What Happens if You Ferment Filmjölk for 4 Weeks? (I Tried It)

The Four-Week Culture: What Happens When Filmjölk Lives Too Long?

Fermentation is a dance with living organisms, and usually, we step in right when the rhythm is perfect. With filmjölk, that sweet spot is normally around 24 hours on the counter. But what happens if you just let it keep going?  Driven by pure curiosity, I left a batch of traditional Swedish filmjölk fermenting for an entire month, tasting it and documenting the changes every seven days. 

From subtle changes in texture to a dramatic transformation in flavour and appearance, here is what happens when you push this countertop culture to its absolute limits, week by fascinating week.

Whey separation after two weeks of room-temperature fermentation

Safety First

Wild fermentation is a beautiful process, but safety should always come first. 

This post documents my personal experiment to observe microbial behavior over an extended period.  Standard filmjölk is fermented for 24-48 hours. 

This documents my personal experiment rather than a recommended method of preparing filmjölk.  If mould develops, unusual colours appear, or the culture smells obviously spoiled, discard it immediately.  Never consume dairy that looks or smells unsafe. 

Disclosure: Some links below are Amazon affiliate links.  If you make a purchase through them, I may earn a small commission at no extra cost to you.  I only recommend products that I use myself or would happily use in my own kitchen.

The Baseline: What is Filmjölk Supposed to Be?

Before diving into a month of microbial madness, we need a baseline.  What should filmjölk look, smell, and taste like.

In its standard form, filmjölk is a traditional Swedish fermented milk product.  Unlike regular yoghurt, which requires high temperatures to culture, filmjölk relies on several mesophilic bacteria.  These microbes thrive at room temperatures, allowing the milk to ferment in a jar on my kitchen counter. 

Under normal circumstances, the fermentation process is short and sweet, generally lasting anywhere from 18 to 48 hours.  

I culture mine in simple glass jars.  I strongly prefer wide-mouth fermentation jars because they're easier to fill, clean and scoop from than recycled jars with narrow necks.

For Australian readers I recommend these wide-mouth fermentation jars.

For international readers these are the wide-mouth fermentation jars I recommend.

A standard batch of homemade filmjölk should hit these notes:

Texture: Thick, smooth, and distinctly pourable.  It should comfortably coat the back of a spoon, sitting right in the goldilocks zone between regular milk and thick yoghurt.  I prefer mine thicker, so generally allow it to ferment a little longer. 

Flavour: Mildly tangy and acidic with a unique, subtle buttery undertone.  This buttery aroma comes from diacetyl, a natural byproduct of the mesophilic fermentation process.  My kids say it is like drinkable sour cream. 

Appearance: Uniformly white, glossy, and completely cohesive, with little to no separation of liquid whey.  Photographing filmjölk isn't easy.  A fresh batch looks remarkably similar to ordinary milk in a photograph.

This is the comforting, delicious baseline we are aiming for.  

But what happens when you leave those living bacteria in charge for 600 hours longer than they expect?  Let’s find out.

Summary of filmjölk over-fermentation experiment

Fermentation Time	Texture	Flavour	My Verdict
24–48 hours	Smooth, thick and pourable	Mildly tangy with buttery notes	Excellent
7 days	Thicker with slight whey separation	Noticeably sharper but still pleasant	Still Very Good
14 days	Firm curds with lots of whey	Quite acidic	Edible, but not my favourite
21 days	Odd texture	Unusual aroma and flavour	I stopped serving it to my kids
28 days	Very strange appearance and texture	Unpleasant	I wouldn't eat it again - possibly unsafe

Week 1: The Subtle Shift in Tartness

After seven days the filmjölk was noticeably thicker than normal and had begun to separate slightly, with a small amount of whey collecting around the edges.  The flavour had become noticeably more acidic, but it still retained the buttery notes that make filmjölk distinctive.

At this stage I was still happy to eat it, and my kids tried some as well.  None of us noticed any ill effects, although the stronger flavour was starting to move away from what I normally enjoy.

One unexpected lesson from this experiment had nothing to do with fermentation.  I usually culture filmjölk in wide-mouth jars, but this time I used a recycled narrow-necked jar.  Every time I scooped some out I made a mess, which reminded me why wide-mouth fermentation jars are so much more practical.  

This experiment reminded me why I normally use wide-mouth fermentation jars.  They're much easier to clean and make it far easier to remove thick filmjölk without making a mess.

For Australian readers I recommend these wide-mouth fermentation jars.

