OmAndScop said:
Initially I was paranoid about overwatering so maybe let it dry out too much. Since then I've been fastidiously waiting for the top of the soil to dry out before watering it again - I checked on it today and the top of the soil is still moist about ten days after I last watered it.
I'm not an expert but I think this may be the main issue. That sounds a little too long, and is a sign that either the soil mix doesn't drain very well or the pot is too big, and can cause root rot. Pot size looks fine, so I suggest replacing most of the soil with something better. A good general mix is 25% perlite, 35% crushed bark or coco husk chips, and 45% compost or peat or potting soil. You can find a lot of different recipes with different ratios online. If you don't want to disturb the roots too much, you could also repot to a terracotta pot using the soil it's in now and it will dry out quicker also.
OmAndScop said:
I'm in Glasgow, Scotland, so fairly far north (it's pretty dark this time of year) and the plant sits near a north-facing window - all the advice online was to avoid direct sunlight but maybe a complete lack of it, in such extreme latitude, isn't helping?
While it should do ok in low light, this looks like it may be a little too low. The advice to avoid direct sunlight is in my opinion not the best advice. My Monstera thrives with several hours of direct morning sun on the leaves. Evening sun would be great, too. If you introduce it to a brighter spot gradually, even some direct midday sun may be ok up in Glasgow. More sunlight will also mean more evapotranspiration and the soil should dry out quicker.
