★ SOSA reed diffusers · winter
Winter gives you weeks you did not ask for and takes presence you did — so winter is the season to add reeds, not remove them
★ ★ ★ ★ ★
★★★★★
"A bottle that should have finished in eight weeks was still going at eleven, and I had convinced myself it had failed. It had simply slowed down."
Evening Calm 50ml
★★★★★
"Adding two reeds in December was the only time adding reeds has ever felt free. The bottle still outlasted its window."
Reed count · winter
★★★★★
"Warm scents genuinely read better in cold rooms. Fresh Brew in January is a different experience from Fresh Brew in May."
Fresh Brew 130ml
★★★★★
"My flat is shut tight all winter and I had stopped noticing the fragrance entirely. Guests could smell it the moment they walked in."
Adaptation · winter
★★★★★
"Being told the slow bottle was normal, rather than being sold a stronger one, is why I came back for the refill."
300ml refill ₹2,399
★★★★★
"Seven reeds through the cold months, back to six in spring. Small change, noticeably better room."
Mountain Breeze 50ml
★★★★★
"A bottle that should have finished in eight weeks was still going at eleven, and I had convinced myself it had failed. It had simply slowed down."
Evening Calm 50ml
★★★★★
"Adding two reeds in December was the only time adding reeds has ever felt free. The bottle still outlasted its window."
Reed count · winter
★★★★★
"Warm scents genuinely read better in cold rooms. Fresh Brew in January is a different experience from Fresh Brew in May."
Fresh Brew 130ml
★★★★★
"My flat is shut tight all winter and I had stopped noticing the fragrance entirely. Guests could smell it the moment they walked in."
Adaptation · winter
★★★★★
"Being told the slow bottle was normal, rather than being sold a stronger one, is why I came back for the refill."
300ml refill ₹2,399
★★★★★
"Seven reeds through the cold months, back to six in spring. Small change, noticeably better room."
Mountain Breeze 50ml
✓ Six fibre reeds per bottle · add one or two in the cold months, remove them in the heat ✓ 50ml lasts 6–8 weeks · 130ml lasts 14–18 weeks · the long end in cool weather ✓ Phthalate-free heat-stable CCT base · handmade in Pune · free shipping above ₹499
Founder Diaries · Reed Diffusers · Winter
And quieter: cold air is denser and more still, convection is weaker, and a winter house is usually shut. Less of what does leave the reeds travels to where you are sitting.
The winter move: add one or two reeds — seven or eight instead of six. In any other season that costs you weeks; in the cold months the slower rate largely absorbs it, which makes this the cheapest presence you will buy all year.
Choose warm over cold: a cool room flatters deep, warm compositions. Fresh Brew at ₹849 and Garden Bloom at ₹799 read fuller in January than the sharp cold ones do.
Garden Bloom₹799 · 8.9/10A reed diffuser has no fan and no propulsion; it depends entirely on the room's own air movement to carry fragrance away from the glass. Warm air rises and sets up gentle convection; cold air is denser and moves less on its own. So a cold room is doing less of the distribution work at exactly the moment the reeds are releasing less to distribute. A winter home compounds it: windows closed, doors shut to keep heat in, curtains drawn, no cross-ventilation. The fragrance pools near the bottle and the person on the sofa receives very little of it. That is not weakness in the composition; that is a room not carrying.