For international readers these are the wide-mouth fermentation jars I recommend.

Filmjölk getting thicker after 7 day ferment

Week 2: Separation and the Rise of Whey

By the second week the changes became much more obvious.  A significant layer of whey had separated from the thick curds.  I poured off most of the separated whey before tasting the thicker curd beneath.

This separation is fairly normal in cultured dairy.  I also see similar whey separation when making farmer's kefir cheese or tvorog.

The remaining curd had become quite firm.  I could slice pieces away with a spoon and they briefly held their shape before slowly collapsing.  The flavour was still recognisably filmjölk, although much sharper and less pleasant than a normal 24-hour batch.

I still considered it edible at this stage, even if it was no longer as enjoyable.  Visually it started looking a little strange, but there were no obvious signs of spoilage such as mould or discolouration.

Filmjölk after 14 day fermentation is still good

Week 3: Crossing Into Unknown Territory

After three weeks the filmjölk had changed enough that I became cautious.  The texture had become unusual and the aroma was no longer the familiar buttery smell of fresh filmjölk.  It wasn't the smell of spoiled milk, but it also wasn't something I found overly appealing.

I tasted only a small amount.  I didn't become ill afterwards, but this was the first point in the experiment where I even questioned whether continuing to taste it was a sensible idea.  Because of that uncertainty I didn't let my children try any.

Although I can't say exactly what microbial changes were taking place, it seemed likely that the balance of microorganisms had shifted considerably, although I can't say exactly what was happening without laboratory testing. 

Filmjölk after 21 days of fermentation

Week 4: The Ultimate 30-Day Result

After four weeks the filmjölk no longer resembled something I wanted to eat.  The texture had become strange, the smell was unpleasant, and although I tasted a tiny amount out of curiosity, I had no desire to eat any more.

I didn't experience any illness after that small taste, but I certainly wouldn't recommend intentionally fermenting filmjölk for this long.  Even if it happened to be microbiologically safe, the flavour and texture had deteriorated to the point where there was little reason to continue.

One surprise remained.  Before discarding it, curiosity got the better of me.  I used a spoonful of the four-week-old filmjölk as a starter culture for fresh milk.  To my surprise, it fermented into what looked, smelled, and tasted like perfectly normal filmjölk after 24 hours.  I expected the culture to fail completely or need several generations to recover, but that wasn't what happened.  This was the biggest surprise of the entire experiment.

I simply added a spoonful to fresh milk at room temperature and left it to ferment as normal.  I don't usually measure the temperature exactly, but if your house varies a lot, a thermometer strip can be helpful.

For Australian readers, I recommend these thermometer strips.  They are inexpensive, adhesive, simple to use, and surprisingly accurate.

For readers from other countries, these are the thermometer strips I recommend.

Side note after 4 week fermentation 

One unexpected casualty of this experiment was the jar itself.  The narrow neck made cleaning almost impossible after a month of thick fermented milk, so I eventually gave up and recycled it.  It's another reminder of why I almost always use wide-mouth fermentation jars. 

After throwing away this jar, I was reminded why I almost always use wide-mouth jars for fermentation.  They cost a little more than recycled jars, but after years of making kefir, filmjölk and kombucha I think they're well worth it.

For Australian readers I recommend these wide-mouth fermentation jars.

For US and other international readers these are the wide-mouth fermentation jars I recommend.

This Is Why I Typically Use Wide Mouth Jars

The Verdict: Is 4-Week Filmjölk Edible?

If the question is "Can filmjölk ferment for four weeks?", then the answer is clearly yes.

If the question is "Should you eat four-week-old filmjölk?", my answer is no.

I didn't become ill after tasting small amounts throughout the experiment, but by the third week I was no longer confident enough to recommend eating it, and by the fourth week it simply wasn't enjoyable anyway.  

Frequently Asked Questions

Can you ferment filmjölk for a week?

Yes.  Mine became noticeably thicker and more acidic but was still pleasant to eat.

Can filmjölk ferment for two weeks?

It can, although mine separated into curds and whey and the flavour became sharper.

Can filmjölk ferment for a month?

Mine did, but by that stage the texture, smell, and flavour had deteriorated so much that I wouldn't recommend eating it.  I probably could have fermented it longer, but I didn't enjoy eating it after a month and decided that even longer would likely be less pleasant.

Can over-fermented filmjölk still be used as a starter?

Surprisingly, yes.  In my experiment, a four-week-old culture still successfully fermented fresh milk into a normal batch.

