How to make rhubarb garden spray

How to make rhubarb garden spray

The same high concentration of oxalic acid in rhubarb leaves that makes them too toxic for humans to consume is equally devastating to aphid populations on roses and other prized plants. If you grow rhubarb plants (Rheum x cultorum) or have access to other rhubarb leaves that weren’t sprayed with chemicals, then you can make an organic, low-cost, aphid insecticide. Rhubarb is hardy in U.S. Department of Agriculture plant hardiness zones 3 to 8.

Select three or four large rhubarb leaves that weren’t sprayed with chemicals. Pinch the leaves from the stalks of rhubarb growing in an organic garden, or cut them from the stalks of store-bought, organically grown rhubarb.

Put the rhubarb leaves on a cutting board, and chop the leaves roughly.

Place 4 cups of water in a medium-size glass, ceramic or stainless-steel saucepan. Boil the water in the saucepan by using a stove-top burner.

Put 2 cups of the coarsely chopped rhubarb leaves into the boiling water. Turn down the burner’s heat, and simmer the rhubarb leaves for 30 minutes in the water.

Remove the saucepan from the stove top, and allow it to cool.

Strain the rhubarb mixture into a bowl or pitcher, pressing the rhubarb leaves in the strainer to extract all of its compounds. Afterward, the bowl or pitcher will contain a rhubarb leaf infusion.

Mix 1 teaspoon of liquid dish soap with 2 1/2 cups of cold water in a container.

Blend the rhubarb leaf infusion with the soapy water. Pour the resulting rhubarb solution into a clean spray bottle. Reserve leftover solution in a tightly capped jar.

  • The Complete Book of Herbs; Lesley Bremness
  • Cornell University: Growing Guide — Rhubarb
  • Spray the rhubarb solution on affected plants thoroughly, paying special attention to both sides of leaves. A windless evening is the best time to use the spray because that timing avoids disrupting daytime pollinators such as bees and butterflies. Spray affected plants every two to three days until the aphid infestation appears to be controlled.
  • Don’t spray the rhubarb solution directly on plant parts you will eat, such as lettuce and spinach leaves. Although the diluted solution probably won’t produce serious consequences, even small amounts of oxalic acid are enough to cause illness and nausea in some people. If you spray the non-edible foliage of vegetable and fruit plants with the solution, wash those plants’ edible portions thoroughly before ingesting them.

Ellen Douglas has written on food, gardening, education and the arts since 1992. Douglas has worked as a staff reporter for the Lakeville Journal newspaper group. Previously, she served as a communication specialist in the nonprofit field. She received her Bachelor of Arts from the University of Connecticut.

Rhubarb is an intriguing plant, with edible red stalks and a poison in every large, green leaf. The stems are traditionally used as an ingredient in desserts, but have an even wider range of cooking uses. The leaves, however, kill. The poison in the leaves is oxalic acid, which will stop the human heart if ingested. However, the leaves can also be used to make a natural pesticide that breaks down quickly and disposes of many unwelcome bugs without inhibiting the presence of beneficial bees. Below are two ways to use rhubarb leaves to protect your garden from insects.

Rhubarb Spray

  • 1 cup rhubarb leaves
  • 6.5 cups water
  • ¼ cup liquid dish detergent or soap flakes
  • 1 large pot
  • A spray bottle

Step 1: Place the rhubarb leaves in the pot and cover them with the water.

Step 2: Boil the water and leaves for 20 to 30 minutes. Then remove the pot from the heat and let the contents cool.

Step 3: Strain the resulting liquid into a spray bottle. Dispose of the boiled leaves.

Step 4: Add the dish detergent and mix the liquid well.

Step 5: Spray the resulting liquid on your plants to kill aphids and other disruptive insects. However, do not use rhubarb spray on food bearing plants. The poison will break down quickly, but there is still a risk that the sprayed food will have oxalic acid on them.

Step 6: The rhubarb spray will rot, so use it quickly or freeze the mixture to store it. If you store it, be sure to accurately label it as poison.