Fresh Brew · warm-deep, 9.5from ₹849Shop → 
Garden Bloom · rounded floralfrom ₹799Shop → 
Warmth & Bloom duo₹1,598 / 2 × 50mlShop →
SOSA reed diffuser range & prices (verified August 2026): alcohol-free, phthalate-free, paraben-free and IFRA-compliant compositions on a heat-stable coconut-derived (CCT) carrier, low-VOC, supplied in a refillable glass bottle with six fibre reeds; 50ml lasts 6–8 weeks and 130ml lasts 14–18 weeks. Morning Freshness (Malabar lemon · peppermint · Nilgiri eucalyptus) 50ml ₹749 · 130ml ₹1,249 · 9.0/10; Garden Bloom (British rose · night-blooming jasmine) 50ml ₹799 · 130ml ₹1,299 · 8.9/10; Evening Calm (Kashmir lavender · chamomile) 50ml ₹799 · 130ml ₹1,299 · 8.9/10; Fresh Brew (Coorg coffee · Kerala vanilla) 50ml ₹849 · 130ml ₹1,349 · 9.5/10; Mountain Breeze (Himalayan pine · sage · Indian cedar) 50ml ₹849 · 130ml ₹1,349 · 9.4/10. Reed diffuser refills are oil only — you reuse your own vessel and reeds: 300ml ₹2,399 (roughly 8–11 months) · 500ml ₹3,499 (roughly 14–18 months), about ₹7–8 per ml against ₹15–17 per ml for a 50ml bottle. Duo sets ₹1,498–₹1,598 for 2 × 50ml and ₹2,498–₹2,598 for 2 × 130ml. Strength figures are positions on SOSA’s own internal strength scale, not an industry standard. Replacement reeds are not sold as a separate SKU; SOSA guidance is to refresh reeds every few months. The reed line is separate from the water-based Hotel Collection for ultrasonic machines (15ml ₹299 · 100ml ₹999 · 300ml ₹1,799) and the two are not interchangeable. Diffusers: Boond 300ml ₹899 · Sukoon 500ml ₹1,899 · Megh 6L ₹3,499 · waterless Vaayu ₹11,999. Composed and handmade in small batches in Pune, India; tested through 45°C summer heat and 85% monsoon humidity. Free shipping above ₹499. A portion of every order supports girl-child education through Nanhi Kali. Prices subject to change — see the live product pages.
Yes — and I want to give you the second half of that sentence too, because on its own it sounds like unambiguously good news. Cold air slows evaporation, so your bottle lasts longer; and cold, dense, still air also carries fragrance less readily, so the room reads quieter. Those are the same cause producing two opposite feelings. You gain weeks you did not particularly want and lose presence you did. Which is why winter is the one season where I actively recommend adding reeds rather than taking them out.
Quick answers — read this first
Yes, longer: lower temperature means less oil leaves the reeds per hour. Expect a 50ml to sit at the long end of its 6–8 week window in the coldest weeks, and a 130ml at the long end of 14–18.And quieter: cold air is denser and more still, convection is weaker, and a winter house is usually shut. Less of what does leave the reeds travels to where you are sitting.
The winter move: add one or two reeds — seven or eight instead of six. In any other season that costs you weeks; in the cold months the slower rate largely absorbs it, which makes this the cheapest presence you will buy all year.
Choose warm over cold: a cool room flatters deep, warm compositions. Fresh Brew at ₹849 and Garden Bloom at ₹799 read fuller in January than the sharp cold ones do.
The short answer
Short answer: yes, reed diffusers last longer in winter — and they also read quieter, for the same reason. Slower evaporation preserves the oil and reduces how much fragrance is entering the room per hour. If you want your winter room to smell as it did in autumn, you have to put something back, and the cheapest thing to put back is reeds.
The mechanism: evaporation is temperature-driven, so a cold room takes less oil off the same six fibre reeds. On top of that, cold air is denser and rises less, so it moves less on its own — and a winter home tends to be shut against the cold, which removes the air exchange that would otherwise distribute the fragrance. Three effects, all pointing the same way.
Shop: for cold months, warm-deep compositions carry best — Fresh Brew at ₹849, Garden Bloom at ₹799, or both together as the Warmth & Bloom duo at ₹1,598 for 2 × 50ml. Free shipping above ₹499.
In this guide
Warm-deep, made for cold rooms
Fresh Brew 9.5 · from ₹849
Rounded and hotel-like
Garden Bloom · from ₹799
Two warm sources
Warmth & Bloom duo · ₹1,598
Straight answer
Do reed diffusers last longer in winter, and is that a good thing?
1. Yes, they last longer — that part is straightforwardly true. Lower temperature means fewer molecules leave the exposed reed surface per hour. In the coldest weeks expect a 50ml to run at the long end of its 6–8 week window and a 130ml at the long end of 14–18.
