Sick Monsterosa

[MitchCA]

We have a large - floor to ceiling, mature – over 50 years old, monstera deliciosa which has been in its current location in a corner with windows on two sides and a ceiling lantern above, so lots of light and out of any draughts for just over a year. Prior to that it was in a similar location in another house.

In the last couple of weeks the underside of the tops of some of the leaves and some of the leaf ribs are going dark brown. The leaves are not drying out as it is in a pot with a built in reservoir which is regularly topped up, from March to October it is topped up with a liquid plant food, just water at other times. This regime has worked well.

Any suggestions as to what it might be and how to remedy it would be appreciated.

Thanks.

 

[Meadowlark]

Welcome @MitchCA . We have some really knowledgeable members here on your monstera deliciosa...I'm not one...but hopefully they will be along shortly.

 

[oneeye]

Where are the leaves thats bronzing, top or bottom of the plant? Is it Winter there?

 

[cpp gardener]

It may just be adjustments to the new location. If it's almost the same as the old one, the changes are slight and take longer to show than if it is a drastic change from Noth window to South window; or reverse. The first 2 pictures look like mild sunburn or possibly, as oneeye suggests, chilling. Have the 'window-exposed' leaves shifted sides of the windows? Rotated from East to West?

 

[MitchCA]

Where are the leaves thats bronzing, top or bottom of the plant? Is it Winter there?

We're in the UK just going into winter.
Bronzing describes it well. It's the tops of many leaves and some ribs that are affected, mostly towards the top of the plant.

 

[MitchCA]

It may just be adjustments to the new location. If it's almost the same as the old one, the changes are slight and take longer to show than if it is a drastic change from Noth window to South window; or reverse. The first 2 pictures look like mild sunburn or possibly, as oneeye suggests, chilling. Have the 'window-exposed' leaves shifted sides of the windows? Rotated from East to West?

It has changed from N to S, are they that sensitive?
Could be chilling if they susceptible to it as it is now nearer to bifold doors, which we had open quite a bit during summer. However I would have thought the effects of this would have shown up sooner.

Some of the affected leaves are very close to the ceiling so wouldn't get any direct sun so sunburn sounds unlikely.

 

[oneeye]

Your Monstera deliciosa is going into a slower growth stage and doesn't need any kind of fertilizer. If you overfeed the plant, the top leaves will bronze because excess salts from the fertilizer accumulate in the soil, which disrupts water uptake and damages the leaf tissue. In other words excess salts in the soil will impair the plant's ability to regulate water movement which can lead to reduced transpiration. You may stop the bronzing by doing a gentle water flush with pH-neutral water on watering day.

 

[cpp gardener]

Yes, they can be that sensitive especially if they were in the other location for a long time. Like if you always use SPF 50 and change to 45. It doesn't happen that fast with plants, usually, but after a bit it starts to show. Note the extant and intensity of the change and watch for any increase or change in size. It might just stay the same and eventually grow new leaves that hide the marks. Unless you move again!

 

[oneeye]

A common mistake I have seen often is when plants start to have problems, the grower will add fertilizer. Since the problem above is caused from high salt, adding fertilizer would make it worse. The best way to find out how much salt has accumulated in the substrate is to do a pour-through and catch the leachate and test the liquid with an EC or TDS meter.