Sowings can be made in a propagator, in a heated greenhouse or on a windowsill at a temperature of approximately 21°C (70°F) of many summer bedding plants, such as geranium, petunia, impatiens (busy lizzie) and nicotiana along with some perennials. Take care not to sow too thickly or over-water as this can lead to the seedlings damping off (small patches of them suddenly dying for no apparent reason.)
Clumps of perennials can be divided with the healthy young outer portions being replanted into freshly prepared soil - this should only be carried out in milder areas of the country.
Towards the end of the month start begonia tubers into growth, in trays of compost at a temperature of 15°C (60°F). Previously grown tubers with any dead foliage still remaining should be cleaned off and then the tubers repotted in fresh compost. Water them in and a temperature of about 16°C (60°F) should be kept. It's also a good time to plant new tubers of begonias and gloxinias.
You can now begin to sow seeds of cabbage (summer/autumn maturing), celery, parsley, sweet and cayenne pepper, tomato, leek and onion.
Outdoors (under cloches or in a cold frame) you can sow early varieties of carrot, such as Amsterdam Forcing, broad bean, such as The Sutton, and parsnip. Shallots can also be planted out from the middle of the month.