2. And they read quieter, which is the half that catches people out. The same slow rate that saves your oil is also the rate at which fragrance enters the room. Less is arriving. On a cold evening in a shut flat, considerably less is arriving where you are actually sitting.
3. So winter is the season to add reeds, not remove them. Seven or eight instead of six. In hot weather that trade costs you real weeks; in cold weather the underlying rate is low enough that you can raise the exposed surface and still finish the season inside the stated window. It is the closest thing to free presence this format offers.
4. Choose warmth over sharpness for the cold months. A cool room flattens bright, cold, citric compositions and flatters deep warm ones. Fresh Brew at 9.5 on our internal scale and Garden Bloom at 8.9 both read fuller in January than they do in May, and Mountain Breeze at 9.4 is the dry answer if you want no sweetness at all.
5. Do not mistake a slow bottle for a failed one. A bottle that has barely gone down after six weeks in a cold room is behaving correctly. Lift a reed and check the wet-line before you conclude anything: if the boundary is sitting high and dark, flip all six; if it is barely above the oil, the reeds may be spent.
Composed and handmade in small batches in Pune, and a portion of every order supports girl-child education through Nanhi Kali.
2. And they read quieter, which is the half that catches people out. The same slow rate that saves your oil is also the rate at which fragrance enters the room. Less is arriving. On a cold evening in a shut flat, considerably less is arriving where you are actually sitting.
3. So winter is the season to add reeds, not remove them. Seven or eight instead of six. In hot weather that trade costs you real weeks; in cold weather the underlying rate is low enough that you can raise the exposed surface and still finish the season inside the stated window. It is the closest thing to free presence this format offers.
4. Choose warmth over sharpness for the cold months. A cool room flattens bright, cold, citric compositions and flatters deep warm ones. Fresh Brew at 9.5 on our internal scale and Garden Bloom at 8.9 both read fuller in January than they do in May, and Mountain Breeze at 9.4 is the dry answer if you want no sweetness at all.
5. Do not mistake a slow bottle for a failed one. A bottle that has barely gone down after six weeks in a cold room is behaving correctly. Lift a reed and check the wet-line before you conclude anything: if the boundary is sitting high and dark, flip all six; if it is barely above the oil, the reeds may be spent.
Composed and handmade in small batches in Pune, and a portion of every order supports girl-child education through Nanhi Kali.
TL;DR: yes, cold weather makes a bottle last longer — and makes the room read quieter, because it is the same slow rate doing both. Add one or two reeds for the cold months, choose a warm-deep composition over a sharp cold one, and remember that a slow bottle in January is working exactly as designed.
The composition a cold room flatters
SOSA Fresh Brew · Coorg coffee & Kerala vanilla ₹849 / 50ml
Warm-deep compositions hold together in cool air in a way that bright citric ones do not — there is more weight in them to carry, and a cold room does not thin them out the way it thins a lemon. Roasted Coorg coffee over Kerala vanilla, 9.5 on our internal strength scale at six reeds, which is the highest in the range. Alcohol-free, phthalate-free and low-VOC on a heat-stable coconut-derived CCT base, with six fibre reeds in a refillable glass bottle. 130ml ₹1,349 for 14–18 weeks, which in a cold season will comfortably reach the top of that window.
Part one — the double effect of cold air
Every seasonal article about diffusers stops at "they last longer in winter" and treats that as the whole answer, which is how people end up puzzled in February with a bottle that is nearly full and a room that smells of nothing. Slow evaporation is not a benefit and a fact; it is a benefit and a cost, arriving together, from one cause. Below, the three things cold does — two of them working on the physics of release and one working on the room — and then the practical response, which runs opposite to the summer one in every particular.
