Mark - can you tell what soil they in, how often do you water them, do you feed them with fertilizer? Thanks

Too cold. They've slowed down. They'll pick up again when it goes over 26°C even at night. Or you can put them on the radiator. Or a heat mat.

WOW...eeyore your plants exploded and grew tall! Mine six month plants are much smaller but quiet fat which I like. Very interesting how they grow differently.

Mark, as mentioned above, what is the soil mix they're in please, it looks very fine and compact? That could be causing some issues with their roots. Watering info also required. Also the one on the right looks as though it could have spider mite problems? Have you inspected both plants for fine webbing and tiny cream coloured insects, mainly unde the leaves? They can stunt growth to a standstill as they weaken the plant as they suck its sap. If they were mine I would unpot and check each plants root system. Post a pic if you can. They ideally need a small pot each with some grittier, airier mix, half potting mix for c/s and half perlite would be a minimum requirement. Don't know what available in your immediate area.

They would have slowed down/stopped growing in Autumn as both you and I have such short growing seasons with little sun and low light at this time of year so I wouldn't expect to see much growth till spring really kicks in, say at the end of March or later for us, sadly.

My plants hardly ever get to see 29 degrees, never ever at night, and rarely in the daytime too, so they live in my sunniest window 365/ year catching what rays they can. A heat pad or radiator would help them along as suggested, but you need to watch the soil mix doesn't dry out too quickly if you try that method. No ferts would have been needed since growth stopped last autumn, but you could start with a diluted amount once they show signs of perking up.

My 7 month old seedlings are also pretty small at around 3 inches tall or 7-sh cm. Like you, mine cooled down for winter and went pretty dormant. I also wasn't watering them enough. But now it's getting warmer and the days longer, they are really busting out with new leaves and fattened up.

Thanks for all the comments!

Can I keep them in the greenhouse in summer?