★ SOSA reed diffusers · summer placement
Summer placement is a heat audit, not a decorating decision — find the coolest surface in the room and the bottle looks after itself
★ ★ ★ ★ ★
★★★★★
"Mine sat on the west windowsill and emptied in five weeks flat. Moved it to the inner hallway shelf and the next bottle went the full eight."
Garden Bloom 50ml
★★★★★
"I never thought of the TV console as a heat source until I put my hand on it at nine at night. Moved the diffuser one shelf down."
Mountain Breeze 130ml
★★★★★
"The palm test at four in the afternoon is such a simple idea. Two of my four spots failed it."
Summer placement audit
★★★★★
"It was directly under the split AC. Cool, yes, but the reeds were being blasted all day and the room smelled of nothing."
Placement · AC draught
★★★★★
"North-facing bedroom shelf, away from the window, five reeds through May. Evening Calm actually lasted the season."
Evening Calm 50ml
★★★★★
"Standing it on a small tray saved my sideboard. I had not realised the oil marks stone until it nearly did."
Tray · care advice
★★★★★
"Mine sat on the west windowsill and emptied in five weeks flat. Moved it to the inner hallway shelf and the next bottle went the full eight."
Garden Bloom 50ml
★★★★★
"I never thought of the TV console as a heat source until I put my hand on it at nine at night. Moved the diffuser one shelf down."
Mountain Breeze 130ml
★★★★★
"The palm test at four in the afternoon is such a simple idea. Two of my four spots failed it."
Summer placement audit
★★★★★
"It was directly under the split AC. Cool, yes, but the reeds were being blasted all day and the room smelled of nothing."
Placement · AC draught
★★★★★
"North-facing bedroom shelf, away from the window, five reeds through May. Evening Calm actually lasted the season."
Evening Calm 50ml
★★★★★
"Standing it on a small tray saved my sideboard. I had not realised the oil marks stone until it nearly did."
Tray · care advice
✓ Heat-stable coconut-derived CCT base · tested through 45°C summer heat ✓ Phthalate-free — no cheap solvent to turn acrid in a Delhi June ✓ Six fibre reeds per bottle · 50ml 6–8 weeks · 130ml 14–18 weeks · handmade in Pune
Founder Diaries · Reed Diffusers · Summer Placement
The worst: a west- or south-facing windowsill. Direct sun both heats the oil and strips the reeds, so you lose weeks of bottle life and get a thinner room while you do.
The heat sources people miss: the top and sides of a fridge, a TV or set-top box, a router shelf, a laptop, an inverter, and the wall behind a geyser. Put a palm on the surface at four in the afternoon before you trust it.
What is not the answer: a bigger bottle. A 130ml lasts 14–18 weeks against 6–8, but at the same six reeds it projects the same. In heat, placement buys you far more than size.
Mountain Breeze₹849 · 9.4/10Put your palm flat on the top of your fridge at nine in the evening. Then on the TV console where the set-top box lives, then on the shelf holding the router, then beside the inverter. In most Indian flats at least two of those are noticeably warm for twelve or more hours a day — a far longer exposure than a two-hour patch of sun. A diffuser sitting on a permanently warm appliance is being run at an elevated rate around the clock. The fix is usually trivial: one shelf down, or eighteen inches along. Kitchens deserve a separate mention — the counter beside the hob is warm, greasy and directly in the path of cooking smells, and it is the single worst kitchen placement even though it is the most common.
Mountain Breeze · 9.4/10from ₹849Shop → Evening Calm · 8.9/10from ₹799Shop → 
Day & Night duo₹1,498Shop →
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.
Most placement advice is written for a temperate room. It talks about doorways and eye level and passing traffic, all of which is true, and none of which is the first question in an Indian April. In hot weather the first question is temperature — specifically, the temperature of the surface the bottle is standing on and the wall behind it. Heat raises the rate at which oil leaves the reed, so a bottle on a sun-warmed sill empties weeks early and gives you a hot, top-heavy version of the fragrance while it does. This page is a summer placement audit: how to find the coolest genuinely useful surface in each room, and which apparently sensible spots quietly cook your diffuser.