1
EFFECT ONE · THE GAIN
Less oil leaves the reeds per hour
Evaporation is driven by temperature: molecules need energy to leave a liquid surface, and a cold room supplies less of it. The oil still climbs the six fibre reeds perfectly well — capillary action is not much bothered by a mild chill — but it departs from the exposed end more slowly. The visible result is a bottle level that seems almost stationary, and a 50ml that comfortably reaches or exceeds the long end of its 6–8 week window. The only thing to guard against is misreading it: a slow bottle looks identical to a stalled one from across a room, and the two are entirely different conditions. The reed will tell you which you have — a stalled reed is dark and saturated high up its length, while a slow one looks ordinary and its wet-line moves, gradually, over days.
The check: a slow bottle in cold weather is healthy. A dark, heavy, high-wet-line reed is stalled and wants flipping, whatever the season.
2
EFFECT TWO · THE COST
Cold, dense, still air distributes less
Garden Bloom₹799 · 8.9/10A reed diffuser has no fan and no propulsion; it depends entirely on the room's own air movement to carry fragrance away from the glass. Warm air rises and sets up gentle convection; cold air is denser and moves less on its own. So a cold room is doing less of the distribution work at exactly the moment the reeds are releasing less to distribute. A winter home compounds it: windows closed, doors shut to keep heat in, curtains drawn, no cross-ventilation. The fragrance pools near the bottle and the person on the sofa receives very little of it. That is not weakness in the composition; that is a room not carrying.
The tell: obvious at the bottle, nothing at the sofa. In winter that is nearly always air, not fragrance.
3
THE RESPONSE
Add reeds — the one season where it is close to free
Reed count is the only true throughput control on a passive diffuser, and adding reeds always costs bottle life in roughly the proportion it adds presence. In a hot month that trade bites hard. In the cold months the underlying rate is already low, so raising the exposed surface brings the room back up without taking the bottle outside its stated window. Seven or eight reeds instead of six through the coldest weeks is my own winter setting, and I take the extras out when the weather turns. Two notes. More reeds means more surface accumulating heavy residue, so keep flipping all of them weekly with gloves on. And this is a seasonal adjustment rather than a permanent one — six is the count each composition is dosed for, and where every strength figure we publish is measured.
Part two — the same bottle, hot months against cold
Set side by side, the two seasons ask for almost exactly opposite behaviour from the owner. This is the table I would pin somewhere, because every line in it reverses.
One bottle, two seasons
Everything that reverses between hot weather and cold
| Variable | Hot months | Cold months | What you do about it |
|---|---|---|---|
| Evaporation rate ★ | High — molecules leave the reed readily | Low — less energy to leave with | Reeds down in heat, reeds up in cold |
| Bottle life against the stated window | Short end — 50ml nearer six weeks | Long end — 50ml at or beyond eight | Buy 130ml for a hot season, 50ml for a cold one |
| How the room reads | Fuller, sometimes top-heavy | Quieter, and slower to build | Add a reed or two in winter before adding a bottle |
| Air movement in the house | Fans, AC, some windows open | Shut tight, curtains drawn, little exchange | Leave an internal door open; place near a walkway |
| Which compositions flatter the season | Cold and dry — Morning Freshness, Mountain Breeze | Warm and deep — Fresh Brew, Garden Bloom | Rotate scent with the season, not the bottle size |
| Flip cadence | Weekly, without exception at high reed counts | Weekly still — residue accumulates regardless of rate | Same either way; gloves on, tray underneath |
| The commonest wrong conclusion | "The oil is evaporating too fast, it must be thin" | "It has stopped working, the bottle is still full" | Wet-line test first, then airflow, then reeds |
| The honest caveat: "winter" means very different things across India — a Shimla January and a Chennai January are not the same instruction, and much of the south and the coast never reaches the temperatures this page describes. Read the left column as a description of your weather rather than a month. We give no figure for how many extra weeks cold weather buys you; it depends on room temperature, volume, ventilation and reed count, and the 6–8 and 14–18 week windows are SOSA working guidance across an ordinary year rather than laboratory numbers. | |||
Shop this guide
What I would have standing through a cold season
Fresh Brew · warm-deep, 9.5from ₹849Shop → Garden Bloom · rounded floralfrom ₹799Shop → Warmth & Bloom duo₹1,598 / 2 × 50mlShop →
The SOSA principle
Winter does not make your diffuser weak. It makes it slow — and slow reads as weak from the sofa.
