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Finnish fermented lemonade, known as sima, is a lightly carbonated honey-and-lemon soda that’s been brewed in Finland for generations to celebrate Vappu, the Finnish May Day.
It takes five ingredients: lemon, honey or sugar, raisins, water, and an optional pinch of yeast. It ferments on the counter for 24 to 48 hours, then finishes carbonating in the fridge for another 2 to 4 days. The result is a bright, fizzy, very low alcohol drink that’s closer to a homemade lemon soda than a mead, and in Finland it’s traditionally shared with kids at Vappu.
Mead and honey wine have a long history in the Nordic countries, and sima is one of their quickest, friendliest descendants. Where most meads ferment for months or years, sima ferments for a single day on the counter and finishes carbonating in the refrigerator over a long weekend. The goal is bubbles, not alcohol, and the raisins floating to the surface tell you when the counter ferment is done. It’s an old-school drink that’s easy to make in a modern home kitchen.
Sima is the centerpiece of Vappu, Finland’s May Day festival, where it’s served alongside funnel cakes called tippaleipä as everyone emerges from a long northern winter to celebrate the return of warm weather. Spring comes late up here in Vermont too, so making a batch of sima at the start of May has become its own little tradition in our house. By the time the dandelions bloom, the first jar is fermenting on the counter.
This recipe is grounded in the version published in The Nordic Cookbook by Magnus Nilsson, with technique refinements I’ve worked out across six or seven years of making it every spring (and from the questions and corrections sent in by readers in the comments below). The result is about 3 cups of sima from a single quart mason jar, and it’s easy to scale up if you’re hosting a crowd.
Notes from My Kitchen
What I love about this recipe (and what makes it different from almost every other ferment I make) is that the raisins do all the hard work for you. They drop nutrients for the yeast at the start, hold wild yeast on their skins, and float to the surface when it’s time to bottle.
They’re a biological turkey timer that tells you when the sima is ready to bottle. The five raisins floating up to the top of the jar after a day on the counter is one of the small everyday miracles of fermentation, and it’s the kind of thing my kids actually pay attention to when I tell them it’s about to happen.
Quick Look at the Recipe
- Makes: About 3 cups
- Active prep: 10 minutes
- Ferment time: 24 to 48 hours room temperature, plus 2 to 4 days refrigerator carbonation
- Lemon: 1 whole lemon, thinly sliced (or juice and zest of 1)
- Sweetener: Honey, sugar, or a blend
- Yeast source: A pinch of wine or bread yeast, or skip the commercial yeast and rely on the wild yeast on the raisin skins
- Bottles: Plastic soda bottles, or flip-top bottles made for carbonated drinks (not mason jars)
- Storage: In the fridge, in sealed bottles; drink within about a week
Ingredients for Sima
Five ingredients (one of which is technically optional, as you’ll see), all going into a single quart mason jar. The recipe scales up linearly if you want to make a half-gallon or gallon batch.
- Lemon (whole, organic if available): A whole lemon goes into the jar, sliced thin so the peel and pith both contribute. Most of the bright lemon flavor and aroma comes from the oils in the peel rather than the juice, so don’t be tempted to skip the slicing in favor of just adding juice. Organic or unwaxed is best because the peel goes in; if you can only find waxed lemons, scrub them well with hot soapy water first. Some traditional recipes use just the juice and zest of one lemon, which works too and produces a slightly less intense version.
- Honey (or sugar, or a mix): All honey, all sugar, or a blend; all three work and each gives a slightly different character. All honey gives the drink more of its old-school mead character and a rounded, floral finish. White or brown sugar gives a cleaner, simpler lemon soda flavor. The 1/2 cup amount in the recipe card is a starting point for a balanced, slightly sweet finish; if you prefer a drier sima, you can drop down to 1 or 2 tablespoons of sweetener and the recipe still works (the yeast just has less sugar to convert into bubbles).
- Raisins (unsulfured): The five raisins do triple duty in this recipe. They contribute a small amount of natural fruit flavor, they drop nutrients into the brew that feed the yeast, and they hold wild yeast on their skins that can carry the entire fermentation if you skip the commercial yeast. They also act as a built-in indicator: as the yeast gets going, the raisins pick up bubbles of CO2 and float to the surface, and that float tells you the counter ferment is done. Use unsulfured raisins if you can; sulfur dioxide kills wild yeast, so sulfured raisins lose the wild-yeast benefit (the other two purposes still work).
