Sowing and planting
Hardy annuals can be sown in pots or modules to provide colour in the garden. In mild areas you can sow directly outside. Marking out irregularly shaped seedbeds and broadcasting drifts of different seed gives a more natural look.
Sweet peas can be sown outside this month. Place autumn-sown sweet peas in a sunny position, perhaps on a high shelf in the greenhouse that gets plenty of light. Sow summer bedding plants in a heated propagator or under glass.
Early spring is an ideal time to plant herbaceous perennials, including Geranium, Astrantia and Oriental poppies.
Plant summer-flowering bulbs. Prepare the soil first, to ensure that drainage is sufficient to prevent the bulbs rotting. Anemone coronaria tubers need particularly well-drained soils.
Plan a continuous crop of cut flowers for this summer. Perennials such as delphiniums and annuals can be grown to produce a useful and beautiful display.
When space becomes available in the greenhouse, pot up cuttings of tender perennials taken last summer and at the beginning of this year. Bulk up plant numbers by taking more cuttings from the largest of the new plants.
Indoor forced bulbs that were in the house for winter displays, but which have now finished flowering, can now be planted into the garden, taking care not to disturb the roots.
Cutting back, pruning and dividing
Cut back ornamental grasses and other perennials left for winter interest, if you have not already done so. Even if they still look good, you need to make way for the new growth.
Cut off old leaves of hellebores that produce flowers from ground level (including Helleborus x hybridus and H. niger - left) to expose the flowers and remove possible foliar diseases such as hellebore leaf spot.
Divide and/or plant bulbs-in-the-green, such as snowdrops (Galanthus) and winter aconites (Eranthis hyemalis), if not done last month.
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.
Divide hostas before they come into leaf.
Divide hellebores and polyanthus-type primulas after flowering.
Propagation
Propagate more dahlias from tubers. Pot them up in multi-purpose compost so that the old stalk is just above the surface. Water and place in a warm, light position or in a propagator. Once the fresh shoots have grown to 7.5-10cm (3-4in), cut them off carefully with a knife. Dust the ends with hormone rooting power and push them into a pot containing cuttings compost. Place back in a propagator or plastic bag until roots appear.
Perennials that are showing new shots from the crown can be propagated via basal stem cuttings. Shoots 7.5-10cm (3-4in) high are cut from the parent plant with a sharp knife. Sometimes a piece of root can be taken with the cutting (which speeds establishment), but stems can be cut without root, and then dipped in hormone rooting powder before striking into growing medium, as for softwood cuttings.
General maintenance
Continue to deadhead winter-flowering pansies and other winter bedding. Pansies will carry on into the spring and even to early summer, if attended to frequently.
Deadhead the flowers of Narcissus (daffodils) as they fade, but allow the foliage to die down naturally.
Herbaceous perennials infested with couch grass and other perennial weeds should be lifted so the roots of the weeds can be removed. Improve the soil by digging in organic matter before replanting.
Clear up weedy beds before mulching. Lighter soils can be mulched now, but heavier soils are best left until March, when the soil is warmer. Mulching with a deep layer of organic matter helps to condition the soil, suppress weed growth, insulate plant roots from temperature fluctuations, and conserve soil moisture during the summer.
Bulbs coming up in the rock garden or in containers may benefit from overhead protection from the rain. A sheet of glass or perspex placed on piles of bricks will do the job.
Top dress spring-flowering alpines with grit or gravel to show off the plants and to help prevent stem rots. Mulch may need replacing after weed removal.
Improve the drainage of heavy soils by working in lots of organic matter.
Perennials putting on plenty of growth may need support by the end of the month.
Check whether containers need watering. Even at this time of year, they can dry out. Pots that are sheltered by eaves or balconies can miss out on any rainfall. If in doubt, check the compost at a hand’s depth to see if it feels dry. Aim to keep pots moist, not wet, and don’t let them dry out.
Pots and tubs benefit from topping up with fresh John Innes compost. Old compost can be removed and replaced with new if there is not much room for topping up. Some grit will also deter slugs.
Feed borders with a general-purpose fertiliser at the manufacturer's recommended rate.
It is best to get supports in early, so that the plants grow up through them, covering them discreetly. Adding rigid supports afterwards usually looks unattractive and results in bunched stems lacking sufficient ventilation. Criss-crossing strings from hidden or decorative posts work well, allowing stems to grow up in the gaps between strings.
In mild areas, you should remove winter coverings of fleece, straw, polythene etc, to prevent new shoots being damaged. In cold areas, you are best waiting until the risk of frost has passed.
Planning ahead
Members can order seed from the RHS Seed Scheme between 1 November and 31 March.
You may wish to get your sweet pea wigwam growing supports ready. In mild areas, you can transplant young plants to the feet of the wigwam, using a light twine to tie them in.
Pest and disease watch
Continue to protect new growth on lilies, delphiniums, hostas and any other plants affected, from slugs and snails.
Check autumn-sown sweet peas growing in cold frames, and keep watch for mouse and slug damage.
Hellebore leaf spot can be a problem on old foliage of hellebores. Cutting back the old leaves should control the problem.
Aphids can multiply rapidly during mild spells. Remove early infestations by hand to prevent the problem getting out of hand. Protect sweet pea plants in particular, as they can get sweet pea viruses, which are transmitted by aphids and other sap-sucking insects.
Watch out for downy mildew and black leaf spot on winter pansies. Remove any infected leaves and destroy badly affected plants.
Look out for rots (such as crown rot, Sclerotinia, delphinum black blotch, black root rot and antirrhinum rust).
Remove dead leaves from around the basal rosettes of alpine plants to prevent rotting.
Top dress spring-flowering alpines with grit or gravel to show off the plants and help prevent rotting around the neck.