The gain and the cost are the same fact. Take the extra weeks, and put a reed or two back in to pay for the quiet.
Part three — the winter nose, and the sealed room
There is a third thing happening in a cold season that has nothing to do with evaporation at all, and it is responsible for a good share of the "it stopped working in December" emails I receive. Olfactory adaptation is the mechanism by which your nose stops reporting a smell that does not change. It is fast, often a matter of minutes, and strongest in the place you spend most time. A winter house makes it worse in two ways: you are indoors far more of the day, and the fragrance is genuinely more constant because the air is not being exchanged. The result is a bottle everyone who walks through your front door remarks upon and you cannot detect at all. Before you spend anything, go out for fifteen minutes and come back in, or ask a guest plainly. They are the better instrument.
The sealed room also cuts the other way, and this is the nuance that most seasonal advice misses. A closed house does not merely fail to distribute — it also concentrates. In a small, shut bedroom in the middle of winter, a fragrance can build to a level that would be perfectly pleasant in an open living room and is rather too much in there. So the correct winter instruction is not "add reeds everywhere": add reeds in the large, cold, open spaces where fragrance is being lost, and leave the small sealed rooms alone or take a reed out. Evening Calm at 8.9 on our scale, with four reeds, in a closed winter bedroom, is a deliberately quiet configuration and the right one for most people who want to sleep rather than to be scented. Strength figures throughout are positions on SOSA's own internal scale measured at six reeds — not an industry standard, not a concentration, and not a ranking of quality.
One last piece of winter housekeeping, since the season invites it: this is a good time to think about your reeds rather than your oil. Most people have the relationship backwards, replacing the fragrance and keeping the sticks, when the sticks are the consumable and the oil is the stable part. If your bottle has run since the previous summer, the reeds have done a full hot season and are the likelier limiting factor. Our guidance is to refresh reeds every few months, and here is the honest gap in our range, stated plainly: we do not sell replacement reeds as a separate item, so a fresh set of six arrives with a new bottle. The oil-only refill at ₹2,399 for 300ml is excellent value at roughly ₹7–8 per millilitre against ₹15–17, but it does not include reeds.
The bottle lasting longer and the room going quiet are the same sentence, read from two ends.
— Sonal Sahani, SOSA
Part four — the winter edit
Organised by the situation you are actually in, because a cold open living room and a cold shut bedroom want opposite treatment.
The winter edit
By room and situation, with the reed setting for each
| Winter situation | What is happening | Reed setting | What I would run |
|---|---|---|---|
| Large cold living room, everything shut ★ | Slow release plus air that will not carry it | 7–8 reeds | Fresh Brew from ₹849 — warm-deep and the loudest we make |
| Entryway or hall in the cold months | Cold draught at the door strips reeds; brief exposure for guests | 6, placed off the draught line | Garden Bloom ₹799 — rounded, hotel-like, reads instantly |
| Small sealed bedroom | Concentration rather than dispersal — the reverse problem | 4, sometimes 3 | Evening Calm ₹799 — the softest thing in the range |
| Home office or study, cold and still | You adapt within minutes of sitting down | 6–7 | Mountain Breeze ₹849 — dry, grounding, no sweetness |
| Open living-dining, one bottle in the middle | Output per bottle is fixed; distance defeats it | 6 in each of two bottles | Warmth & Bloom duo ₹1,598 — two warm sources that share a note |
| Bottle running since last summer | Reeds are the tired component, not the oil | Fresh six | A new bottle for new reeds; refill ₹2,399 for oil alone |
| You want scent only on some evenings | Beyond what any passive format can do | — | Sukoon ₹1,899 · 270–320 sq ft · timers · three scents in the box |
Honest notes for buyers: bottle-life windows are SOSA working guidance across an ordinary Indian year — 50ml 6–8 weeks, 130ml 14–18 weeks at six fibre reeds — and cool weather sits at the long end of them. Seasonal descriptions here are general climate framing and will not map onto every part of India. Strength figures are positions on SOSA's own internal scale at six reeds, not an industry standard, not a concentration and not a quality ranking. A 130ml is a longer bottle, never a louder one. Refills are oil only and do not include reeds; replacement reeds are not sold separately, which is an honest gap, and guidance is to refresh them every few months. The range is alcohol-free, phthalate-free, paraben-free, low-VOC and IFRA-compliant on a heat-stable coconut-derived CCT base tested through 45°C heat and 85% humidity. Reed oil never goes into a Sukoon or Boond, and the water-based Hotel Collection never goes into a reed bottle. Stand the bottle on a tray; keep away from children and pets.