Note—When choosing a soap to add to to your rhubarb pesticide spray, avoid harsh detergents and soaps with a long list of chemicals. The chemicals will damage your plants and contaminate your garden soil. There are garden soaps and biodegradable soaps available that will protect your plants from insects without causing further harm. Also, using a spray of just soap and water can be a useful pesticide.

Rhubarb Leaf Protectors for Seedlings

Step 1: Save rhubarb leaves when harvesting your rhubarb.

Step 2: Slit the rhubarb leaf along the fleshy central vein to create an opening.

Step 3: Place the opening in the leaf around the young seedling you wish to protect. The leaf will provide shade to the soil, retain moisture, and provide nutrients while decomposing. These function are in addition to the work the oxalic acid will do repelling insects.

Step 4: The leaf should decompose in 3 to 4 weeks. By that time, your seedling will be strong enough to survive on its own. If further insect repelling is needed, use the rhubarb spray described above. However, while the rhubarb leaf protector can be used on food-bearing plants, the spray cannot.

How to make rhubarb garden spray

By CameronB83 Follow

How to make rhubarb garden spray

How to make rhubarb garden spray

How to make rhubarb garden spray

Rhubarb is one of my favorite edible plants because of its delicious flavor in all sorts of foods. For those of you who do not know, you eat only the stalk of rhubarb and throw the leaves away. I’d always wondered if there was something I could be doing with those leaves instead of just throwing them away so I was very happy when I came across the idea to make a pesticide with them. Anyone who has gardened before knows how irritating it can be when insects or other pests ruin or destroy your plants. As I didn’t see any other Instructables on how to make a pesticide from rhubarb I figured I’d share my method. This spray is organic (as long as your rhubarb is) and it actually kills insects instead of repelling them.

IMPORTANT: Rhubarb leaves contain high amounts of oxalic acid which is toxic if consumed. This is why it works as a pesticide and it is also why you should keep the spray away from small children and pets. You shouldn’t use it on edible plants when you are going to eat the entire thing (lettuce, spinach, etc.). If you are going to use it on edible plants I’d say try to spray them before they start producing whatever part you are going to eat and wash it afterward.

Step 1: Preparing the Leaves

After you’ve used the stalk of the rhubarb for whatever you want, save the leaves instead of throwing them away. Cut them all into pieces about 1-inch square. After you’ve cut them, clean the cutting board or whatever surface you cut them on so there are no traces of the harmful acids.

Step 2: Boiling the Leaves

Measure the leaves you just cut. For every cup of leaves, boil one cup of water in a pot. Once the water is boiling, add the leaves all at once. As soon as they are in the water, turn the heat to low. Leave the pot on the stove for 25 minutes allowing the leaves to simmer.

Step 3: Finishing Up

After 25 minutes has passed, strain the leaves out of the water. I found a good way to do this was to wrap an old cloth (cheesecloth would work fine) around the top of a plastic cup. I then took a second plastic cup and put the first into it. The second cup helps to hold the cloth in place as you pour the spray into the cup. After all the leaves are collected on top of the cloth, bundle it up and squeeze it out to get all the pesticide into the cup.

The liquid you now have is concentrated and can be stored once it cools

IMPORTANT: Label the container you use with something that will tell others it is toxic

Step 4: Using It

Mix the concentrated solution with water in a ratio of 1:2 respectively. Put this in a spray bottle and it is ready to use.

As I stated earlier be sure to keep this away from small children. If you are going to use this on edible plants consider what parts are going to be eaten. If you know your pets chew on your plants make sure they cannot reach them after you spray them.

Thank you for reading my Instructable! If you want to see more of my projects subscribe to my youtube channel here.

Rhubarb leaves contain oxalic acid which can not only stop your heart but makes a great natural pesticide for leaf eating insects. If plant lice (aphids) or other insect pests attack your plants, the acid in the rhubarb leaves should work to suffocate and otherwise disturb them.