Quick answers — read this first
The best summer spot: a console, shelf or sideboard against an interior wall, near a doorway or walkway, at roughly waist to chest height, out of any direct sun and several feet clear of an AC vent or fan.The worst: a west- or south-facing windowsill. Direct sun both heats the oil and strips the reeds, so you lose weeks of bottle life and get a thinner room while you do.
The heat sources people miss: the top and sides of a fridge, a TV or set-top box, a router shelf, a laptop, an inverter, and the wall behind a geyser. Put a palm on the surface at four in the afternoon before you trust it.
What is not the answer: a bigger bottle. A 130ml lasts 14–18 weeks against 6–8, but at the same six reeds it projects the same. In heat, placement buys you far more than size.
The short answer
Short answer: keep a reed diffuser on the coolest, most shaded, most stable surface that still sits in gently moving air — an interior-wall console near a doorway is the classic answer, ideally in a north-facing room. Away from direct sun, away from appliances and electronics that radiate heat, and several feet away from the draught of a split AC or a ceiling fan, which is a different failure with the same symptom.
The mechanism: oil climbs the fibre reed and evaporates from the exposed surface, and warmth speeds that up. A bottle standing in a 40°C patch of afternoon sun is being run hard all day whether or not anyone is in the room, so the 50ml that should have given you six to eight weeks gives you four or five — and because the lightest notes leave first and fastest, the room reads sharper and less balanced while it happens.
Shop: for hot months, Mountain Breeze at ₹849 gives you dry pine and cedar that stay cool in a warm room, and Evening Calm at ₹799 suits a hot bedroom. All our reed compositions sit on a heat-stable coconut-derived CCT base tested through 45°C. Free shipping above ₹499.
In this guide
Dry and cool in a warm room
Mountain Breeze 9.4 · from ₹849
For a hot bedroom
Evening Calm 8.9 · from ₹799
When summer runs bottles down
300ml oil refill · ₹2,399
Straight answer
Where should I keep a reed diffuser in hot weather?
1. On an interior wall, not an exterior one. An outside wall — especially a west-facing one — absorbs sun all afternoon and radiates it back into the room well after dark. A shelf or console on an internal partition wall sits closer to room temperature all day and is the single easiest improvement most homes can make.
2. Out of every patch of direct sun, at every hour. Not just where the sun is when you happen to be looking. Direct sunlight heats the oil and strips the reeds; it is the fastest way to lose weeks of a bottle you paid for.
3. Several feet from anything that radiates heat. The fridge, the TV and its set-top box, a router, a laptop dock, an inverter, the wall a geyser is fixed to, the back of a microwave. These run warm for hours and are rarely thought of as heat sources.
4. But still in moving air. Cool and stagnant is not a win. The right spot is a console or sideboard near a doorway or walkway at waist to chest height, where household traffic stirs the air a few times an hour. Cool and airless simply means you cannot smell it.
5. Not under the AC, and not in front of a fan. This catches people who have correctly worked out that they want a cooler spot. A direct draught strips the reeds, empties the bottle early and leaves the room smelling of very little — the opposite of what you were after.
6. On a tray, always. Reed oil marks wood and stone, and a warm surface makes a spill spread further and faster. Keep the bottle away from children and pets while you are at it.
Composed and handmade in small batches in Pune, and a portion of every order supports girl-child education through Nanhi Kali.
2. Out of every patch of direct sun, at every hour. Not just where the sun is when you happen to be looking. Direct sunlight heats the oil and strips the reeds; it is the fastest way to lose weeks of a bottle you paid for.
3. Several feet from anything that radiates heat. The fridge, the TV and its set-top box, a router, a laptop dock, an inverter, the wall a geyser is fixed to, the back of a microwave. These run warm for hours and are rarely thought of as heat sources.