Two warm sources for a cold, shut flat
SOSA Warmth & Bloom duo · Fresh Brew + Garden Bloom ₹1,598 / 2 × 50ml
When the house is closed for the season, the limiting factor is not the fragrance but the fact that one point source cannot reach across a divided flat with no air moving through it. Output per bottle is fixed; the only way to raise the total in a home is another bottle. These two meet on warmth and a soft musk, so where the spaces overlap you get a join rather than a seam — coffee and vanilla at 9.5, rose and night-blooming jasmine at 8.9. 2 × 130ml ₹2,598 for 14–18 weeks apiece.
SS
ISIPCA
Versailles
Versailles
A note from Sonal
Winter emails have a particular flavour. They arrive in January, they are polite, and they say some version of: the bottle is still nearly full but I do not think it is working any more. I understand the suspicion — a full bottle and a quiet room look exactly like a product that has failed, and nobody has explained that in cold weather those two things go together by necessity.
The design decision underneath this is one I stand by: our compositions sit at a level they can hold for the whole life of the bottle rather than opening loudly and fading. A flat, honest plateau is easier to live with, but it does mean the fragrance does not announce itself, and in a cold sealed room with a nose that has adapted to it, an honest plateau can be almost invisible from the inside.
So my winter advice is unglamorous. Add a reed or two in the big cold rooms. Leave an internal door open. Go outside for a quarter of an hour and walk back in, and believe what your nose says in the first ten seconds rather than what it says after ten minutes. Everything is composed and handmade in small batches in Pune, and a part of every order funds a girl's classroom through Nanhi Kali.
Frequently asked questions
Do reed diffusers really last longer in winter?
Yes. Evaporation is temperature-driven, so a cold room takes less oil off the same six reeds per hour. Expect a 50ml to sit at or beyond the long end of its 6–8 week window and a 130ml at the long end of 14–18. That is normal behaviour, not a stalled bottle — check the wet-line on a reed if you want to be sure.
Why does my reed diffuser smell weaker in winter?
Three reasons, all pointing the same way. Slower evaporation means less fragrance entering the room; cold, dense air distributes badly; and a winter house is shut, removing the air exchange that would carry it. Your nose also adapts hardest to an unvarying fragrance at home. None of these is a fault in the bottle.
Should I add more reeds in winter?
Yes, in the large cold rooms — seven or eight instead of six. Adding reeds always trades bottle life for presence, but in cold weather the underlying rate is low enough that the trade is far gentler than it would be in May. Take the extras out when the weather turns. Keep flipping all of them weekly, gloves on.
Which fragrance works best in cold weather?
Warm and deep ones. Fresh Brew at 9.5 on our internal scale and Garden Bloom at 8.9 both read fuller in a cool room than bright citric compositions do, because there is more weight in them for cold air to carry. Mountain Breeze at 9.4 is the choice if you want that presence with no sweetness at all.
My bottle is still full after two months — is it faulty?
Almost certainly not, if the weather is cold. Lift one reed with gloves on and find the wet-line. If it sits high and the reed looks dark and heavy, delivery has stalled and all six want flipping. If it is barely above the oil after days in the bottle, the reeds may be spent — refresh them. If it looks ordinary and has moved over the week, you simply have a slow winter bottle behaving correctly.