Why did my filmjölk separate into curds and whey?

Whey separation is a normal part of extended fermentation.  As the culture becomes more acidic, the milk proteins tighten and release liquid whey.  Small amounts of separation are perfectly normal, although excessive separation usually means the filmjölk has fermented longer than intended.

Does filmjölk keep fermenting in the refrigerator?

Yes, although much more slowly.  Refrigeration greatly slows the bacteria, but it doesn't stop fermentation completely.  Filmjölk often becomes thicker and tangier the longer it is left in the fridge. 

Where to get filmjölk starter

Want to try making your own filmjölk at home?  I occasionally have live filmjölk cultures available, along with kefir grains, and other fermentation starters.  You can check my current availability here.

If you're outside Australia or I don't have cultures available, you can also buy a freeze-dried filmjölk starter online.  For readers in the United States, this is the filmjölk starter I'd choose because it's inexpensive, easy to use, and produces authentic filmjölk.

Unfortunately, Amazon Australia rarely stocks genuine filmjölk starter cultures.  You can sometimes find Nordic style mesophilic starter cultures instead. While they don't produce traditional filmjölk, they can make a similar cultured milk and are a good introduction to room-temperature dairy fermentation.  

Related Fermentation Articles

• How to Make Filmjölk at Home

• Filmjölk vs Kefir

• Making Milk Kefir at Home

• Farmer's Kefir Cheese Recipe

• Two Ingredient Buckwheat Sourdough with Kefir

• Two Ingredient Buckwheat Sourdough with Kombucha

Final Thoughts: The Resiliency of the Culture

Four weeks, one jar, and a massive spectrum of changes.  

A month of continuous fermentation revealed just how resilient a filmjölk culture can be.  The bacteria continued acidifying the milk long after I would normally stop the process, resulting in dramatic changes in flavour, texture, and appearance.

For me, the sweet spot remains somewhere around 24 to 48 hours.  Beyond that, the extra acidity adds little and eventually produces a product that simply isn't enjoyable.

The biggest surprise came at the end of the experiment.  Even after four weeks, a spoonful of the old culture successfully fermented a fresh batch of milk into perfectly normal filmjölk.  The ageing batch had become unpleasant to eat, but the starter culture itself was still very much alive.

Sometimes experiments don't produce a better recipe, they simply teach us where the limits are. 

Can Elkhorn Ferns Survive Frost? My 8-Month Cold Climate Update

Almost a Year Later

Elkhorn ferns (Platycerium bifurcatum) are often recommended for warmer climates where they generally thrive.  I wanted to see if they could adapt to my colder garden conditions.  Around eight months ago I mounted several young elkhorn ferns around my garden to see whether they could survive and grow in my cold climate.  Some arrived in excellent condition, while others were already struggling.

I was not expecting to receive these elkhorn ferns, so was rather unprepared when they arrived.  I used string to mount them on scraps of timber, and used compressed cocopeat as the backing.  

If I were mounting these again, I'd use sphagnum moss and attactive staghorn mounting boards (they come in heaps of different styles, so I would pick my favourite looking ones).  I've linked the products I recommend near the end of this article for both Australian and US readers.

I am not an expert when it comes to elkhorn ferns and staghorn ferns, but I am loving growing them.  I wrote a previous post Growing Elkhorn Ferns in cold climate when my ferns were newly mounted.  I have grown Elkhorns when I lived in the subtropics, and also experimented with growing other Platycerium ferns from spores.   

After around seven or eight months, the results with my elkhorn ferns have been mixed.  A few have grown well, some have barely changed, and one didn't survive at all.  I am in a cold climate which is not ideal for growing these ferns, and it is currently mid winter so they are suffering a little from the cold, but that is life in my garden.

I thought it would be useful to show how each fern has performed so far, what I think helped the successful ones, and what I would do differently if I were starting again.

Quick Overview

Fern	Starting Condition	8 Month Result	My Thoughts
Fern #1	Two plants mounted together	One survived and grew	Successful despite pest damage
Fern #2	Poorly attached mount	Growing well	Surprisingly resilient
Fern #3	Already struggling	Died	Too damaged to recover
Larger fern	Temporary mount	Producing new fronds	Needs proper mounting

Elkhorn Fern #1: Survived Caterpillar Damage

The first elkhorn is surviving and somewhat growing.  This was two plants together, the one on the left died and the one on the right is growing well.  

