There is still time to sow seed of certain biennials to flower next year: forget-me-nots, Iceland poppies, sweet Williams and so on. But nothing makes an impact on the spring garden like wallflowers, with their warm-toned, soft, floppy flowers that exude the sweetest of perfumes. Traditionally they are sown in the open ground - although I'm trying them in deep trays - they'll be easier to protect from this year's rampaging slugs.
If you start them in a spare part of the vegetable patch, don't grow them where cabbages or other brassicas have grown recently, as they belong to the same family, Cruciferae, and may be affected by residual diseases in the soil. Sow sparsely in drills, and when they come up, thin out to a couple of inches apart. In September or even October (but not in cold areas), plant them in their final positions.