Rhubarb Cordial (Rhubarb Simple Syrup)

When it is rhubarb season I am always looking for more ways to use this delicious springtime treat. One of my favorite ways is to make a big batch of rhubarb cordial (rhubarb simple syrup)!

rhubarb cordial in a glass and bottle

What is Rhubarb?

Rhubarb (latin name rheum rhabarbarum) is, believe it or not, a vegetable! It is part of the buckwheat family. It grows in beautiful, colorful stalks with great big leaves on top. The stalks are eaten and the leaves are left for compost.

Rhubarb is sour but delicious and often used in pies, cakes, muffins, and in delicious syrup like this one!

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Is Rhubarb Toxic?

Nope! Well kind of. Rhubarb leaves are high in oxalic acid and should not be eaten by people or grazed/fed to animals. The stalks however are perfectly safe, even later in the summer.

Yes, you can absolutely harvest and eat rhubarb all summer. The oxalic acid does not travel down the stalks as some people have said. We’ll talk more in a minute about heavy harvesting later in summer is a bad thing.

When is the best time to harvest rhubarb?

Rhubarb is best harvested in the spring when the shoots are well developed but before it has had time to put on a seed head.

Harvest as much rhubarb as you want all spring, though I would advise not taking more than half a plant’s stalks at any given time. 

It is a misconception held by many people that you can only harvest rhubarb until the end of June, or until it puts out seed heads.

After that point people think it becomes toxic. This is not true.

The real reason to not harvest rhubarb later in the summer is because it stresses out the plant. If you take a couple stalks here and there all summer long it is no big deal. 

​The rhubarb plant needs a lot of time to build up its energy reserves for the following winter. If you harvest heavily later in the year, the plant expends energy it needs for winter survival.

rhubarb stalk

How to Harvest Rhubarb

You can harvest rhubarb any time of the day. Simply reach down as far as you can on the stalk, then pull up firmly. Some folks like to use a knife, but this leaves an open stalk end that can get moisture and other pests inside it. It is best for the plant to pull the stalks by hand.

Next, discard the rhubarb leaves by snapping them off the end of the plant. Toss them aside or in your compost pile. 

Ingredients for Rhubarb Cordial

  • Four Cups Fresh Rhubarb
  • 1 3/4 Cup Water
  • 1 Cup Sugar


  • Fine-Mesh Strainer or Cheesecloth
  • Jar and lid for Storage
  • Funnel
  • Three quart pot
  • Stirring Spoon
  • Measuring Cups
  • Ladle (optional)

How to Make Rhubarb Simple Syrup

Begin by collecting your rhubarb stalks as explained above. Wash them, then trim off each end.

To your stock pot add 1 cup of sugar to 1 and 3/4 cup water. Over medium heat, bring this to a boil. Stir frequently and reduce the heat if need be. You want the sugar to melt into the water but you don’t want to scorch it.

While that mixture is heating, chop the rhubarb. I like to slice it long down the middle, then chop the skinny pieces into bits. 

chopped rhubarb in a bowl rough and tumble farmhouse

Once the sugar is dissolved, add the chopped rhubarb into the liquid mixture. Bring the mixture to a low simmer and stir every once in a while. Let it simmer for about twenty minutes, until the rhubarb starts to fall apart and get mushy looking.

Using a fine mesh strainer or cheesecloth, strain the syrup into a bowl. 

You can discard the cooked rhubarb, snack on their sour sugary goodness, add them to a recipe, or feed them to your chickens as a yummy treat. 

Allow the syrup to come to room temperature.

Once cooled, use a funnel to put the cordial into a glass bottle or mason jar.

I have a handy bowl with pour spout handles, but if you have it in a regular bowl I would recommend using a ladle to scoop it into the funnel. 

Storing Homemade Rhubarb Syrup

Store the cooled syrup in mason jars or a sterilized glass bottle. This simple syrup recipe will keep in the fridge for up to one month. You can also freeze it and it will last for several months. 

If you choose to freeze it, I’d recommend freezer bags or mason jars. Make sure to leave plenty of head space (I’d say an inch and a half) if freezing in mason jars as it will expand when frozen. 

Variations on Simple Rhubarb Syrup

Honey as a Sweetener

If you’d prefer to use honey as a sweetener you absolutely can! Cook down the rhubarb in the water as previously explained. Strain the rhubarb water out, then stir in honey to taste.

Vanilla Bean

About ten minutes into the simmering process you can toss in half a sliced open vanilla bean. This will really give it a decadent flavor.

​Citrus Twist

If you’d like to make a more complex flavor, add in the zest and juice of a lemon or orange to the concoction when you add in the chopped rhubarb. 

rhubarb simple syrup pinterest

How to Use Your Rhubarb Syrup Recipe

Possibly my favorite way to use it is to fill a cup with ice cubes, then half with rhubarb syrup and half with sparking water or club soda. This makes an excellent mocktail.

You can also mix it into vanilla ice cream for a delicious rhubarb shake. 

If you are looking for something with a little sauce, why not make a rhubarb margarita or rhubarb mojito? 

Move over maple syrup! You can also cook this recipe down even further to get a thicker syrup you can pour over pancakes. 

Pour this into your milk kefir for a second ferment to make knock-out rhubarb kefir.

Lastly, a great way to use this syrup is as a gift! That beautiful pink color looks especially lovely in a glass bottle. 

​As you can see, this one simple recipe has a ton of uses!

Looking for more rhubarb recipes?


Jill MacKenzie, University of Minnesota. Growing Rhubarb in Home Gardens

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