- Yeast (a pinch, optional with unsulfured raisins): A small pinch of yeast (literally a few grains, less than 1/16 teaspoon) is enough to inoculate the entire quart. Premier Blanc wine yeast is my preference if you have it, but standard active dry bread yeast works just fine for a ferment this short, and so does champagne yeast. Wild yeast from unsulfured raisins is also enough on its own; the commercial yeast just gets things going about a day faster. Nutritional yeast does not work; it’s dead yeast cells and won’t ferment.
- Water (filtered or unchlorinated): Enough water to fill the jar to within an inch of the top, which comes to about 2 1/2 to 3 cups once the lemon and honey are in. Plain tap water works if your municipal water isn’t heavily chlorinated; chlorine kills yeast and can stall the ferment. If you’re not sure, use filtered or boiled-then-cooled water, or leave a pitcher of tap water out uncovered overnight to let the chlorine off-gas. That works for chlorine, but not for chloramine, which many cities use instead; if yours does, use filtered water.
A note on the wild yeast on raisins: The five raisins in this recipe were originally there as nutrients and as the ferment indicator, but the wild yeast on their skins is enough to carry the entire fermentation on its own. If you’d like to make sima with no commercial yeast at all, use unsulfured raisins, and expect the ferment to take an extra day.
Honey also carries its own wild yeast, so a sima made with raw unfiltered honey and unsulfured raisins needs no commercial yeast at all; the yeast just comes from the ingredients you’ve already got in the jar.
How to Make Sima
Ten minutes of active work, then a 24-to-48-hour wait on the counter, then 2 to 4 days in the fridge to carbonate. Plan it so the carbonation finishes around when you want to drink it; for a Vappu celebration on May 1st, that means starting the batch around April 25th, or a day or two later in a warm kitchen.
Step 1. Combine the lemon, sweetener, and raisins. Slice 1 lemon thinly (or juice and zest 1 lemon, if you prefer) and add to a clean quart mason jar. Add 1/2 cup of honey or sugar (or a mix) and 5 unsulfured raisins. There’s no need to dissolve anything yet; the boiling water in the next step will take care of that.
Step 2. Pour near-boiling water over everything. Bring water to a near-boil (it doesn’t need to come to a hard boil) and pour it over the contents of the jar to fill to within 1 inch of the top. That’s about 2 1/2 to 3 cups of water. Stir gently with a clean wooden or plastic spoon until the honey or sugar is fully dissolved. The hot water both dissolves the sweetener and pulls the lemon oils out of the peel.
Step 3. Cool to between 90 and 100 degrees Fahrenheit. This is the step where most batches fail. Yeast starts to die off at around 120°F, and water can feel “warm, not hot” to your hand at temperatures close to that.
If this is your first batch, use an instant-read thermometer; if you don’t have one, leave the jar to cool until it’s barely warm to the touch (a finger held against the side of the jar should feel comfortably warm, not uncomfortably hot). This usually takes about 30 to 45 minutes at room temperature.
Step 4. Add the yeast. Sprinkle a pinch of yeast (a few grains, less than 1/16 teaspoon) onto the surface of the cooled liquid. Stir gently to incorporate. If you’re going wild-yeast-only, skip this step; the raisins are doing the work.
Step 5. Cover and ferment for 24 to 48 hours. Cover the jar with a silicone fermentation lid (which lets CO2 out but not air in), an airlock, or a coffee filter or clean cloth secured with a rubber band. A regular tight mason jar lid will also work, but you’ll need to burp it (briefly loosen and re-tighten) once or twice a day to release pressure.
Set the jar somewhere out of direct sunlight at normal room temperature (65 to 75°F is ideal). Check it morning and night; the ferment is done when all 5 raisins have floated to the surface, which usually takes 24 to 48 hours, sooner in a warm room.
Step 6. Strain and bottle. Once the raisins are floating, pour the sima through a fine mesh strainer into a clean bowl and discard the spent lemons and raisins. Use a brewing funnel to pour it into bottles made for carbonated drinks, either plastic soda bottles or heavy flip-top bottles, leaving about an inch of space at the top.
If you use glass, fill one small plastic soda bottle too, as a pressure tester. Don’t bottle sima in mason jars, since canning jars can’t safely hold carbonation pressure. You’ll have about 3 cups, and there’s no need to top it back up with water.
Step 7. Refrigerate to carbonate. Cap the bottles and put them straight into the fridge. The cold slows the yeast down but doesn’t stop it, so the gas it makes stays trapped in the bottle and carbonates the sima. That’s why the bottles stay sealed in the fridge, with no airlock.
