuse.
Rhubarb leaves are also high in vitamin C, lending important nutrients to the soil while providing shade and food for the microbes and other small life forms that call our soil home. They won’t take up much room once decayed and are less problematic than tougher materials such as orange peels or cherry pits.
The acidic nature of rhubarb leaves can also help benefit plants that thrive in lower-pH soil.
Will Rhubarb Leaves Make Compost More Acidic?
Yes, rhubarb leaves will lend a touch of acidity to your compost heap. The oxalic acid found in rhubarb leaves will not harm microbes but will make the compost slightly lower in pH level. This will help make your compost a bit more acidic and can help even out the alkalinity of high pH-level soils, such as those rich in sand or clay.
Use this acidic compost in place of commercial fertilizers for an ecologically friendly burst of nitrogen into your garden. It’ll be safer for the ground and more natural.
This acidic compost can do wonders for growing a variety of vegetables and flowers in otherwise weak soil and helping plants thrive in mountainous or rocky climates. Which plants will enjoy rhubarb leaf soil the most?
Which Plants Will Benefit from Composted Rhubarb Leaves?
Plants that thrive in more acidic soil will love rhubarb leaf compost. It’s great for azaleas, hydrangeas, sweet corn, cucumbers, broccoli, blueberries, and cranberries. It also works well with Japanese maples, magnolias, and heather.
It can also help balance out the pH levels of alkaline soils to make them more hospitable to pH-neutral and acid-loving flowers and vegetables. Even better, as the rhubarb vegetable itself is a natural acid-lover, this rhubarb leaf compost can even help fertilize your next rhubarb crop.
Rhubarb leaves in compost pair great with brown compost materials such as tree bark, twigs, dead leaves, and sawdust. Your garden will love it, and it’s safe for all plants.
What about pets? Are rhubarb leaves safe for pets and other animals?
Are Rhubarb Leaves Safe For Pets?
Rhubarb leaves can cause serious illness and even death in domesticated and wild animals. The same oxalic acid that can poison humans can make pets seriously ill and even kill them.
While rotting leaves may not appeal to your pets, you’ll want to immediately cover your rhubarb leaves with compost and mix them thoroughly into the heap to keep them out of sight. This will prevent pets and wild animals from snacking on them and getting seriously ill.
If you were considering allowing your rabbits or guinea pigs to snack on rhubarb leaves, don’t! While rhubarb leaves may look tasty to an herbivore or a rodent, they’re still toxic and can kill small animals and make goats and sheep unwell. So never allow your pets or domesticated animals to feed on rhubarb leaves.
If they’re not good for people and animals, are there other ways you can use rhubarb leaves safely around the home and yard?
How Else Can Rhubarb Leaves Be Used?
Being broad and leafy, Rhubarb leaves can be used in several unique ways around your garden. Use rhubarb leaves as
- A natural weed barrier
- Natural cleaning solution
- Insect repellant
- Natural dye for fabric
As a weed barrier, you can simply lay down the large, flat leaves of rhubarb over any soil you’re seeking to cover and protect from weeds. Mind you, this is a temporary solution, as the leaves will break down fairly quickly, but rhubarb leaves can be used this way if your weed barrier only needs up for a week or so.
Boil the leaves for about 30 minutes. Then, strain them and allow the liquid to cool. You can use this orange-brown cleaning solution and insect repellant around the house to clean or in the garden on non-edible and non-crop plants to keep bugs away.
We don’t recommend using the insect repellent on plants you’re going to eat or cook with, as the toxins in the rhubarb leaves could find their way into the solution and cause illness if consumed. Instead, keep it for roses, shrubs, and other such plants.
The same liquid process can yield a natural dye that will look beautiful on undyed fibers, looking especially nice on wool. Rhubarb leaves will give you a pale golden to mossy green hue and is perfectly safe to wear.
Can Rhubarb Stalk Be Composted?
Yes, absolutely! Rhubarb stalk, the reddish part used to make rhubarb pies, can be composted. It will also release nitrogen and calcium into the earth but will break down a bit slower thanks to its tough, fibrous nature.
If you have some leftover rhubarb stalks or some stalks that have gone bad, feel free to toss them into your compost pile. They’ll break down nicely and will decompose faster if chopped into smaller pieces beforehand.
The stalks are also safe for passing animals to munch on and won’t have to be buried under heaps of matter to keep them away from wildlife and farm animals.
And, of course, you can always use rhubarb stalks to make a variety of foods such as pies, jams, cakes, tarts, rhubarb-infused apple sauce, relish, scones, cookies, ice cream, and sauce. It’s a versatile root that still tastes great in just about anything.
Conclusion
Rhubarb makes a beneficial and nitrogen-rich composting material and is safe to use with plants and vegetables. It breaks down within a week in a well-maintained compost heap and pairs well with brown compost.
Rhubarb leaves can be extremely toxic to humans and animals and should not be consumed. Make sure your rhubarb leaves are buried within your heap so that passing wildlife won’t snack on them. Never feed rhubarb leaves to rabbits, guinea pigs, sheep, or goats, either.
There are a few more uses for rhubarb leaf, including as a natural bug repellant in your garden, as a cleaner, and as a natural fiber dye. Simply shred the leaf, boil for 30 minutes, strain the vegetable matter, and use the liquid as you see fit. Just make sure you don’t use it to spray down plants you’ll be eating.
Sources
- https://occup-med.biomedcentral.com/articles/10.1186/1745-6673-7-17
- https://www.petpoisonhelpline.com/poison/rhubarb/
- https://www.tasteofhome.com/collection/grandmas-favorite-rhubarb-recipes/