Not long after I mounted this I noticed frass, and a caterpillar was in the plant on the left.  It ate the growing point and killed that plant.  Normally I would submerge a plant like this to drown caterpillars, but as I mounted on a plank of wood this was not an option.  I used fly spray, which did the job.  

Below you can see comparison photos.

This Elkhorn Fern Survived

This is what it looked like originally

Elkhorn Fern #2: The Surprisingly Successful One

I didn't attach the second elkhorn fern very securely, yet it has turned out to be one of the strongest growers.  The shield fronds have browned off somewhat, which is normal for elkhorns in my climate at this time of year.  It has grown several new foliar fronds that look healthy, and you probably can't see in the photo it is beginning to grow a new shield frond.

This fern has convinced me that elkhorn ferns are more forgiving than their reputation suggests, provided the growing point remains healthy.

Below you will see comparison photos from when I mounted it until now.

This Elkhorn Fern Grew Well

This is what it looked like originally

One Elkhorn Fern Died

Not Every Elkhorn Fern Survived.

This was looking poorly when I mounted it.  One day we had a storm with big winds, and this little fern was snatched away.  I searched for it, but it took me a few days before I found it.  When I found it, the fern looked dry and dead.  I mounted it again just in case, but it was dead and slowly degraded until it completely fell apart.

Below is the photo when I mounted it.  

This one was struggling when I received it

An Elkhorn Fern That Is Still Hanging On

The lowest fern I am not sure about.  When I first mounted it I was confused by its shape and looking back, I think I accidentally mounted it sideways.  This isn't great for them.  

This one elkhorn is still alive, and has grown new fronds.  I am not sure if it will survive, but I have hopes if it gets through winter it might pick up and grow well in spring.  

This fern isn't looking great, but could pick up

This is what it looked like when I mounted it

My Largest Elkhorn Fern Is Growing

I also have one large elkhorn fern.  I temporarily mounted it on a piece of timber using string, and put it in my unheated greenhouse out of the wind.  This one dropped some if its fronds.  Since then it started growing new shield fronds, and new foliar fronds.

This needs to be mounted properly, the string I used is too flimsy and is only doing the job temporarily because it is out of the wind.  

I put this in my greenhouse, and largely forgot about it.  I water it from time to time when it gets dry, and have every intention of mounting it properly.  Given it is winter, I don't want it to put on a lot of new growth until the weather warms.  In spring I plan to mount it better, and may keep it in the greenhouse as it seems to be doing well here.

My largest elkhorn fern is surviving

Elkhorn growing new shield fronds

Large elkhorn fern when I first got it

Frequently Asked Questions

What is the difference between elkhorn and staghorn ferns?

Elkhorn and staghorn ferns are closely related, but they are different species and the common names can sometimes be confusing and often differs between countries and regions.  In Australia, elkhorn ferns (Platycerium bifurcatum) are usually smaller plants that spread by producing pups, eventually forming large clumps.

Staghorn ferns (Platycerium superbum) grow much larger, usually as a single impressive plant, and they are not known for producing pups as readily as elkhorn ferns.

Can elkhorn ferns survive cold climates?

Yes, provided they do not experience many heavy frosts.  Mine have survived down to -5C so far under cover, and I expect temperatures to drop to -10C before winter is over. 

Do elkhorn ferns lose fronds in winter?

Sometimes mine lose foliar fronds over winter, and often the shield fronds brown off.  This is normal and they should resume growing once spring comes.

Can elkhorn ferns grow on timber?

Elkhorn ferns can be mounted on live trees, or timber, or plastic, and some people mount them on stones or tree fern trunks.  

Can Elkhorn Ferns Survive Frost?

Elkhorn ferns can sometimes survive a light frost, especially larger established plants, but they are not frost tolerant.  Sustained heavy frosts, like those we experience in my garden, would likely damage or kill them.

Mine have survived temperatures below freezing so far because they are protected from frost, but I would not expect them to tolerate repeated hard frosts without protection.  Low temperature is less problematic, frost is the issue.

Tips for Growing Elkhorn Ferns in Cold Climates

• Protect from heavy frost
• Keep them sheltered from cold winds
• Mount them where they can drain freely
• Reduce watering during cold weather

What I Would Do Differently Next Time

Looking back, my biggest mistakes were using string instead of proper garden wire, and mounting them quickly on a plank of wood I had in the garage because I wasn't prepared.  If I received another batch of young elkhorn ferns, I would have proper mounting boards, sphagnum moss, and wire ready beforehand. 

