North facing window says it all. It's freezing. I'm willing to bet that window is drafty and the cold air is killing the spath. Also, being in a colder spot than the others, I'd say it's also overwatered. I don't see a tray under that pot. Does it have a drainage hole in the bottom?

First, NEVER fertilize a sick plant. It can't handle the extra nutrients and the fertilizer alone can kill it.

Second, don't fertilize houseplants in the winter. They need a break. I stop fertilizing mine in October and start again in March.

Here's what I would do:

Take it out of the pot and check for root rot. Remove as many dead roots as possible.

If root rot is the problem, cut the leaves back by half. By that, I mean either remove half the leaves (starting at the bottom) or cut each leaf except the very top one back to 1/2 its length. I know, it will be ugly, but we're trying to save the plant. Spaths grow quickly during the growing season, so it will be o.k.

Put the roots of the plant into a glass of 16 ozs of water with 1 tbsp of Hydrogen Peroxide for 24 hours. This will kill the root rot fungus and also get some oxygen to the plant.

Clean the inside of the pot out with bleach and allow it to dry completely

After this, if you have rooting hormone, dust a little onto the roots of the plant. Repot the plant in fresh potting soil, water well and let the water drain (don't let it sit in water) and put it in a warmer place. Since spaths can grow in near darkness, anywhere at least 3 feet away from a south or west window. East and North windows are too cold.

Use the finger gauge to decide when to water. Stick your index finger down into the soil to the depth of your second knuckle. If it's dry all the way down, water. If not, don't. Simple, foolproof. You can do this for all of your plants.

Hi, thanks for your answer.

Yes, you're right I do have window that is opened during the day and sometimes during the night but it's very large and it's on the side of the window that doesn't open. It could be drafty, I agree.

Maybe I wasn't clear enough - I fertilized it some months ago when it was perfectly normal.

The pot does have drainage holes, it is also in a pot with stones at the bottom for better drainage, so I'm sure it's not rotten. And it's not really moist, now I checked it's on drier side. I already practice the finger method for watering and I have been growing spaths for years. The others are also facing north and are perfectly fine. That's what's puzzling me.

What is interesting that it was growing on the north faced window for years without a problem. I just relocated it for maybe 1 metre.

What about the yellow leaf?

The window location is not the problem....nothing is freezing in the OP's location :-) This plant can probably be grown outdoors there without too much concern.

But I would agree at first glance that this is a watering issue or a water retention issue. I would be interested to know what sort of potting soil you are using and agree with the suggestion to skip any type of regimented watering schedule. Rather, water only as needed by using a wooden dowel or chopstick inserted alongside the rootball to the full depth of the container. If it comes out damp with soil clinging to it, wait to water until the dowel reads as completely dry.

Hi, gardengal48 (PNW Z8/9), thanks.

It is an ordinary garden soil the one you buy in the supermarket. Will check the roots and get back with a photo.

Maybe I should just water it with a diluted peroxide solution next time when watering?

So, the roots were fine, healthy, the soil was not wet. It seemed a little shallow planted when I took it out - maybe it was 4 cm in the pot, the rest were stones.

The pot diameter is 10,5 cm and it is 7 cm deep. There were stones at the bottom quarter. Is it maybe outgrown? It wasn't potbound, however.

The soil is comercial potting soil. The plant is a youngster from my other spaths I've been growig for years and I potted them up.

Sorry, I didn't notice your zone. It should be o.k. with the open windows, because my giant spath is outside with temps getting down to the 40s and it's fine. I just toss a blanket over it if it gets colder. I had one in 9b that died back every winter and came back every spring. Sounds like you know how to take care of them. Put a squirt of dishwashing liquid into your watering water. It acts as a surfactant and helps the water "stick" to the soil instead of just running through as it would in a really dry plant.

The yellow leaf is normal. Mine loses leaves all the time. It's how they grow. You can cut that off. The other leaves look healthy, maybe just thirsty. Maybe, if you have room, put it into the bathroom for a few days so it can get some extra humidity.

