Can no one help? Both plants have developed yellowing on another leaf. So whatever the problem is it's getting worse.

Thanks kindly for your thoughtful reply. I apologise in advance for the wall of words below, there's an update which may be relevant.

I'm using a NPK: 8,2,6 fertilizer, something that's just occurred to me is that it's about 4 years old. The fertilizer that is. Could that have lowered the strength?

UPDATE:

I noticed that both pots the monsteras are housed in have a lot of build up. I repotted the smaller one into a slightly larger plastic (no clay to hand) pot yesterday, the roots were very healthy and strong. There was no root rot of bounding. The larger one, I repotted into the only other pot I had available which is the same size, clay and without build up. Some roots were fragile and broke but there was no obvious sign of rot (black mushy roots). There was a slight smell that I can't put my finger on. Could this be a sign rot was setting in?

The smaller one I throughly watered after reporting with some super thrive. The larger one I've left to adjust, there's some moisture in the medium. I'll water the larger one this morning (I didn't have enough water, I live in a very hard water area that uses high concentrations of fluoride too. So I use water from my dehumidifier to water my plants. I've noticed a difference).

So I guess the questions now are:

is the fertilizer I use good enough, should I purchase something else? If so, does anyone have any specific recommendations? I live in the UK & I've found there's limited selection here.

could the build up on the pot be the cause of their decline? How do I get rid of the build up? I've used bleach, but the discolouration remains.

Does anyone know if the smell from the roots could be a sign that rot has set in? Is there anything that can be done? I've read cinnamon, is this true?

Please feel free to add anything you think I've missed or should/shouldn't be doing. This is a huge learning curve for me. I know not everyone finds growing lovely plants hard, but I do! I would very much like to discover what the root of the problem is for these Monsteras to avoid it in future.

Thanks for reading and helping me.

Seem that the root just fine. Root rot ussually dark, smells bad and soft. If you using npk fertilizer, then it's mostly only suply nitrogen, phosphate, and potash. There are many kind of nutrients that plant need, macro and micro. Try find complete fertilizer, at least 15 kind of nutrients that plant need. For non organic medium, i ussually give liquid hydroponics nutrients. With complete nutrients, new leaves should grow normally.

If the bad smell was swampy and the roots looked fine then it was probably the soil that was turning anaerobic. Good thing you got rid of it.

I really don't know what the cause of the smell is. The roots were a bit fragile, some broke off easily. But there was nothing that I noted that appeared slimy or mushy.

looking for hydroponic nutrients has left me confused! It's very expensive but I can't tell what the difference is between brands or what I should be looking for. I'd always read that they deal well with a general fertilizer. Sorry I really am lost! Thanks for your advice and help!

Just like nil said, the medium maybe turn into anaerobic. Every 4-9 days, root hairs dead and regrow, so even if you're using inert porous medium, if you plant a tropical fast growing species, there will be organic materials in there that reduce soil porosity.

General fertilizer is designed to use on normal soil, which is already rich of minerals and organic materials so micro nutrients usually available enough. If you use inert materials, you should provide all nutrients manually, just like hydroponics that serve complete nutrients, otherwise use normal soil with porosity adjustment.

Art, I haven't looked at this post closely, but if you're looking for the does-everything-suitable-for-all-houseplants fertiliser, get Dynagro FP 9-3-6. That's the NPK ratio but it also has everything else in it so nothing else needed. It was recommended to me on this forum. Good luck :)

Thanks so much! I'll take a look at this one. I really hope this helps them!

An update:

I picked up some foliage pro for them and have used it once in one of the waterings. There was an immediate and noticeable worsening of leaves. They've split more, gone more yellow and black at tips. I've removed the leaves that are completely yellow.

I think there's something else at play here, rot? Leaf disease?

As theres the other plant that I have (https://www.houzz.com/discussions/need-help-identifying-cause-of-sickly-elephant-ear-plant-dsvw-vd~4824767) that seems to also have problems. I'm wondering if I'm dealing with the same for all of them.

Anyone have any suggestions? I don't think these plants will make it through the winter at this stage. Please help, this is just sad.

Back to basics : can you post current photos of them and summarise the situation eg. how long have you had them, when repotted, what into, how you care for them etc. I know you've written some details already but I'm finding it hard to put it all together, maybe my coffee hasn't kicked in...

Overwatering needs to be looked at, although if they're in a perlite/bonsai type medium it should be freedraining and aerated. How are you deciding that it is time to water?

You mention "buildup" - what exactly do you mean? If this is happening since you repotted it is very significant (or do you just mean the pots are stained from previous use?) If there is a buildup of minerals and salts in the soil from fertilisers and/or water this will cause problems such as toxicities and imbalances and also interfere with the roots absorbing water because the salts create an osmotic pull the other way.

I'm suspecting they've been watered too often and/or fertilised too much, so let's look at that first. Using the dehumidifier water is good, drenching them when you do water them is good, giving them lots of light is good. We'll try to work out what else to do depending on your answers. Don't be sad!

Yeah, i know it's frustrating dealing with sick living things that can't talk. At some point sometimes i just give them the best soil i know, give good watering, then leave them alone for 2 weeks. Most of the time they gave me good surprise when i almost give up. It's not an advice btw, just sharing..