Products I Wish I Had Used

This post contains affiliate links. If you buy through these links, I may earn a small commission at no extra cost to you. I only recommend products that I use myself or would happily use.

If you're planning to mount your own elkhorn ferns, these are the materials I wish I had used for mine.  Had I more time and warning that I was about to receive these incredible plants, I would have bought:

For Australian readers:

Many people use sphagnum moss for mounting elkhorns.  I used coco peat because I had some in the garage at the time.  They both work for elkhorn ferns, but sphagnum moss is a better option. 

• Compressed coco peat blocks for the backing 
• Sphagnum moss for the backing 
• Staghorn mounting boards better than scraps of timber
• Plastic coated garden wire to secure the fern - far better than the string I used!
• Fish emulsion fertiliser to encourage healthy growth.

Products for US readers:

• Compressed coco peat blocks for the backing 
• Sphagnum moss for the backing 
• Staghorn mounting boards better than scraps of timber
• Plastic coated garden wire to secure the fern - far better than the string I used!
• Fish emulsion fertiliser to encourage healthy growth.

I have not heavily fertilised these yet because they are still establishing and it is winter so I do not want much growth until spring and the weather is warmer.  I plan to fertilise over the warmer months, fish emulsion is commonly used by fern growers once plants are actively growing. 

Final Thoughts

While not every fern survived, I have been pleasantly surprised by how well most of these elkhorn ferns have adapted to my colder climate.  The healthiest plants are continuing to produce new shield and foliar fronds despite winter conditions, giving me confidence that they will perform even better once spring arrives.

I'll continue updating these ferns as they mature, particularly after another winter, to see whether they become fully established outdoors.

Related Articles

If you enjoyed following this elkhorn fern experiment, you may also enjoy some of my other plant and growing experiments, where I test unusual plants, propagation methods, and growing techniques in my own garden. 

• Growing Elkhorn Ferns in Cold Climate
• Growing Staghorn Ferns From Spores - 6 month update
• African Violet Wicking Pots Experiment
• Trampoline Fern Update
• Maidenhair Fern Variety Comparison

Blue vs Pink Rosemary: Which One Is Better for Your Garden?

I have grown several rosemary plants over the years, but two have really stood out to me.  Both are unnamed varieties that I originally planted simply as rosemary, yet after growing them side by side for several years I noticed some interesting differences.

The blue-flowering rosemary has become a large, vigorous shrub that provides shade, attracts pollinators, and produces more rosemary than I can use.  The pink-flowering rosemary stays much smaller and more compact, making it a better choice where space is limited.

This isn't a comparison of named commercial cultivars. Instead, it's a practical comparison based on growing these two rosemary plants side by side in my own garden over the past few years.

Which rosemary is better - Quick Answer

If you're choosing between the two, I'd grow the blue rosemary for production and the pink rosemary where space or appearance matters more.  Both taste almost identical.

This post contains affiliate links.  If you purchase something through these links, I may earn a small commission at no extra cost to you.  I only recommend products I personally use or believe would be useful.

Comparison of blue and pink rosemary varieties

The Large Blue Flowered Rosemary

My blue flowered rosemary is the larger and more vigorous of the two plants.  Blue rosemary is commonly grown in gardens, there are plenty of varieties to choose from.

Mine has now grown to over 6 feet (~1.8 metres) tall and has become one of the largest shrubs in my edible garden.  This plant is a permanent feature beside my chicken run.  I planted it on the western side where it provides some afternoon shade and protection.

One of my favourite things about this rosemary is how much it flowers.  It produces masses of blue flowers.  One thing I notice every time it flowers is how quickly bees and other beneficial insects find it.  On warm sunny days the flowers are often covered with pollinators.

If you are growing rosemary as a large shrub, a good pair of pruning shears makes maintenance much easier, it also makes harvest simple.  

I use these pruning shears, I have smaller hands and find they fit me better than many of the larger styles I have tried.  For me, they are much more comfortable to use when trimming and harvesting herbs.  As this rosemary grows thick woody stems, pruning shears make harvest simple. 

The leaves of my blue rosemary have a strong rosemary aroma and flavour.  Compared with my pink flowering rosemary, I think the aroma is slightly stronger, although if I wasn't growing them side by side I'm not sure I'd notice the difference.

The Pretty Pink Flowered Rosemary

I wrote previously about my pink flowered rosemary, which has a very different growth habit.  This is a rarer rosemary variety. 