Also Know, how do I get rid of aphids on rhubarb? To make a aphid killing, natural, poisonous spray take about 8 to 10 rhubarb leaves, cut them small enough to fit in a saucepan and boil in water for 20 – 30 minutes. What you are doing here is extracting the oxalic acid from the rhubarb leaves.

Simply so, what can I make with rhubarb leaves?

  • Shine pots and pans. Oxalic acid is an active ingredient in products like Bar Keepers Friend, a non-abrasive powder that cleans and shines stainless steel and other surfaces.
  • Repel pests from leaves of non-edible plants.
  • Get crafty and use them to make stepping stones.
  • Use them to create a green dye.
  • Compost them.

How do you make oxalic acid from rhubarb leaves?

Distilling the oxalic acid from rhubarb leaves into water and then adding calcium carbonate in the form of precipitated chalk will cause the oxalic acid to form into oxalate crystals, which can then be strained from the mixture. With a digital scale, find the combined weight of your rhubarb leaves in grams.

Do you remember the “telephone” game? You might have played it when you were a kid.

In the game, one person whispers a message into the ear of the person next to him or her, then that person repeats the message to the person next to him or her and so on. By the end of the communication chain, the person announces what he or she heard.

Often, the last person in the line received a message that had little to do with the first message.

I experienced something like the telephone game last week, except this time, social media in the form of Facebook served as the “telephone.” As with the telephone game, by the time the message reached people and was repeated, it was a bit distorted.

All eyes were on rhubarb after the cold temperature blast. I had no idea people liked rhubarb this much.

I received phone calls, emails and questions via Facebook. People were talking about the avalanche of rhubarb information on their Facebook news feeds. Some people thought I had launched the “great toxic rhubarb campaign of 2015.”

“I didn’t do it,” I said when someone asked.

Some parts of North Dakota and other states had experienced untimely freezing temperatures. According to a widely circulated Facebook post launched in another state, rhubarb could become toxic (poisonous) after a frost. Could that be true?

According to the post, a hard freeze drives the naturally present toxin, oxalic acid, from the leaves into the rhubarb stalks.

I hadn’t nabbed any rhubarb from either of my neighbors, but after all this concern about rhubarb, I felt compelled to check out their rhubarb crops. Upon investigation, the leaves were not curled or discolored, and the stalks looked reddish green and ripe for making into cobblers, pies and other treats.

I grabbed a few stalks and we enjoyed the dessert recipe included with this column.

While at work, one of my students poked her head in my office and mentioned that someone in her apartment building was pulling up all her “poisonous rhubarb.” I was a little alarmed because I have a soft spot for rhubarb. This poor, defenseless, innocent rhubarb was reminding me of my childhood.

As a kid, I enjoyed bringing a cup of sugar to our garden and pulling a rhubarb stalk and dipping it in sugar. I wasn’t a food safety specialist back then, so I may have rinsed the rhubarb under a garden hose if my mother was looking.

When do you have to worry about rhubarb? Rhubarb in your garden that has frozen to the point where the stalks become damaged or mushy should be discarded. Check the leaves, too. If the stalks are firm and upright and the leaves have little damage, the rhubarb is OK. Discard the damaged ones and enjoy the stalks that grow later.

As with anything, when in doubt, don’t eat it.

Consuming large amounts of oxalic acid could affect your heart, digestive system and respiratory system. According to some sources, a person would need to consume 11 pounds of rhubarb leaves to reach a fatal dose.

During the World War I food shortages, people were encouraged to consume rhubarb leaves as a vegetable. That was not a good idea because oxalic acid is found in abundance in the rhubarb leaves. Rhubarb stalks naturally contain a very small amount of oxalic acid.

The usual issue of concern with oxalic acid-containing foods is the production of calcium oxalates in our body, which comprise kidney stones.

Heed the earlier warning: Do not eat any rhubarb leaves and you will be fine.

Have you ever heard the expression “the dose is the poison?” Many vegetables, especially leafy greens such as spinach, swiss chard, beet greens and cabbage, also contain small amounts of oxalic acid. If you eat the recommended amount of vegetables, you are consuming some of this natural chemical.

