One of the great advantages of a greenhouse is the wealth of plants which it allows to be grown – even an unheated one, opening up a range of possibilities that would be otherwise difficult to cultivate in the British climate. For many, the chance to enjoy exotic looking decorative plants is one of the principal attractions of growing under glass and with careful selection of varieties; the feel of the tropics can be achieved in any greenhouse or conservatory.
Plants for the Heated Greenhouse
The range of exotic decorative plants available to heated greenhouses is extraordinary. Bromeliads are perhaps some of the most arresting, with their striking spiky foliage and showy flowers. Billbergia nutans, for example, is one of the most frequently grown species and although is almost fully-hardy, only within the heated greenhouse will the drooping yellow, red and blue flowers develop. Cultivating this plant with its toothed, thirty-inch leaves requires free watering and the centre of the plant where the rosette of leaves meet should be kept filled with water and by contrast, the compost itself need not be watered until it is nearly bone dry.
A related species, Billbergia fasciata is another worthwhile bromeliad to grow as a decorative greenhouse plant, needing very similar treatment and having silver-mottled leaves and rosy bracts in August. Other suitable plants include Gloriosa, a distinctive climbing plant with reddy-orange flowers and handsomely curved petals in the summer, the highly scented Gardenia, which flowers throughout spring, summer and autumn and the attractively variegated foliage of Peperomia. However, for all-year round display, the stunning large leaves of Dieffenbachia would be hard to beat, while winter-flowering begonias, dracaenas, poinsettias and cyclamen can all be grown at temperatures around 10 – 16 degrees C (50 – 60 degrees F).
There is no reason why the owners of cool greenhouses should be denied the fun of raising exotic-looking plants – there are plenty of candidates which fit the bill very well. Hedychiums are high on the list for bringing a touch of the tropics into cooler climes, their spidery-looking flowers and a heady perfume makes them a perfect choice for a striking, decorative display. A number of species are available, including H. chrysoleucum, H. coccineum , H. densiflorum and H. flavescens, all of which grow well and flower readily. The easiest way to propagate them is by division, lifting and cleaning their rhizomes in early spring. Alternatively they can be grown from seed, which will benefit from a soak in warm water to improve their germination. Sown in late spring or early summer, they should germinate in around four to six weeks.
Other plants which can provide strikingly decorative displays in the cool greenhouse include Gloxinia, with its red, white or purple velvety blooms and interesting foliage, the ever-popular Camellias and the orange-flowered evergreen climber, Streptosolen. However, if you really fancy something a little different and unusual, commonly known as either the “Voodoo Lily” or “Monarch of the East”, Sauromatum venosum is certainly worth a look. Able to grow and flower from its corm without either soil or water, its main claim to fame is the dreadful aroma it gives off when in flower. Although a native of tropical and sub-tropical regions of the world, it will happily flower each year in the cool greenhouse, making it a serious candidate for a bit of shelf space, if only for its novelty value.
However warm or cool your greenhouse, there are more than enough decorative plants to make the growing experience worthwhile and all that is required to make it happen is selecting the right species. Whether the aim is to produce a tropical or Mediterranean look-alike, or simply to have a range of interesting foliage and flowers to please the eye, there are plenty of contenders to chose from – and sufficient variety of shape, colour and form to please anyone, whatever their personal taste.