Give the plastic bottle a squeeze once a day. When it’s firm and barely gives, the sima’s ready, usually in 2 to 4 days. Open the first bottle slowly over the sink, since a well carbonated sima can foam over. For the traditional Finnish signal, drop a couple of raisins into each bottle; when they rise to the top, the sima is fizzy.
Step 8. Drink within about a week. Sima is meant to be drunk fresh. The yeast keeps working in the fridge, so the sima gets drier, fizzier and a little more alcoholic the longer it sits, and the pressure keeps building. Once the tester bottle is firm, open each bottle briefly every day or two to let off extra pressure, then close it back up.
Recipe Tips
Use a thermometer the first time. A common reason a sima ferment won’t start is water that was still too hot when the yeast went in. Yeast starts to die off at around 120°F and is killed by 140°F, and water can feel “warm, not hot” to a hand at temperatures close to that. A cheap kitchen thermometer takes the guesswork out, and you’ll only need it for the first batch or two before you develop a feel for the right temperature.
Watch the raisins, not the clock. The 24-to-48-hour timing is a range, not a deadline. Warm rooms ferment fast; cool rooms ferment slow.
The raisins floating to the top is the actual indicator that the sima is ready to strain and bottle, and in a warm room that can happen in less than a day. If you’re seeing bubbles and the raisins are bobbing at the surface, it’s done; if it’s been 48 hours and the raisins are still on the bottom, give it another 12 hours or check that your water temperature didn’t kill the yeast.
Use bottles made for carbonation. The sealed bottle is what traps the bubbles, and it’s also what can break if the pressure climbs too high. Plastic soda bottles are the safest choice, since you can feel the pressure building and they bulge before they fail. Heavy flip-top bottles made for beer or soda work too, but you can’t feel the pressure in glass, so fill one plastic bottle alongside them as a tester. Keep mason jars for the open ferment on the counter.
White film on top is normal and harmless. If you see a thin white film forming on the surface during the room-temperature ferment, that’s kahm yeast, a wild yeast that grows on the surface of many home ferments. It’s not mold and it won’t make you sick.
Skim it off and carry on; it doesn’t affect the safety of the finished sima. Mold is fuzzy and colored (green, blue, black, or pink); kahm is flat and white. If what’s on top of your sima is fuzzy or colored, throw the whole batch out.
The wild yeast on raisins is enough. If you’ve ever wanted to brew without a packet of commercial yeast in the cupboard, sima is the place to start. Five unsulfured raisins carry enough live yeast on their skins to inoculate the whole quart, and the ferment goes the same way, just a day or so slower. It’s a gentle introduction to wild fermentation, and it works reliably with grocery-store unsulfured raisins; you don’t need to source anything special.
Variations
The base sima technique adapts to a wide range of fruits and ferment styles. A few that work:
- Less sweetener: Drop the honey or sugar to 1 to 2 tablespoons for a much drier, more tart sima. The yeast quickly converts the small amount of sugar to carbonation and the result is closer to a sparkling lemonade than a sweet soda. Start light; you can always stir more honey into a finished bottle, but you can’t take it out once it’s in.
- Other fruits, same method: The sima technique works well with strawberries, rhubarb, grapefruit and orange. If you’re substituting for the lemon entirely, add a tablespoon of lemon juice to the jar to keep the acidity high enough; otherwise the ferment can go off-balance. Finnish readers also make it with fireweed flowers or blackcurrant leaves, and fireweed turns it pink.
- Currants or cranberries instead of raisins: Any dried fruit with natural surface yeast works. Dried unsulfured currants, cranberries, and even chopped dried apricots all carry enough wild yeast to do the job. Use the same number (5 pieces, give or take) as the recipe calls for raisins.
- Sourdough starter or ginger bug: A teaspoon of active sourdough starter or a tablespoon of ginger bug works in place of commercial yeast and gives the sima a slightly more complex, tangy character.
- Longer ferment for higher alcohol: Let the room-temperature ferment go for a full 5 to 7 days instead of 24 to 48 hours, then strain and bottle. The result is closer to a short mead, dry rather than sweet and noticeably more alcoholic, so it’s no longer a drink for kids. A hydrometer lets you measure how much alcohol is in the finished drink. Go longer still and you’re making herbal mead.
Serving and Cocktails
Sima is traditionally served chilled, straight from the bottle, alongside tippaleipä (Finnish funnel cakes) on Vappu.
Pour ice-cold sima into tall glasses straight from the bottle, no ice (the sima dilutes too much with ice). Serve alongside funnel cakes, donuts, or another fried sweet pastry. The contrast between the bright effervescent drink and the rich fried dough is the entire point.