Rather than becoming a huge shrub, this plant has stayed shorter and more compact.  It is less vigorous, but the flowers are beautiful and make it a very attractive garden plant.

I think this rosemary would suit smaller gardens, balconies, or growing in pots where a large spreading shrub would become difficult to manage.

Pink Rosemary vs Blue Rosemary

Can You Eat Pink Rosemary?

Yes.  My pink flowering rosemary tastes almost identical to the blue flowering plant.  Although I think the blue variety may have a slightly stronger aroma, the difference is subtle.  Both are excellent culinary herbs, and I use them interchangeably in cooking.

Blue vs Pink Rosemary Comparison

Feature	Blue Flowered Rosemary	Pink Flowered Rosemary
Growth habit	Large, vigorous shrub	Smaller and more compact
Size	Over 6 feet tall	Much shorter
Flowers	Lots of blue flowers	Pretty pink flowers
Pollinators	Excellent, many flowers	Good, but fewer flowers
Best use	Large gardens, hedges, shade planting	Pots and smaller spaces
Flavour	Very similar, possibly slightly stronger	Very similar

If you're growing rosemary in containers, I prefer reasonably large terracotta-style pots because rosemary dislikes sitting in wet soil.  

Rosemary comparison

What About Prostrate Rosemary?

This comparison does not include prostrate rosemary, which is another common type of rosemary with a completely different growth habit.

Prostrate rosemary grows along the ground rather than forming an upright shrub, making it useful for rockeries, retaining walls, and ground cover.  

I grow this too, but it mostly gets lost among my other plants and the upright versions are the ones we mostly use for cooking.  For spilling over retaining walls, my go to plant is Jekka's thyme. 

For this comparison I am only looking at upright rosemary plants.

Do Bees Prefer Blue or Pink Rosemary?

I tend to see honey bees on all my rosemary plants.  The blue variety has more flowers, so tends to have more bees.  As the pink rosemary grows larger, and flowers more, I am expecting it to attract similar amounts of pollinators. 

Rosemary attracts many beneficial pollinators

Which Rosemary Would I Grow?

After growing both, I have no plans to remove either one.  They fill different roles in my garden, and that's exactly why I like having both.   

The large blue flowered rosemary is incredibly useful.  It provides height, shade, flowers for pollinators, and plenty of rosemary for cooking.  I grow this on the western side of my chicken run to provide afternoon shade. 

The pink flowered rosemary is less productive as a large shrub, but it earns its place because it is attractive and easier to fit into a smaller space.  This variety still produces enough rosemary for cooking.  I am also growing this near the chicken run for shade, but have it in a place where I want something shorter.

If I only had room for one rosemary plant, I would choose based on the space available rather than flavour.

For a large garden, the vigorous blue flowering type wins.  For a pot or small garden or if I wanted something more unique, the prettier pink flowering rosemary is probably the better choice.

I grow both of these rosemary plants in my own garden, as well as an unnamed prostrate rosemary.  I currently sell the vigorous blue flowered rosemary, and plan to offer the pink flowered type in the future as I build up stock.  My current plants for sale can be found on my plant sale page.

I grow rosemary near my chicken run

Related Posts

• Pink Flowered Rosemary for the Edible Garden
• Thyme Variety Comparison - which is the best edible thyme variety
• Other Perennial Herbs I Grow - catalogue of herbs and perennial vegetables I grow
• Chicken Run Salad Bar - fresh greens for chickens - how I grow fresh greens for my hens
• Keeping Chickens Laying Through Winter: My Results With Artificial Light - easy way to increase eggs through winter

Kefir vs Filmjölk: Which Cultured Milk Is Easier and Better for Beginners?

Kefir vs Filmjölk: Which Cultured Milk Is Better?

If you're trying to decide between kefir and filmjölk, both are excellent cultured milk products.  After making kefir for several years and filmjölk for several months, I think filmjölk is easier for complete beginners, while kefir offers a little more flexibility once you're comfortable maintaining the grains.

When people first discover fermented milk, they usually hear about kefir.  It's one of the best known cultured dairy products and has a reputation for being incredibly healthy.  Kefir is surprisingly easy to make.

Filmjölk is much less well known outside Scandinavia, despite being one of the easiest cultured dairy products to make at home.  If you can believe this, its even easier to make than milk kefir.  If you haven't tried filmjölk before, I wrote a separate guide showing how I make it at home: How to Make Filmjölk at Home (And Why My Kids Prefer It to Kefir) .