Please do not stop eating your vegetables, by the way.

Vegetables do not contain enough oxalic acid to warrant concern unless a person has a rare medical condition. If you have this condition, your health-care provider probably will refer you to a dietitian for help in knowing what foods to limit or avoid.

As I was talking about rhubarb and cold temperatures, someone overheard me.

“So you shouldn’t freeze your extra rhubarb because it will become toxic?” she asked.

The game of “telephone” was getting worse by the minute.

“You can freeze rhubarb in your kitchen for next winter,” I replied. “Just rinse it, cut it and freeze it in a single layer on a cookie sheet and pop it in a freezer bag,” I added.

Rhubarb provides vitamin C, fiber and lots of tart flavor in a wide range of recipes. Botanically, rhubarb is considered a vegetable, although we may think of it as a fruit because it is served in sweet desserts.

Enjoy some delicious rhubarb this season. Remove the leaves and discard them. Be sure to rinse rhubarb thoroughly under cool, running water.

Visit for more information about food preservation and more recipes.

I was so inspired by all this discussion that I bought a rhubarb plant to plant in our garden. Here’s one of the first recipes I learned to make from the rhubarb that my grandmother planted in the yard of my childhood home about 100 years ago. That was right around the time of World War I when people were advised to eat rhubarb leaves. My family must have ignored the recommendation.

1 1/2 c. brown sugar

1 3/4 c. cut-up fresh or frozen rhubarb

Topping (1/4 c. sugar and 1/2 tsp. cinnamon)

Preheat the oven to 350 F. Cream sugar and butter. Add egg and buttermilk; mix thoroughly. Sift flour, soda, salt; add to sugar-buttermilk mixture. Add vanilla and rhubarb. Pour into greased and floured 9- by 13-inch pan. Sprinkle topping over batter. Bake for 40 to 50 minutes, until a knife comes out clean.

Makes 12 servings. Each serving has 260 calories, 4 grams (g) of protein, 9 g of fat, 41 g of carbohydrate, 1 g of fiber and 230 milligrams of sodium.

How to make rhubarb garden spray

Rhubarb leaves are poisonous to humans, but a strong rhubarb leaf brew is great for your plants. Perfectly suitable for an organic garden, a concentrated rhubarb liquid can be used as a natural fertilizer or a safe pesticide spray.

  • Strengthen your plants: Use the brew to help your plants grow and make them more resilient. Your plants will enjoy a growth aid in the spring, and a strength booster again before winter.
  • Prevent potassium deficiency: Leaves of the rhubarb plant contain a lot of potassium, which plants need. Potassium deficiencies make plants more susceptible to diseases.
  • Use as a remedy in case of diseases: Rhubarb leaves can help if your plants are already sick. In case of blight, remove the affected parts of the plant and spray the unaffected parts with a high-concentrate brew. This remedy may also help to get rid of aphids.

Another useful remedy: Homemade Weed Killer from Organic Ingredients

Making a Concentrated Brew

How to make rhubarb garden spray

To make a brew out of rhubarb leaves, you’ll need a pot, a strainer, and a tea towel. A watering can or a spray bottle will come in handy when it’s time for application.

For use against disease infestation: use 1 part water to 1 part leaves.
To use as a fertilizer: use 5 parts water to 1 part leaves.

  1. Use a sharp knife to chop the leaves into small pieces.
  2. Add the chopped rhubarb leaves and water to the pot and bring to a boil.
  3. After about one minute, turn off the heat and let the rhubarb leaves steep for 30 minutes.
  4. Filter the liquid through a sieve. Squeeze the leaves with your hands or with the help of a tea towel.
  5. Toss the rhubarb leaves in the compost pile.

Another method is to put the leaves in a sealable container with warm or hot water. Place the lid on and let the brew infuse for 24 hours.

Note: This brew will keep in the refrigerator for a few days. It is best to use it up quickly to avoid fermentation. You can also freeze it, but be sure to label it as poisonous before putting it in your freezer.