Hi robin98(NZ(9b)) thanks for your help!

*I've had the plants for approximately 2 years.
*I repotted them approximately 1-2 months ago.
*Both were in terracotta pots, now just the larger one is. The smaller one is in a plastic pot now, there's been no change in either plant other than getting worse.

*I water both when the top 2 inches are dry, I use my finger or a wood dowel to tell if the soil is damp, mainly my finger. If the top 2 inches are dry I water until soaked, with the water draining freely through the holes. I never let them sit in water for longer than maybe 30mins, after watering.
*The build up was before I repotted, it looks like salt or water hardness. I removed them from those pots and placed them in fresh pots that had been disinfected prior to use. There's some build up since that time on the rim of the terracotta pot (can be seen slightly in photo below of the top of the pot)

I'm still sad, but learning to cope with it! ;) Well, I'm trying to learn from this experience. Thank-you so much!

I've included some newer photos, please feel free to ask more questions if necessary. I'm considering removing the large one from it's pot, to repot again, but into a smaller pot after I remove some roots. It smells from the top of the soil now, and although when I repotted previously there was no indication of rot I'm thinking this is either leaf disease of some type or root rot.

I removed these leaves:

When did they start getting yellow leaves? Before or after you repotted? Were they ever healthy and growing in the last two years? What soil were they in before you repotted? How long ago did you start using dehumidifier water?

Salts and minerals can come from your water source and from your fertiliser. Seeing buildup on the pots means buildup in the soil too. This creates toxicities and imbalances, and interferes with the roots ability to absorb water, resulting in sickly plants with wilting yellowing leaves with brown dead patches. Sounds like this has been a factor, and I'm trying to figure out if it still is an issue to address (by flushing) or is well in the past.

Your watering frequency could be a factor too ie. too often : use the wooden dowel to check the soil moisture right down at the bottom of the pot, not just the top two inches, and don't water until this is fairly dry. Not bone dry, but just so there's only a trace of moisture you can detect - the tip of the dowel won't look wet but will still feel slightly cool.

I would have said that flushing any salt buildup out of the soil and then adjusting your watering habits could be all that is needed, except it sounds like one plant is already rotting - the top of the soil shouldn't smell - so you need to sort that out. A fungicidal soil drench could help unless its too advanced in which case you'll need to unpot it to check the roots.

FoliagePro is a really good fertiliser, I use it on all my houseplants, but hold off using it until your plants have turned around.

I agree with robin. And stop fertilizing for now; roots apparently grow a little better with plain water.

Also, consider getting some reverse osmoses (R/O) water from one of those grocery store water machines and using that to water for a while just to be certain that you're not adding to any soil imbalances that are going on. It generally sells for less than $0.50/gallon, so it's worth a try.

Hi robin98(NZ(9b)) & litterbuggy (z7b, Utah),

Thank you so much for your input and advice. I've taken it all onboard. I do have a couple of questions though. What fungicide should I use? Bearing in mind that I live in the UK, I don't think we have many options here. Would yellow sulfur powder work?

I'm also not familiar with reverse osmoses water here, but I'll do my best to continue to look for some.

To answer your questions (thanks!):

When did they start getting yellow leaves? - a couple of months ago

Before or after you repotted? - before, no noticeable improvement, but noticeable decline

Were they ever healthy and growing in the last two years? - yes, almost the entire time I've had them (approx 2 years).

What soil were they in before you repotted? - the same type of mix

How long ago did you start using dehumidifier water? - approximately 1 year


Gosh, I'm stumped! I watered the larger one (which is the one that has the smell at the top of the soil) when the pot was dry to the touch and the soil felt dry. I did this throughoughly, as a result it did that wonderful guttation. Possibly it was telling me it had too much water.

If you guys can recommend a fungicide safe for indoors, I'll use that and repot in new soil. I hope I don't lose these guys.

Thanks so much!

I'm ignorant of fungicides, so let's hope robin knows more or someone else pipes in.

Do check the moisture at the bottom of these pot. My guess is that it's quite wet.

Bit stumped too - your water should be fine and your soil should be fine too but clearly it's not or you wouldn't have smelly soil and what sounds like root rot.

I'd take it out of the soil and see what's going on with the roots. Remove any rotting ones, rinse the rest off well (& maybe dip in fungicide if you can find one), and repot in new 511 type mix.

Can't advise specific fungicide sorry, maybe someone else can chime in. If you can cut all the affected tissue away it may not be needed anyway.

Also, when watering, you said you don't let them sit in water more than 30 minutes - I wouldn't let them sit in water at all, not for any minutes. Water them at the sink or something so it drains directly out.

BTW, you need to know whether the soil is dry at the bottom of the pot, because it tends to stay wet even when the top few inches of soil are dry. Push a sharpened dowel, disposable chopstick, or wooden skewer through the soil to the bottom of the pot and don't water until the tell comes out feeling dry.

I agree, important to check deep in the bottom of the pot, not just the top couple inches. I also go by the weight of the pot, it's a quick easy check for smaller plants in plastic pots, they're noticeably lighter when dry. Try it in conjunction with using a skewer to help you interpret.