December

General Tasks

  • Continue digging and tidying up of herbaceous beds.
  • Start bringing forced bulbs indoors.
  • Take root cuttings.
  • Cut back late-flowering, chrysanthemums and take cuttings.
  • Take cuttings from perpetual flowering carnations.
  • Check bulbs, corms and tubers in storage.
  • Water over wintering plants in the greenhouse.
  • Remove flowering houseplants to the greenhouse after Christmas.

The Flower Garden in Early Winter

What to do in the flower garden in December

December is the ideal time of year to create new beds, dig over established beds if the weather is reasonable. Tidying of existing herbaceous beds can continue, and all leafy and soft organic material should be added to the compost heap, with any woody or diseased material placed on the bonfire or removed from the garden.

Now is a good time to taking root cuttings from herbaceous perennials while the plants are dormant. This will provide plenty of new plants for re-stocking borders in late spring or early summer. See our section on Propagating Plants from Cuttings for details. Suitable herbaceous plants for root cuttings include:

  • Alkanet (Anchusa azurea)
  • Bear's breeches (Acanthus mollis)
  • Blanket flower (Gaillardia)
  • Hollyhocks (Alcea rosea)
  • Japanese anemones
  • Oriental poppies (Papaver orientale)
  • Perennial mullein (Verbascum phoeniceum)
  • Phlox (Phlox paniculata)
  • Pasque flowers (Pulsatilla)
  • Sea hollies (Eryngium planum)

Once wallflower plants have settled in and are showing signs of growing away, the tops should be pinched out to encourage a bushy appearance and also to restrict the height.

Late flowering chrysanthemums should be cut back after they finish their display. Place the stools under the staging in the greenhouse. Those prepared last month will be sending up shoots, which is ideal material for taking cuttings now.

Take the time to check any bulbs, corms and tubers in storage for any signs of rot or disease. These include dahlia, gladioli, tuberous-rooted begonias and montbretia (Crocosmia). Any rot or diseased areas should be cut back to healthy flesh and the cut treated with a fungicide. Badly rotted bulbs should be discarded.

Over wintering geraniums and fuchsias will need an occasional light watering, to keep them from drying up. Too much water, especially in a cold greenhouse or cold frame, could lead to attack by grey mould.

One herbaceous plant that will shortly be coming into flower is the Christmas rose (Helleborus niger). The flowers are susceptibility to weather damage, so protect the buds and flowers from this by putting a cloche over the clumps or just a sheet of glass resting on bricks or large stones. Either will give them enough shelter. Some alpine plants and several of the choicer winter flowering crocus can also benefit from this protection.

Keep houseplants healthy by providing a temperate, draft free, environment. Centrally heated houses are too hot for many houseplants, especially cineraria, azalea, cyclamen and primulas. Too much heat, dry air, droughts and low light can often cause houseplants to suffer badly and even die. Put flowering plants in a light, airy spot, but remove them afterwards to a cool greenhouse or a cool (16°C (60°F)) airy and light room in the house. Avoid over watering, which is the most common cause of death to houseplants. However, azalea and cyclamen will need a moister atmosphere, which can be provided by frequently misting the plants with water at room temperature, or standing the pots in a pebble filled bowl which contains water up to the base of the pot. As the water evaporates, it creates a moist microclimate for the plant.

Next page >> Taking care of the Lawn in December >>

Plants for December

Plants in flower this month:

helleborus

Helleborus

iris flowers

Iris stylosa

winter flowering pansies

Winter-flowering pansies

For bulbs see

Lawns.