Clumber Gardener: Bulbs bring colour and scent to the winter greenhouse

Clumber Park head gardener Chris Margrave.
Clumber Park head gardener Chris Margrave.

For many of us, heating a greenhouse over the winter is too expensive to consider, so most stand empty and unused between a tidy up at the end of the growing season in October and a spring clean in March.

However, it is possible to produce some early colour without heat and hardy bulbs are ideal for this.

Under glass, flowers are protected from the worst of the weather, the fuller petalled double flowered forms can be appreciated at close quarters on greenhouse staging and those varieties with the most delicate of scents can be enjoyed.

There is still time, just, early in the month to plant bulbs and, as we’re nearing the end of the bulb selling season, you may be able to pick up some bargains.

Commercial glasshouse growers know the importance of good light levels during the winter and this applies to the small greenhouse as well.

The glass should be cleaned now to get rid of any grime, moss and algae.

Soapy water or an appropriate disinfectant can be used on the benching and the glazing bars, and the floor swept and any weeds removed.

The bulbs can be grown in pots or pans in a suitable compost or bulb fibre. Give the pots a clean too.

The big three – tulips, narcissi and hyacinths – provide an enormous range of suitable varieties.

There are many double flowered tulips but for an early display in the unheated greenhouse, the double early group is best.

They have large peony-like blooms in a wide range of colours, from brilliant bright reds such as Abba to delicate pastels like the two-tone pink Foxtrot.

Monte Flame is especially striking, combing a bright yellow base with a red-orange flame pattern.

For double vermillion-red blooms go for Holland Baby and Red Riding Hood Double, which also has attractively mottled foliage.

Most of the hyacinths we grow at Clumber are single flowered.

There are a few double flowered varieties which have beautiful ruffled petals.

These are perfectly hardy and have the same powerful scent as their single flowered cousins.

Hollyhock is a deep pink, while Rosette is pale pink.

There is also scent amongst the narcissi and daffodils.

A personal favourite is Thalia, also known as the orchid-flowered narcissus, which has a pleasing scent and produces two, three, sometimes even four white flowers on each stem.

Most narcissi belonging to the jonquilla group have a delicate perfume and blooms in white, cream or yellows.

The yellows, Double Campernella and Golden Echo, are especially fragrant.

Even in winter it is important to ventilate the greenhouse, especially on warmer sunny days.

This will keep the air moving, help dry off excessive condensation and work towards keeping rotting diseases like botrytis, under control.

Cool conditions will also lengthen the display and the flowering time of the bulbs.

Potted bulbs can also be brought into a cool room or kitchen when they have begun flowering and treated as a house plant.

A sunny window is ideal and live plants will last much longer than cut flowers.

Even though we are now into November, there is still time to plant bulbs at the beginning of the month.

Containers for winter and spring interest can also be planted up.

Use variegated evergreens, such as ivy and euonymus, bulbs and spring bedding plants such as polyanthus primroses, pansies and violas.

Protect vulnerable over-wintering plants before the first hard frosts.

Use sacking or straw to cover crowns of plants and bubble film to place around pots.

Lift and bring inside any tender perennial plants such as cannas, gladioli, chocolate cosmos and dahlias.

Prepare ground for new plantings on heavy soils by digging the soil and adding organic matter such as well rotted manure or leaf mould.

Leave ground rough dug to allow frosts to break down the clods.

Prune back taller growing shoots on shrub roses and lavateras.

This lessens the effect of wind rocking the plant and producing a hole against the crown of the plant at soil level.

Leave final pruning until late winter or early spring.