Beware of waterlogged rosemary at this time of year, especially if it’s growing in pots or somewhere that doesn’t have great drainage. Too much water can lead to leaves turning brown and then it won’t be long before your poor rosemary plant ends up looking a bit twiggy and, um, dead.
It happens quite quickly, and although it is fairly dry at the moment, it only takes a few heavy rainfalls for the damage to be done. At this time of year it takes the soil a lot longer to dry out again so your rosemary plant may be sitting in soaking wet soil for a few days after it has rained.
There’s not much you can do to save it once the leaves start to turn brown, so prevention is key. If you’re growing your rosemary in pots, bring them in under cover somewhere, or if you can’t do that try to pop them on an old pallet or something so that they can drain more easily. If they’re growing outside, try to make sure they are unlikely to get too wet and waterlogged. This isn’t necessarily easy, but doing a few things like making sure that puddles are unlikely to form around it or cunningly surrounding the base with plastic to prevent the water getting through will help if you think it is likely to become waterlogged.