4. But still in moving air. Cool and stagnant is not a win. The right spot is a console or sideboard near a doorway or walkway at waist to chest height, where household traffic stirs the air a few times an hour. Cool and airless simply means you cannot smell it.
5. Not under the AC, and not in front of a fan. This catches people who have correctly worked out that they want a cooler spot. A direct draught strips the reeds, empties the bottle early and leaves the room smelling of very little — the opposite of what you were after.
6. On a tray, always. Reed oil marks wood and stone, and a warm surface makes a spill spread further and faster. Keep the bottle away from children and pets while you are at it.
Composed and handmade in small batches in Pune, and a portion of every order supports girl-child education through Nanhi Kali.
TL;DR: interior wall, north-facing room if you have one, no direct sun at any hour, several feet from appliances and electronics, several feet from the AC vent, waist to chest height near a doorway, standing on a tray. Placement is worth more in a hot month than any purchase you can make.
The hot-bedroom bottle
SOSA Evening Calm · Kashmir lavender & chamomile ₹799 / 50ml
The softest composition we make at 8.9 on our internal scale, and deliberately so — it is built to help you sleep rather than to announce itself. That matters in summer, because heat already lifts a fragrance and a hot bedroom can turn a mid-strength scent insistent by midnight. Stand it on an interior-wall shelf away from the window, run four or five reeds rather than six through the hottest weeks, and it stays a background. Alcohol-free and phthalate-free on the heat-stable CCT base. 130ml ₹1,299 for 14–18 weeks.
Part one — the three things that quietly make a surface hot
A room does not have one temperature. It has a warm side and a cool side, a wall that has been in the sun since noon and a wall that has not, a shelf beside a working appliance and a shelf beside nothing at all. In April and May those differences are large enough to change how long your bottle lasts. The skill is learning to read a room thermally rather than decoratively, because the prettiest surface in most Indian flats is the windowsill, and the windowsill is the worst place a reed diffuser can stand. Three things make a surface hot, and it is worth being able to name all three.
1
HEAT SOURCE ONE · THE WALL
Exterior walls store the afternoon and give it back at night
Brick, concrete and stone hold heat for hours. A west-facing exterior wall takes the full weight of the afternoon sun, keeps absorbing until sunset, and then radiates gently into the room for much of the evening — which is exactly the period when most people are home and judging their fragrance. An interior partition wall does none of that; it sits close to the average temperature of the flat all day. Moving a bottle from an exterior-wall console to an interior-wall one is a free change that can measurably lengthen a bottle in summer, and it costs you nothing in airflow if you pick a spot near a doorway. If your home has a north-facing room, that room is usually the coolest in the flat through the hot months and the natural home for the bottle you most want to protect.
The rule of thumb: if the wall is warm to the back of your hand at sunset, it is the wrong wall for a diffuser in May.
2
HEAT SOURCE TWO · THE APPLIANCES
The warmth nobody counts as warmth
Mountain Breeze₹849 · 9.4/10Put your palm flat on the top of your fridge at nine in the evening. Then on the TV console where the set-top box lives, then on the shelf holding the router, then beside the inverter. In most Indian flats at least two of those are noticeably warm for twelve or more hours a day — a far longer exposure than a two-hour patch of sun. A diffuser sitting on a permanently warm appliance is being run at an elevated rate around the clock. The fix is usually trivial: one shelf down, or eighteen inches along. Kitchens deserve a separate mention — the counter beside the hob is warm, greasy and directly in the path of cooking smells, and it is the single worst kitchen placement even though it is the most common.3
HEAT SOURCE THREE · THE SUN, MOVING
A shaded spot at ten is a blazing one at four
This is the trap that catches careful people. You choose a spot in the morning, it is comfortably in shade, and you never see it again until evening — by which time the sun has swung round, sat on the glass for two hours, and gone. Sun also arrives second-hand: reflected off a balcony's light-coloured tiles, off a neighbouring building's glazing, off a pale floor. Glass makes it worse, because a bottle on a sill is heated by the sun and by the warm pane behind it at once. Direct sunlight is the one placement error that costs you on both sides of the ledger — the reeds are stripped so the bottle empties weeks early, and the room reads thinner because the lightest, most volatile part of the composition is being driven off faster than the rest.
