Well the ones in the lounge are.
It’s a west-facing 2nd floor room which doesn’t get massive amounts of light and is kept pretty warm, especially when I’m in the flat.
They don’t get overwatered and the soil’s always slightly damp so I don’t think they’re underwatered either.

And they’re all drying out, going brown and gradually dying.

There is one which is ok, which I bought from a garden centre. The dying ones all came from Ikea, could that be anything to do with it? Any tips gratefully received as it will save me spending £30+ replacing them when they’ve finally gone to meet their maker…

the answer is never simple, what were you expecting. It is easy to overwater a cactus and easy to underwater a venus fly trap.

A citrus might object to Alkaline water, a rubber plant if it gets cold.

West facing may be the problem, but it might not be, the soil being damp all the time might be the problem but it might not, get the picture?

If the leaves are turning brown I always thought that is a sign of overwatering.
Have they got drainage; a hole in the pot or pebbles in the bottom if not.

Do you use a gas fire in that room? I’ve found a lot of plants don’t like that.

Could be that atmosphere is too dry, that’d explain the browning of the leaves. Plants shouldn’t need much water at all at this time of year, most are resting and no plant food unless they are flowering.

I have one plant in our house. It’s an orchid apparently, someone bought it for the mrs. Apparently every one else kills them, ours is a marvel that Attenborough should be filming. I did nothing other than stick it in the window and water it nown again. Hth

Have you fed them?

Whats the PH value of your water?

Are they in soil?

Do the leafs curl up?

Do they claw down?

Are the brown marks more like spots?

Are they rusty coloured

Are the edges of the leaf a different colour ( yellow maybe )

How humid is the room?

Have you googled each plant to see if they require more then just water?

Dumb question, I’ve fallen foul of this myself, but are you sure they are perennials and not annuals? I had a chili and in its first winter it croaked, it depressed me and convinced me that I was brown fingered, until my knowledgable mates pointed out that it was an annual and no amount of love and care would keep it alive..

annuals