Reed diffusers in winter · 2027
Take the extra weeks. Then put a reed or two back in to pay for the quiet
SOSA reed diffusers from ₹749 for 50ml (6–8 weeks) and ₹1,249 for 130ml (14–18 weeks), six fibre reeds in a refillable glass bottle, alcohol-free and phthalate-free on a heat-stable coconut-derived CCT base tested through 45°C heat and 85% humidity. Warm-deep compositions for cold rooms: Fresh Brew at 9.5 and Garden Bloom at 8.9, or both as the Warmth & Bloom duo at ₹1,598. Free shipping above ₹499, and a portion of every order supports girl-child education through Nanhi Kali.
Shop warm compositions → Warmth & Bloom duo ₹1,598
Continue the read
More on weather and reed diffusers
- Do reed diffusers evaporate faster in summer? — the same two dials, turned the other way.
- Does hot weather affect reed diffusers? — heat's two separate effects.
- Using SOSA diffusers across Indian seasons and why can't I smell my reed diffuser?
- The complete weather and climate guide — this page and the eight around it, in one place.
- Brand: the SOSA founder story.
Editorial standards & sources
About this guide: Written by Sonal Sahani, ISIPCA Versailles-trained founder and perfumer at SOSA Home & Body, on why cold weather both extends a reed diffuser's life and reduces its presence in a room. Bottle-life windows (50ml 6–8 weeks, 130ml 14–18 weeks at six fibre reeds) and the guidance to refresh reeds every few months are SOSA working guidance from in-house testing and customer correspondence, not laboratory measurements. Descriptions of cold, dense, still air distributing fragrance less readily, and of Indian winters generally, are general climate framing and perfumery principle rather than measurements for any particular city — much of India does not experience the conditions described, and we give no figure for how many extra weeks cold weather buys, because it depends on room temperature, volume, ventilation and reed count. Strength ratings are positions on SOSA's internal scale at six reeds, not an industry standard.SOSA reed diffuser range & prices (verified August 2026): alcohol-free, phthalate-free, paraben-free and IFRA-compliant compositions on a heat-stable coconut-derived (CCT) carrier, low-VOC, supplied in a refillable glass bottle with six fibre reeds; 50ml lasts 6–8 weeks and 130ml lasts 14–18 weeks. Morning Freshness (Malabar lemon · peppermint · Nilgiri eucalyptus) 50ml ₹749 · 130ml ₹1,249 · 9.0/10; Garden Bloom (British rose · night-blooming jasmine) 50ml ₹799 · 130ml ₹1,299 · 8.9/10; Evening Calm (Kashmir lavender · chamomile) 50ml ₹799 · 130ml ₹1,299 · 8.9/10; Fresh Brew (Coorg coffee · Kerala vanilla) 50ml ₹849 · 130ml ₹1,349 · 9.5/10; Mountain Breeze (Himalayan pine · sage · Indian cedar) 50ml ₹849 · 130ml ₹1,349 · 9.4/10. Reed diffuser refills are oil only — you reuse your own vessel and reeds: 300ml ₹2,399 (roughly 8–11 months) · 500ml ₹3,499 (roughly 14–18 months), about ₹7–8 per ml against ₹15–17 per ml for a 50ml bottle. Duo sets ₹1,498–₹1,598 for 2 × 50ml and ₹2,498–₹2,598 for 2 × 130ml. Strength figures are positions on SOSA’s own internal strength scale, not an industry standard. Replacement reeds are not sold as a separate SKU; SOSA guidance is to refresh reeds every few months. The reed line is separate from the water-based Hotel Collection for ultrasonic machines (15ml ₹299 · 100ml ₹999 · 300ml ₹1,799) and the two are not interchangeable. Diffusers: Boond 300ml ₹899 · Sukoon 500ml ₹1,899 · Megh 6L ₹3,499 · waterless Vaayu ₹11,999. Composed and handmade in small batches in Pune, India; tested through 45°C summer heat and 85% monsoon humidity. Free shipping above ₹499. A portion of every order supports girl-child education through Nanhi Kali. Prices subject to change — see the live product pages.