Could definitely use a size larger pot. I use Miracle Gro mix with my spath, and it's fine. They like humusy soil.

dirtygardener -- Z9a, N. Central Florida it's not usual yellow leaf you get in spaths. It's not drying, the texture is like that of the green ones, just lemon yellow colour with green patches. The edges remain green, too. It looks like some trace nutrients are needed.

Never use rocks or gravel or other material at the bottom of the pot - just potting soil. They do not help wth drainage at all and just serve to elevate the perched water table.

Not overly comfortable with metric equivalents but the pot seems overly small and shallow to me :-)

It's artificial stones. It usually does good in my experience. Will repot.

No, artificial or not, stones don't help, sorry, pls remove them, Just add 50% Perlite to your mix & that should be fine, some bark would be excellent.

I currently have 4 Spaths, none get yellowing leaves (just sometimes brown edges). I finally have the watering right for these guys & they do well. My current mix is approx 1/3 each C&S mix, Perlite & Reptibark (from the Pet Store), I keep them all on pebble trays to provide some ambient moisture.

The particular stones you're using (mine are called Leca stones) which I use to grow some Hydro sets ups, holds the water into that arrangement & is not helping your plant, it's impeding it fully drying out enough to actually get some air down into those roots, ultimately likely to to suffocate the roots & the plant if left like that, sorry.

it is not getting/absorbing enough water.

your fertilizer is weak , but how often you've been using it? spathe is an aroid and aroids need to be flushed once a month with plain water as they are sensitive to salt (fertilizer) accumulation. changing soil will fix that, but you'll need to flush in the future.

the pot is too small 10cm = 4", 7cm=3" and some of this volume is occupied by leca ? so it's been growing for sev years in 2" of soil? and you let it dry out fully before you water? spathes should never be allowed to dry out fully (that's when they wilt and leaves droop). do it half a dozen times and it will decline. you should replace the soil , repot it in a pot 5cm larger overall (15cm=6") and add perlite to the potting mix like at least a third.

you can rinse the existing leca stones : pour a couple of liters of boiling water thru them to sterilize them, then just cover them with boiling water and add some peroxide to it just in case: like 1tb per liter(quart) and let them soak for 30min in it, drain. then you can add them to soilless mix instead of perlite.

I disagree that you can't use leca stones in the bottom of the pot - they absorb and hold extra water, roots just go around and thru them. they are used in hydro culture and in passive hydro when the plant in a soil mix but is grown over water.

I use scoria instead in the bottom of my pots that I keep outside for all moisture loving plants, as they need all moisture they can get in the heat of summer.

and don't water more then once a day. so scoria helps. and I then bring some of those pots inside for overwintering. scoria remains of course.

when I repot I see very healthy roots usually all attached to scoria.

Lechuza system uses leca in the bottom of the pot - the roots grow thru it and into water reservoir underneath: it's a self-watering system. it is perfect for spathes , as they can always get as much as they need.

African violet mix with addition of some perlite is very suitable for this plant. it loves lots of water. the warmer you keep it , the more water it will need (above 75F at all times is best).

just wanted to add that my Spathes seem to sulk for 3-6 months after repot and not grow much. I usually tent them in plastic for 1-2 months after repot as I noticed on the first repot that the leaves were drooping - they seem to do it every time unless I tent them. With tenting and high humidity they usually perk up after several days. But growing is another matter: it takes awhile for them to recover.

so this time when I repotted in early fall last year I put them on a heating pad and tented them too, as I needed them 'to take' before dark times came.

as I put them in transparent pots I could see the root growth started after 1 month and the first new leaf was showing too. So heating pad helped to speed up the root growth.

I've been growing my S. "Domino' for many years and after some time the base of crowns starts elongating and the crown is above the soil level.

about a year later it starts loosing it's vigor as new off-shoots around it are growing. it is still ok but clearly is 'over the hill'. It is time for a bare-root and 'make-over' - the older trunks will decline so it's best to separate them (I chucked mine after 1 month of repot as they were clearly declining fast).

and I planted the newer offshoots together. they'll stay in that pot for probably 3 years.