How to make rhubarb garden spray

Plastic freezer bags or containers made of plastic aren’t the biggest sustainable hit nowadays. Here are some sustainable plastic-free alternatives…


  • As a fertilizer or disease prevention: Water your plants with your rhubarb leaf brew during their growing season. Keep in mind that harvest time for rhubarb is spring/early summer.
  • To fight plant diseases: Spray the affected plant with the rhubarb leaf brew once a day for about three days in a row.

Tip: Don’t use the brew on any plants that are food bearing.

Do Rhubarb Leaves Belong in the Compost Pile?

While rhubarb leaves aren’t safe for human consumption, there’s no reason not to add them to your compost pile! The oxalic acid has seemingly no effect on soil microorganisms and is not absorbed by plant roots. This means that plants grown in rhubarb-leaf compost are also safe to eat.

This article has been translated from German to English by Karen Stankiewicz. You can find the original here: Nicht wegwerfen! So kannst du Rhabarberblätter verwenden

How to make rhubarb garden spray

If you are looking to save money in the garden, then one easy way to cut costs is to make your own bug and insect sprays. Not only it is it less expensive, but it is healthier too. Most store bought bug sprays are full of toxic chemicals that it is best to avoid.

This post may contain affiliate links.

Bug Spray #1 — Cayenne Pepper

  • 8 c. water
  • 1 c. Dawn liquid dish soap
  • 1 c. Listerine mouth wash
  • 1 tsp. cayenne pepper

Mix together the above ingredients in an empty gallon sized orange juice or milk container.

Pour some of it into an empty spray bottle and apply to plants as needed.

It is best to spray it in the morning, before the plants are hit by direct sun, which may cause burning due to the alcohol contained in this mixture.

Bug Spray #2 — Liquid Dish Soap

  • Liquid dish soap
  • Water

This is a variation of the first recipe, but contains only water and dish soap. This spray is particularly effective for controlling aphids in the garden.

Fill an empty spray bottle half way with water. Add a couple of squirts of dish soap and then fill the bottle the rest the way with water, shaking gently to mix.

To apply to plants, spray liberally to the tops and bottoms of leaves that are infested with aphids.

Re-apply weekly until aphids are gone. You may have to apply more often if there is a lot of rain to wash the soap off of the leaves.

Bug Spray #3 — Hot Peppers

  • 1/2 c. hot peppers, chopped
  • 2 tbsp. dish soap
  • 2 c. water

Puree peppers and water in a blender or food processor. Let it sit in the refrigerator overnight. Strain through a fine mesh sieve.

You might want to wear rubber gloves while doing this, because the hot peppers will be absorbed into your skin and can cause burning. Also keep it away from your eyes.

The next day mix in the dish soap and put the mixture in a spray bottle. Add water. Apply to bug infested plants as needed.

How to make rhubarb garden spray

Bug Spray #4 — Rubbing Alcohol

  • 1 c. rubbing alcohol
  • 4 c. water
  • 1 tsp. vegetable oil

Mix all ingredients together into a spray bottle and apply to plants as needed.

Bug Spray #5 — Lemon Peels

  • 2 c. lemon peels
  • 4 c. water

Bring water to a boil. Remove the pan from the heat and add the lemon peels. Cover and let the lemon peels set in the hot water until the water cools.

Strain the mixture and pour the lemon water into a clean, empty spray bottle. Use to treat plants infested with white flies.

Helpful Tips

When you make your own bug sprays, you still need to test them on a small area of your plants first to make sure they will not harm your plant in any way.

It is possible for some of the ingredients to affect plants differently. Try applying the mixture weekly and see if it is working. Applying too often will also harm your plants.

Do not apply if it looks like it is going to rain soon, because the rain will wash away the spray you just applied. For best results, try to apply on a clear, dry morning.

Related Gardening Hacks

Follow my gardening board on Pinterest.

