Learning how to make rhubarb syrup takes one small pot and about twenty minutes. Rhubarb syrup is a tart, rosy-pink syrup made by simmering chopped rhubarb stalks with sugar and water until the stalks collapse and go pale, then straining the liquid into a bright, tangy, blush-pink pour. Spoon it into sparkling water, iced tea, lemonade, cold brew, cocktails and spritzes for a garden-fresh lift of tart fruit.
This is the sharp, garden-fresh cousin of the fruit syrups on the coffee bar. The plain sweetener underneath it lives in how to make simple syrup, and the wider family of flavours is mapped out in coffee syrups explained. Here we stay with the rhubarb itself: how to coax out its tang and that signature pink, and how to deepen both if you like.
What rhubarb syrup is
Rhubarb syrup is a simple syrup infused with rhubarb stalks. The flavour is sharp, tart and unmistakably garden-fresh, with a faint berry edge, closer to sour green apple than to any candy version. Because rhubarb is genuinely tart, the syrup needs a good amount of sugar to balance it; taste as you go and let the sweetness settle the sourness rather than bury it.
Rhubarb's colour is a little unpredictable. Deep-red stalks give a rosier pink; greener stalks make a paler, more golden syrup that tastes just as good but looks shy. If you want a more vivid blush and a rounder flavour, drop in a few raspberries or a strip of orange zest as it simmers. The raspberries push the pink and add berry depth; the orange zest warms and rounds the tartness. Neither changes the method, they just tune the colour and the edge.
One firm rule sits behind all of this: use only the stalks. Rhubarb leaves are not edible, so trim them off and discard them, and cook only the pink-to-green stalks.
How to make rhubarb syrup: the method
The whole idea of how to make rhubarb syrup is to simmer chopped stalks in a sugar syrup just until they collapse and surrender their juice and colour, then strain the liquid off before it stews down to jam. Chop the rhubarb small, about half an inch (roughly 1 cm), so it breaks down fast and evenly. Bring it to a gentle simmer and watch it: as the stalks go soft and pale, the liquid turns pink. That is your cue.
Keep the heat low and stop early. Once the stalks have gone limp and the syrup is coloured, pull it off the heat, because pushing it too far gives a cloudy, cooked, jammy compote instead of a clean pour. When you strain, let it drip through the sieve on its own or press only lightly; crushing the soft pulp hard forces fine solids through and clouds the syrup. A clear syrup mixes into drinks better, while a slightly pulpy one is fine for spooning over dessert.
Ingredients
- About 3 cups (roughly 350 g) chopped rhubarb stalks — fresh or frozen, cut into small pieces. Frozen works well and collapses even faster.
- 1 cup (about 200 g) sugar — plain white sugar keeps the colour clean, and rhubarb's tartness wants a generous hand.
- 1 cup (240 ml) water — roughly equal parts sugar and water make a classic pourable syrup.
- A few raspberries or a strip of orange zest (optional) — for deeper colour and a rounder flavour.
Treat the amounts as a starting point; the ratio matters more than the exact gram. Equal parts sugar and water gives a syrup that pours cleanly, and you can nudge the sugar up if your rhubarb is especially sharp.
Rhubarb syrup ratios and timing
Here is the whole recipe at a glance: a 1:1 sugar-to-water base carrying about three times its volume of chopped rhubarb, warmed only briefly. Scale it up or down, but keep the sugar and water in step with each other.
| Element | Amount | Ratio or role |
|---|---|---|
| Chopped rhubarb stalks | About 3 cups (roughly 350 g) | The flavour and the pink colour |
| Sugar | 1 cup (about 200 g) | 1 part sugar |
| Water | 1 cup (240 ml) | 1 part water |
| Gentle simmer | About 8 to 12 minutes | Stop once the stalks collapse and the liquid is pink |
| Rest off the heat | 5 to 10 minutes | Deepens flavour and colour before straining |
| Yield and keeping | About 1.5 cups (360 ml) | Refrigerate; use within about 2 to 3 weeks |
Step by step
- Prep the rhubarb. Trim off and discard the leaves and the dry stalk ends. Rinse the stalks and chop them small, about half an inch (1 cm), so they break down quickly.
- Warm the base. Combine the sugar and water in a small saucepan over medium heat and stir until the sugar dissolves and the liquid runs clear.
- Add the rhubarb. Tip in the chopped stalks, along with the raspberries or orange zest if using. Bring to a gentle simmer, not a rolling boil.
- Simmer just until soft. Let it bubble softly for about 8 to 12 minutes, until the stalks go limp and pale and the liquid turns pink. Stop before it cooks down to a thick, jammy mush.
- Rest off the heat. Take the pan off the heat and let it steep for 5 to 10 minutes so the flavour and colour deepen.
- Strain gently. Pour through a fine-mesh sieve set over a jug. Let it drip, or press only lightly; do not crush the pulp hard, or the syrup clouds. Save the soft cooked rhubarb for yogurt or porridge.
- Taste and balance. Rhubarb varies, so taste the warm syrup and stir in a little more sugar if it is too sharp.
- Cool and bottle. Let it cool to room temperature, then funnel into a clean jar or bottle and refrigerate.
Plain vs raspberry- or orange-boosted
| Version | Add | Colour | Flavour |
|---|---|---|---|
| Plain rhubarb | Just rhubarb, sugar and water | Soft blush pink to pale gold, depending on the stalks | Sharp, tart, garden-fresh with a faint berry edge |
| Raspberry-boosted | A small handful of raspberries | Deeper, more vivid rosy pink | Rounder and fruitier, with clear berry depth |
| Orange-boosted | A strip of orange zest | Warmer, slightly golden pink | Rounder and mellower, tartness softened by citrus warmth |
How to use rhubarb syrup
Rhubarb syrup is bright and tart, so it lifts almost anything cold. The classic is a rhubarb spritz: a spoonful over ice, topped with sparkling water and a squeeze of lemon, for a pink, refreshing long drink. Stir it into iced tea or lemonade for a tangy, rosy twist, or add a splash to cold brew and iced coffee, where its sourness plays against the roast. It shines in cocktails and mocktails too, from a rhubarb gin fizz to a spritz with sparkling wine or a simple soda. Start with about a tablespoon per glass, taste, and add more.
Because it leans tart, rhubarb sits naturally alongside the berry syrups. If you like it, the brighter, jammier raspberry syrup is the obvious next one to make, and the two are lovely stirred together.
Storage and safety
Keep rhubarb syrup in a clean, airtight jar or bottle in the refrigerator and use it within about two to three weeks. Because it is made with fresh fruit, it does not keep like a plain simple syrup, so pour rather than dipping a used spoon into the jar, label it with the date, and give it a look and a sniff each time. If it turns cloudy, smells off or grows any fuzz, throw it out. To keep extra for longer, freeze it in small portions or an ice-cube tray and drop a cube straight into a cold drink whenever you want one.
On safety, the one thing to remember is that only the stalks are used: rhubarb leaves are not edible, so trim and discard them and cook only the stalks. Beyond that, this is simply a food-and-drink recipe with no health claims attached; responses vary, and this is not medical advice. And never add honey to a drink for an infant under twelve months.