After making milk kefir for several years and filmjölk for several months, I've found they each have strengths.  I still keep both cultures alive because I use them for different purposes.

If you're trying to decide whether to start with kefir or filmjölk, here's what I've learned.

This article contains affiliate links. If you purchase through these links, I may earn a small commission at no additional cost to you.

My home made filmjölk and milk kefir 

What Is The Difference Between Kefir And Filmjölk?

Although both are fermented milk products, they are made quite differently.

Milk kefir is produced using living kefir 'grains'.  These aren't true grains, and pose no danger to anyone with grain allergies.  These grains contain a mixture of bacteria and yeasts that work together to ferment milk.

Filmjölk does not use grains.  Instead, you save a small amount of finished filmjölk and use it to start the next batch.

If you’re deciding which one to start with, the biggest factor is whether you want to maintain kefir grains or prefer a simpler starter-based culture.  From a practical point of view, filmjölk is probably the simpler of the two.

My milk kefir grains 

Quick Comparison: Kefir vs Filmjölk

Feature	Milk Kefir	Filmjölk
Culture type	Kefir grains	Starter culture
Flavour	Tangy, slightly yeasty	Mild and buttery
Texture	Drinkable	Thick and spoonable
Maintenance	Needs grains separated after each batch	Save some finished culture for the next batch
Difficulty	Very easy	Very easy

Filmjölk is thick and spoonable 

Taste: Kefir vs Filmjölk

This is probably the biggest difference between milk kefir vs filmjölk.

Milk kefir has a distinctive tangy flavour that some people love immediately, while others take a little time to appreciate.  Depending on time of year, it can also develop a slight yeasty flavour and sometimes a little natural carbonation.

Filmjölk is much milder.

It has a buttery flavour with gentle acidity that reminds many people of yoghurt, although the texture is smoother and I find it less sour than Greek yogurt.

When I first made filmjölk, I was surprised how easy it was to enjoy straight away.

Which One Do My Kids Prefer?

This surprised me.

I expected everyone to prefer kefir because my kids have grown up drinking it and have always enjoyed it.  

Instead, my children immediately preferred filmjölk.

The milder flavour makes it much easier for people who aren't used to fermented foods, and apparently it's also nicer for kids who grew up drinking kefir.

That doesn't mean kefir is worse.  My kids still like it and drink it most days, they just prefer filmjölk.  Milk kefir just has a stronger flavour.

Making Filmjölk at home - saving some starter for the next batch 

Which One Is Easier To Make?

Both are easy.

Kefir requires one extra step.

After each batch you need to strain out the kefir grains before starting another batch.  I use a plastic mesh strainer because it makes separating the grains quick and simple.

Filmjölk skips this step completely.

To make more filmjölk you simply keep a little from the previous batch and add fresh milk.

If someone told me they had never fermented anything before, I would probably suggest starting with filmjölk because there is less to think about.

Straining my milk kefir grains 

Equipment I Use

I often make both cultures in recycled jars, but they are such a pain to clean.  It's far better to use ordinary glass preserving jars.  They are inexpensive, easy to clean, and the wide opening makes stirring and cleaning easier.

I also keep thermometer strips nearby, especially during winter when my house is cooler and fermentation slows down.  It's interesting how useful these things are. 

Once fermented, I store the finished milk in glass storage jars in the refrigerator.  I keep a lid on while in the fridge, otherwise there is a risk that they will absorb odours and off tastes from the fridge.

I don't use yogurt makers, or incubators, or heating mats to make kefir or filmjölk.  They aren't needed.  My house gets cold over winter, and my ferments always do just fine (althoughsometimestheymight need an extra day before they are ready).

Which One Is Healthier?

This is a common question.

Both contain live cultures, but they are not the same cultures.

Kefir is reported to contain a wider variety of beneficial bacteria and beneficial yeasts than filmjölk, although the exact number depends on the individual culture. 

Filmjölk contains its own traditional cultures and is also a live fermented food.

Rather than saying one is better, I think they are simply different.

I happily consume both.  I personally think of kefir as food and as home remedy medicine, while I only tend to think of filmjölk as food.  

Should You Choose Kefir or Filmjölk?

If you're still undecided, here's a quick summary based on my own experience making both at home.