The check: look at the candidate surface at 10am, 2pm and 4pm on one clear day. That is the whole test.
Part two — the spot-by-spot summer audit
Every surface people actually use, ranked for hot weather, with the reason. The verdicts here are SOSA's working guidance from in-house testing and customer correspondence rather than laboratory measurement, and how badly a bad spot performs will depend on your floor, your aspect and how many hours of sun your building takes.
The summer placement audit
Seven common spots, judged for a 40°C week
| Where the bottle stands | What happens to it in a hot week | What the room gets | Summer verdict |
|---|---|---|---|
| Interior-wall console near a doorway ★ | Stays close to the flat's average temperature all day | Steady output, distributed by ordinary foot traffic | Best in the house — cool and moving air together |
| Shelf in a north-facing room, away from the window | Coolest room in most flats through the hot months | Long, even plateau; often beats the stated bottle window | Excellent, if the room gets any traffic at all |
| Hallway or landing shelf, waist to chest height | Usually internal, usually shaded, always walked past | Reaches adjoining rooms as people move through | Very good — the underused spot in most homes |
| TV console, router shelf or beside an inverter | Warm for twelve hours a day, not two | Elevated rate around the clock; bottle short by weeks | Move it one shelf down or a foot and a half along |
| Top of or beside the fridge | Motor heat plus a warm cabinet side | Same as above, and kitchen odours join in | Avoid. Use an opposite counter or a shelf by the door |
| Directly under a split AC or in front of a fan | Cool, but the reeds are in a permanent draught | Stripped reeds, an early-empty bottle, a quiet room | The cool-spot trap. Keep several feet clear |
| West- or south-facing windowsill | Direct sun plus a hot pane behind the glass | Thin, top-heavy fragrance; four to five weeks, not eight | The worst spot there is, in any season and worse in May |
| The honest caveat: the coolest surface in a flat is often inside a cupboard, and that is not a placement — it is a hiding place. A reed diffuser in a closed cabinet, an alcove or behind a sofa cannot reach the room at all, and no amount of thermal virtue makes up for it. You are looking for the coolest spot among those that have air moving past them, not the coolest spot full stop. | |||
Shop this guide
What I would run through a hot season
Mountain Breeze · 9.4/10from ₹849Shop → Evening Calm · 8.9/10from ₹799Shop → Day & Night duo₹1,498Shop →
The SOSA principle
In a hot month, where the bottle stands is worth more than what is in it.
A composition three points higher on the strength scale costs money. Moving the same bottle off a sun-warmed sill onto an interior shelf costs nothing and often adds two or three weeks to its life.
Part three — the one-day audit you can run this week
Here is the whole method, and it takes about a minute of attention three times in a day. Pick the three or four plausible homes for the bottle: the console by the door, the sideboard, the open shelf, the dressing table. At ten in the morning, at two, and again at four, put your palm flat on each for a couple of seconds. You are not measuring anything — you are looking for the ones that are noticeably warmer, and for any that has moved into a patch of sun since you last looked. Nearly every home has at least one candidate that fails between two and four o'clock, and it is usually the one that looked best at breakfast. Then do the same at nine in the evening, when exterior walls and appliances are giving back what they took in.
Of the surfaces that pass, choose the one closest to a doorway or a walkway, at roughly waist to chest height, with clear space around the neck of the bottle. That last detail matters more than people expect: a bottle pushed to the back of a shelf behind photo frames is in still air even if the room is not. And leave several feet between the bottle and a split AC or a ceiling fan running at speed. The cool-spot trap is real — I have had customers move a diffuser directly beneath their AC on perfectly sound reasoning about temperature, only to find the reeds stripped and the room silent within a fortnight, because a constant draught takes the fragrance away from the room rather than through it.
