Last summer I planted some stock which I bought from the garden centre
as small plants. It has somehow lasted all through last winter -
without losing any flowers - and is blooming away again as a 1.5ft
tall shrub. However, although it's flowering well, the stalks are
yellowed and it looks a bit sad - not sure if I should have pruned it
or what to do now to make it look more healthy. Any suggestions
please?