If you haven’t already done it, this month is the last chance for pruning shrubs and roses, dividing perennials, sowing tender plants and mulching fruit trees.  Also divide and or plant bulbs in the green, such as snowdrops and winter aconites, if not done last month.  
Plant summer-flowering bulbs.  Divide clumps of herbaceous perennials that you want to propagate, those that have become too large for their allotted space and those that are flowering poorly or have lost their shape.
Cut off the old flower heads from hydrangeas that have been left on for protection.  The last of the roses should be pruned by now.  Old fashioned roses and types that flower only once should not be pruned now.  They should be pruned lightly in summer, immediately after they have flowered.  Spray them against black spot as soon as the leaves have begun to emerge.
Plant out lily of the valley crowns also gladiolus.  Plant new perennials including primulas, pansies and violas, watering them well in.  Sow sweet peas outdoors if the weather is favourable and plant out autumn sown sweet peas
Seed sowing should now be in full swing to raise the summer's bedding plants and tender vegetable crops, such as peppers, cucumbers and aubergines.  Most of the bedding plants that need early sowing, such as busy lizzies, lobelias and petunias, require extra heat to encourage speedy germination,
Cover the soil with a generous layer of compost, manure, mushroom compost or bark.  Leave feeding until next month if the weather is still very cold, as any new growth will be damaged by frost.   
It is now the final time to plant shrubs and fruit trees before next autumn.  Prune shrubs such as Buddleia davidii that flowered on last year’s stems cutting them back to one or two buds.  Clip over autumn and early winter heathers with shears to remove old flowers.  Prune out old wood from winter jasmine.  Cut out any winter-damaged or diseased shoots on evergreens.
Plant strawberries in well prepared soil.  Mulch around raspberry canes with compost or manure.  Raspberry canes planted this season should now be cut back to about eight inches from the soil.  If gooseberry bushes have not been pruned do this now cutting back leaders by a third and prune side shoots to two buds. Pollinate outdoor peaches, nectarines and apricots and spray them to control peach leaf curl.  Mulch fruit trees with well rotted manure or garden compost.
Sow tomatoes, cucumbers, melons, aubergines and peppers to grow in the greenhouse.  Sow broad beans, broccoli, Brussels sprouts, carrots, cauliflowers, leeks, lettuces, onions, parsnips, peas, radishes, spinach, and turnips outdoors if weather permits.   If the ground is too wet and difficult to work leave it for a few days until it has dried enough to be handled.   Plant early potatoes, rhubarb, shallots and onion sets and autumn sown cauliflowers.