If you want...	My recommendation
A mild flavour that's easy to enjoy	Filmjölk
A stronger, tangier cultured milk	Kefir
The easiest culture for complete beginners	Filmjölk
A culture with beneficial bacteria and yeasts	Kefir
A thick, spoonable breakfast	Filmjölk
A drinkable fermented milk	Kefir and Filmjölk
The least day-to-day maintenance	Filmjölk
A culture to share and multiply over the years	Both

Which One Would I Recommend?

If you enjoy experimenting and don't mind separating kefir grains, milk kefir is a rewarding culture to keep.  I have kept milk kefir going for years, and I would be really upset if I ever lost it.  I drink milk kefir, I use it on my breakfast in the morning, and use it to make tvorog.

If you want something mild, simple, and easy to maintain, filmjölk is hard to beat.  Given its simplicity, and its mild flavour,  I'm surprised this isn't more commonly made by people at home.

Personally, I don't think it is an either/or decision.

I make both regularly because I like them both and they suit different situations.

I ferment filmjölk with the lid on

Making Kefir and Filmjölk in the Same Kitchen

One question I often get is whether it is possible to make both milk kefir and filmjölk in the same kitchen.

For me, the answer is yes.  I have kept several cultures including milk kefir, kombucha, and filmjölk all going at the same time for years, but I do treat them as separate cultures and take care not to mix them.

I don't share utensils between my kefir and filmjölk.  Each culture has its own jar, spoon, and strainer, which helps reduce the chance of accidentally transferring one culture into the other.

I also handle them slightly differently.  My milk kefir is usually left uncovered while it ferments, which is how I have always made it.  I have always been told that milk kefir is an aggressive culture, and can contaminate other nearby cultures.  My filmjölk is kept covered with a lid while it ferments.

Keeping the filmjölk covered gives me peace of mind that it is less likely to pick up anything from the surrounding environment, especially since I have other active fermented cultures sitting nearby.  

The two cultures are quite different.  Milk kefir grains contain a complex community of bacteria and yeasts, while filmjölk relies on specific lactic acid bacteria.  I like how each tastes, and I like how each has different uses.  I prefer to keep those communities separate rather than risk one gradually changing the other.

My kitchen is not a laboratory, and fermented foods have been made in ordinary kitchens for generations.  However, treating each culture with care makes it easier to keep them healthy and consistent over time.

Where Can You Buy Kefir Or Filmjölk Cultures?

If you want to try making either one, you will need a starter culture.

For kefir, you can start with live milk kefir grains.

For filmjölk, you can use a filmjölk starter culture if you don't have someone nearby who can share some fresh starter.

Both cultures can continue producing batch after batch when cared for properly and can be kept going indefinitely.

I ferment kefir with the lid off

My Recommendation For Beginners

If you have never fermented milk before, start with whichever culture is easiest for you to obtain.

Both are inexpensive to make, forgiving, and require very little equipment.  Both taste great, both have purported health benefits, and both taste remarkably different to one another.

Once you have mastered one, trying the other is very straightforward.

Fermentation Books I Recommend

If you are interested in making kefir, filmjölk, or other fermented foods at home, these are some books I have found useful.

The Art of Fermentation by Sandor Ellix Katz

This is one of the best-known fermentation books and covers a huge range of traditional fermented foods.  It goes well beyond milk fermentation into vegetables, drinks, and other cultures.
Check the current price on Amazon

Wild Fermentation by Sandor Ellix Katz

This is a more approachable introduction to fermentation.  I like it because it focuses on the idea that fermentation has been part of everyday kitchens for thousands of years.
Check the current price on Amazon

Super Gut by William Davis

This book focuses more on gut health and fermented foods.  Some of the health claims are debated, but it contains interesting information about fermented foods and probiotic cultures.
Check the current price on Amazon

Continue Your Fermentation Journey

• Beginner Guide to Making Milk Kefir at Home
• Beginner Guide to Growing Milk Kefir Grains at Home
• How To Make Farmer's Kefir Cheese (Tvorog)
• My Filmjölk Guide

Final Thoughts

After making both milk kefir and filmjölk in my own kitchen, I don't think one is universally better than the other.  They simply suit different people and different situations.

If you enjoy a stronger flavour, want the resilience of kefir grains, or like experimenting with fermented foods, milk kefir is an excellent choice.  If you're looking for something incredibly simple with a mild flavour that the whole family is more likely to enjoy, filmjölk is hard to beat.

In our house, I now keep both cultures going.  Kefir remains my favourite (largely for sentimental reasons), while filmjölk has become the cultured milk my children ask for most often.  Fortunately, they're both easy to maintain, so there's no reason I can't make both.