One more thing worth saying plainly, because it is the reason this advice is not simply cosmetic. Heat does two different things to a fragrance: it raises the evaporation rate, which shortens the bottle, and in a poorly built formula it changes what the fragrance smells like. Many diffuser oils on the market use phthalate solvents that push scent hard off a reed and win the first week convincingly — and then degrade in sustained heat and turn faintly acrid by around week six. SOSA's reed range is phthalate-free on a heat-stable coconut-derived CCT carrier, tested through 45°C summer heat and 85% monsoon humidity, which buys a smaller opening and a longer, flatter plateau. Good placement protects the first problem; the base protects the second. You need both, and only one of them is something you can fix after you have bought the bottle.
The prettiest surface in an Indian flat is the windowsill. It is also the one place a reed diffuser should never stand.
— Sonal Sahani, SOSA
Part four — the coolest useful surface in each room
Room by room, where I would put a bottle from roughly March through June — bearing in mind that the hot season starts and ends at very different times across the country, and this is general climate framing rather than a calendar. The reed counts are suggestions, not rules; six is the calibrated dose for every SOSA composition and dropping to four or five is a free, reversible way to slow a bottle down in heat.
The hot-season arrangement
Six rooms, the surface I would choose, and the one to abandon
| Room | The surface I would use in summer | The surface to give up | Reeds |
|---|---|---|---|
| Entryway ★ | Console against the internal wall beside the door | The shelf under a west-facing window or glass panel | Six |
| Living room | Sideboard on an interior wall in line with the main doorway | Coffee table in the sun path; the TV console | Six |
| Bedroom | Dressing table or shelf on the inner wall, away from the glass | Windowsill, and anywhere under the split AC | Four to five |
| Home office or study | An open shelf a metre or more from the desk | Beside the laptop, router or a warm monitor | Five to six |
| Kitchen | Shelf near the doorway, on the opposite side from the hob | The counter beside the hob; the top of the fridge | Six |
| Bathroom | A dry shelf away from the shower and the geyser wall | The window ledge, and any spot the geyser warms | Four to six by size |
Honest notes for buyers: the hot-season month range used above is general climate framing, not a SOSA measurement — the same weeks look completely different in Jaipur, Kochi and Shillong, and you should read the weather rather than the calendar. Reed-count suggestions and bottle-life effects in heat are SOSA working guidance from in-house testing, not laboratory figures. Strength ratings are positions on SOSA's own internal scale at six reeds, not an industry standard and not a concentration. Our reed compositions are alcohol-free, phthalate-free, paraben-free, low-VOC and IFRA-compliant on a heat-stable coconut-derived CCT carrier tested through 45°C heat and 85% humidity. Refills are oil only — you reuse your own glass vessel and reeds — and replacement reeds are not sold separately, which is an honest gap; our guidance is to refresh them every few months. Reed oil never goes into a Sukoon, Boond or Megh, and the water-based Hotel Collection never goes into a reed bottle. Stand every bottle on a tray, keep it out of direct sunlight, and keep it away from children and pets. Composed and handmade in small batches in Pune, and a portion of every order supports girl-child education through Nanhi Kali.
If summer has been finishing your bottles early
SOSA reed diffuser refill · oil only ₹2,399 / 300ml
Fix the placement first — that is free and it is usually most of the problem. But if you live somewhere that runs hot for a third of the year, the running cost is worth solving too. The refill is oil alone, so you keep your own glass vessel and reeds: roughly ₹7–8 per millilitre against ₹15–17 for a fresh 50ml bottle, which is up to about 55% less. A 300ml keeps a vessel going for around 8–11 months, the 500ml at ₹3,499 for 14–18. Remove the reeds, pour to the neck, return them, and flip once so both ends are coated.
