When it comes to time off from work, if I am not away on holiday, there's nothing more satisfying than a bit of houseplant maintenance/allotment work/gardening to keep me out of trouble.
Today the weather can only be described as "filthy", so allotmenteering/gardening is out: instead I decided to repot a 3ft tall Dracaena marginata that had become seriously pot bound. I forgot to mention this problem in my houseplant care notes below, but if a houseplant of yours is looking really sad (wilting or yellowing leaves, not growing at all, looking dull or lifeless) and you've tried everything else, it could be that it's potbound. Of course, there are plants that actually like being potbound: just check your houseplant book to see if this is the case for the plant you're dealing with. If it is, you probably shouldn't repot it.
Potbound means exactly what you might think. The plant's roots - which naturally want to spread out in search of water and nutrients - will eventually become crammed into the confines of the pot, and the plant will start to suffer.
The picture to the right is the dracaena's roots prior to repotting - it was seriously potbound but it was such a tough cookie that it was only just starting to show the signs. The answer is to repot into a container about 5-10% bigger than the current pot, adding new compost (I recommend peat-free houseplant compost).
Make sure you tease out some of the compacted roots so they can spread into the new compost, and water well straight after planting. I'd also recommend covering the surface of the compost will small pebbles or gravel - not only does it look attractive, but it also reduces the risk of mould growing on the soil, which can be an irritant to asthmatics.