For those who would like to grow rosemary in pots, we have a key piece of advice which is to make sure the drainage is really good so that the compost/soil never gets waterlogged. Rosemary does best in mediterranean conditions really, and you want to try and mimic this by making sure the soil doesn’t get too wet and drains easily.
The best thing to do, is to start each rosemary plant in its own container, measuring about 20cm diameter. You can plant them with the bio-degradable fibre pots (pictured) – the roots will simply push through the fibre. Make sure your containers have several drainage holes at the bottom, or one big hole, and add a layer of crocks – about 4-5cm thick of old broken pieces of pots or stones – as this will help water to drain from the bottom. Fill with compost, and if you can, mix in some grit as well. A couple of handfuls will be enough. Then plant the rosemary plants.
It is always worth standing the pots on a surface that can further help drainage – for example, gravel is better than sitting on a patio slab, because the water can drain away more easily, and we really wouldn’t advise sitting the pot in a tray of water – that would soon lead to waterlogging!
The 20cm pot should be big enough for the first year, then in the second year you can re-pot into a bigger pot, repeating the process detailed above. It’s a good way to keep the compost in check and to make sure your plants always have good drainage. In the third year, move up to a bigger pot again, and then the rosemary should last another 2-3 years before getting overly leggy and woody.
You’ll know quite quickly if rosemary gets too waterlogged as the spiny leaves will turn yellow and brown, as if they have been scorched. If there is any sign of this starting, you should try and dry out the soil as quickly as possible before the whole plant goes.