For more naturally fermented drinks in the same family, see my smreka (Balkan juniper soda) and tepache (Mexican pineapple soda), plus traditional bread kvass. To round out a Vappu spread, try my Finnish pancakes (Ålandspannkaka), Finnish teaspoon cookies, and Finnish salmon soup.
“Hello from Finland! This year I did my sima from sourdough starter and it was even better than the original in my opinion. We make it from all kinds of things, for example rhubarb, fireweed (the color from the precious ones is a beautiful pink) and also from blackcurrant leaves. Have a nice summer!”
Sima FAQs
These are the questions that come up most in the comments, most of them about bottling and carbonation.
Sima is very low in alcohol, closer to a homemade lemon soda than a mead, and in Finland it’s traditionally shared with kids at Vappu. The short ferment doesn’t give the yeast much time to make alcohol. A longer ferment, or bottles kept well past a week, raise the alcohol, so stick to the short ferment if kids will be drinking it.
Usually the water was too hot when the yeast went in. Yeast starts to die off at around 120°F, and water can feel “warm, not hot” to your hand at temperatures close to that. To rescue the batch, check that the jar is at room temperature and add another small pinch of yeast; it should pick up within about 12 hours. A cold room (below 65°F) can stall the ferment too, so move the jar somewhere warmer and give it another day.
No. The airlock, lid or cloth is only for the open ferment on the counter. Once you strain the sima, it goes into sealed bottles in the fridge, and the sealed bottle is what holds the bubbles in. Use plastic soda bottles or flip-top bottles made for carbonated drinks, not mason jars, and open them briefly every day or two once they’re fizzy.
No. A batch makes about 3 cups once the lemon and raisins are strained out, so ending up with less than a full quart is normal. Adding water now would just dilute the flavor and the sugar the yeast needs for carbonation.
That’s kahm yeast, a harmless wild yeast that often forms on the surface of home ferments. It’s flat and white, a little like a thin skin, and you can skim it off and carry on. Mold is different: it’s fuzzy and colored (green, blue, black, or pink), and if you see it, throw the whole batch out and start over.
More Drinks
More homemade drinks to try, from fermented sodas to cordials.
If you tried this Finnish Fermented Lemonade (Sima) recipe, or any other recipe on Adamant Kitchen, leave a ⭐ star rating and let me know what you think in the 📝 comments below!
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Sima ~ Finnish Fermented Lemonade
Equipment
- Funnel
Ingredients
- 1/2 cup honey, or brown sugar
- 1 large lemon, thinly sliced, or juice and grated zest
- 5 whole raisins, unsulfured
- 1 pinch yeast, ideally wine yeast, but bread yeast will do
- 2 1/2 cups water, near-boiling, enough to fill the jar
Instructions
- Add the lemon, sweetener, and raisins to a clean quart mason jar.
- Pour near-boiling water over the contents to fill within 1 inch of the top. Stir gently to dissolve the sweetener.
- Let it cool to between 90 and 100°F. Use a thermometer for the first batch, since the water can feel warm to the hand at temperatures hot enough to harm the yeast.
- Add a pinch of yeast (or skip it if you’re relying on the wild yeast on unsulfured raisins) and stir it in.
- Cover with a silicone fermentation lid, an airlock, or a coffee filter or clean cloth secured with a rubber band. Ferment at room temperature (65 to 75°F) for 24 to 48 hours, until all 5 raisins have floated to the surface.
- Strain through a fine mesh strainer and pour into plastic soda bottles or flip-top bottles made for carbonated drinks, leaving about an inch of headspace. Don’t use mason jars for this step. If you use glass, fill one small plastic bottle too, as a tester.
- Cap the bottles and refrigerate. Squeeze the plastic bottle once a day; when it’s firm, usually in 2 to 4 days, the sima is carbonated.
- Drink within about a week. Once the bottles are carbonated, open each one briefly every day or two to let off extra pressure, opening slowly over the sink since it can foam.
Notes
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
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If I have my own raw honey from our bees and lemons from our tree and raisans/grapes from our vine, not sprayed, can I ferment this and not use storebought yeast?
Yes, that’ll work just fine. Honestly, the yeast isn’t strictly required. The honey has yeast in it, as do the raisins on the skins, even when working with commercial honey and fruit. The yeast just gets it going faster. You may need to wait an extra day when working with wild yeast, but it’ll work just fine without it. Enjoy!
Real tasty recipe. We made a second time using ripe mayapples and it turned out great as well. Thanks for posting!
Sounds like it would be great to make a Tom Collins with too