SS
ISIPCA
Versailles
Versailles
A note from Sonal
When we were testing the range through a Pune summer, we ran identical bottles in the same flat on different surfaces — one on a west-facing sill, one on an interior hallway console, same six reeds, same day of filling. The gap between them was not subtle, and nothing about the fragrance was different. One had simply spent every afternoon being gently cooked. That test changed how I write our care card, and it is why placement comes before product on this page.
It also shaped the formula. A fragrance that is going to sit in an Indian room in May needs a carrier that does not sour under sustained heat, which is why we build on a coconut-derived CCT base and refuse phthalate solvents even though they would make our first week more impressive. The trade is honest and I would rather state it: a smaller opening, and a plateau that holds instead of turning.
If you do one thing after reading this, do the palm test at four in the afternoon. It takes a minute, it costs nothing, and in a hot month it is worth more than moving up our strength scale. 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
Can I keep a reed diffuser near a window in summer?
Near a window is fine; on the sill is not. What you want is the gentle air exchange a window area sometimes gives you, without the direct sun and the warm glass. Set the bottle back from the opening, on an interior-facing shelf or console, and check the spot at two and four in the afternoon to be sure the sun has not swung onto it.
Is it better to keep a diffuser in an air-conditioned room?
A cooler room does slow evaporation and lengthen the bottle, so an AC room is a good home overall — but keep several feet between the bottle and the vent itself. A direct draught strips the reeds, empties the bottle weeks early and leaves the room smelling of very little. Cool air is the friend; moving air aimed at the reeds is not.
Does heat damage the fragrance oil itself?
Not ours, within normal domestic conditions — the reed range sits on a heat-stable coconut-derived CCT carrier and is tested through 45°C. What heat reliably does is raise the evaporation rate, so the bottle finishes sooner. Formulas built on cheap phthalate solvents are a different matter: they tend to degrade under sustained heat and can turn faintly acrid after several weeks.
Should I buy a 130ml for summer instead?
Only if you want the extra duration, and that is a genuinely good reason — 14–18 weeks against 6–8. It is not a strength upgrade: at the same six reeds a 130ml projects about the same as a 50ml. If summer is emptying your bottles early, fix the placement first, then consider the larger size or an oil refill for the running cost.
How high off the floor should a reed diffuser sit?
Roughly waist to chest height, with clear space around it. Too low and the fragrance never rises into the part of the room people occupy; too high, on top of a wardrobe or a tall shelf, and it sits in the warmest air in the room, which in summer is exactly what you are trying to avoid. A console, sideboard or open shelf near a doorway hits both marks.
Summer placement · 2027
Interior wall, no sun at any hour, clear of the AC — then worry about which bottle
Mountain Breeze from ₹849 and Evening Calm from ₹799 for 50ml (6–8 weeks), ₹1,349 and ₹1,299 for 130ml (14–18 weeks), six fibre reeds in every bottle on a heat-stable phthalate-free CCT base tested through 45°C. Day & Night duo ₹1,498 for 2 × 50ml. Oil-only refills ₹2,399 for 300ml. Free shipping above ₹499, and a portion of every order supports girl-child education through Nanhi Kali.
Shop Mountain Breeze → Evening Calm from ₹799
Continue the read
More on heat, weather and where the bottle stands
- Does hot weather affect reed diffusers? — the two separate effects of heat, explained.
- Do reed diffusers evaporate faster in summer? — and how to plan the year around it.
- How Indian summer affects reed diffusers — why the base matters more than the notes at 45°C.
- 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 where to keep a reed diffuser during hot weather. Product facts — the heat-stable coconut-derived CCT carrier, phthalate-free composition, six fibre reeds and testing through 45°C heat and 85% relative humidity — are verified SOSA product specifications. The hot-season month range quoted (broadly March to June) is general climate framing, not a SOSA measurement, and varies widely by region and year. Surface verdicts, reed-count suggestions and the bottle-life effects described in heat are SOSA working guidance from in-house testing and customer correspondence, not laboratory measurement; results vary with building construction, aspect, floor level and ventilation. 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.