How to make rhubarb garden spray

How to make rhubarb garden spray

In case you missed it:

4 Comments on “5 DIY Bug Sprays for the Garden”

Hi Rachel, I love your site, very informative. I have been looking for plant bug sprays for some time and wish to try your suggestions. When you refer to liquid measurements using the letter ‘c’ does this refer to liquid centilitres?

Hi! No, the “C” refers to cups.

I have holes on my Dahlia leaves. Obviously something is eating them. I don’t like to use store boughten bug sprays to many chemicals in them. Do you have any suggestions for solving my problem?

Thanks for sharing !

Leave a Reply Cancel reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

I love making probiotic sodas at home. It’s fun and easy, and it’s cool to be in control of how sweet, how fizzy or how tart is turns out. One of the first sodas I made was Elderflower Soda, and after that success, I made a quick batch of Rhubarb Soda, and it was also a hit. Now that it’s almost spring, it’s Rhubarb Season again, so I whipped up the first batch of the year, this time using local honey as well. It’s kind of like lemonade, with a rosy flavor– so nice! Plus… Probiotics! What a nice way to get some more into your family. As with most home fermentation projects, this formula is flexible.

How to make rhubarb garden spray

How to Make Rhubarb & Honey Soda (With Lacto-Fermentation!)

How to make rhubarb garden spray

5 from 1 reviews

This Rhubarb Soda is kind of like a sparkling lemonade, with a rosy flavor– so nice! Plus… Probiotics! What a nice way to get some more into your family. As with most home fermentation projects, this formula is flexible.

  • Author: ariana


  • Rhubarb– I used 6 stalks
  • Raw, local honey (or at least raw– you can order it here if you need to) And yes, you can also use sugar instead.
  • Some kind of culture– you can use (homemade) sauerkraut juice or whey from strained yogurt– you only need a tablespoon or two
  • a demijohn, an airlock, a funnel and swing-top bottles.


  1. Chop the rhubarb into 1/2 pieces and put in a pot.
  2. Cover the rhubarb in the pot with water, and bring to a simmer. I used about a liter of water.
  3. Simmer until the rhubarb is very tender, then cool. I left mine overnight to steep, but you probably don’t need to.
  4. Strain out the rhubarb. (When I stirred mine with a spoon, it disintegrated, making something like applesauce. I added honey and now we have a nice rhubarb compote.)
  5. Add the honey and stir until dissolved. I used about 3/4 cup, which made it very, very sweet. Keep in mind that the sugars will be digested to create the fizz, so you do want to start with it much sweeter than you would like the soda to be. Dilute the syrup with water if it comes on too strong (super tart, since it will get more sour as it ferments.)
  6. Pour the “juice” into a sterilized demijohn, add your whey or sauerkraut juice and add your airlock.
  7. Let it sit for about three days, and taste it. Mine fermented pretty quickly, but there are some variables– the temperature of the room, the strength of the culture you used, etc. Taste it and let it ferment until it’s only a little sweeter than you would like it to be.
  8. Pour it into your swing-top bottles, and store in the fridge. You could leave them out at room temperature if you’d like to drink them sooner, but I usually pop them into the fridge to slow down the fermentation process. You will want to drink them within a week, or risk losing most of your Rhubarb Soda to the “geyser effect.”


Your beverage will get drier, more tart and fizzier the longer you wait. It will eventually develop more of an alcohol content, too, so you might want to taste it before giving it to your kids if you’ve been storing it for a while!

Did you make this recipe?

Share a photo and tag us — we can’t wait to see what you’ve made!

We enjoyed our Rhubarb Soda this weekend– it was nice and sunny, and we did a lot of work outside. It is rosy, tart and so refreshing– and not to mention the pleasures of drinking something pink. Plus, there is something really exciting about making your own intense carbonation, naturally. That always gives me a thrill. I hope you’ll try making some– it’s really very easy, and you can’t buy anything like it!
For more fermented beverage projects, you may want to check out these books: True Brews and Real Food Fermentation. Want to make something a little more grown-up than soda? We love Rhubarb Wine!