Growing Decorative plants in a greenhouse

Can you give me a brief guide to growing pelargoniums?

Named varieties of all the popular pelargoniums are best bought from a specialist nursery in early spring in the form of rooted cuttings. From then on you can propagate from plants you have overwintered in the greenhouse; cuttings can be taken either during late summer or spring . The recently introduced ¥I hybrid geraniums (Pelargonium) are very easy to grow from seed sown in late February. Fine-flowering plants will then be obtained by June, with quality and colours equal to, or even better than, the named types. Generally, the plants like good light conditions and ventilation, need to be kept frost-free and must be kept on the dry side in winter, with moderate watering in summer. Do not allow plants to become straggly: cut them back severely if necessary; they will probably be of better shape and flower more profusely. Do this pruning early in the year, just before the plants start into new growth.

Can you recommend some other easy-to-grow greenhouse pot plants?

Few of the most popular pot plants are difficult to grow in the average home greenhouse, given reasonable care. The exceptions are mainly those plants that are artificially dwarfed or brought into flower out of season, such as some chrysanthemums, poinsettias, kalanchoes, and Rhododendron simsii (the so-called Indian azalea). Many greenhouse annuals and biennials are extremely easy to grow from seed; subjects like schizantus, salpiglossis, Phlox dmmmondii (a good pot plant as well as a bedder), busy lizzie (Impatiens), the wishbone flower (Torenia foumieri), and the cigar flower (Cuphea ignea) are several that will give colour a few months after sowing.

Have you any hints on growing fuchsias?

These are best bought as rooted cuttings. It is not very practical to raise them from seed unless you are an enthusiast: the named types are usually far superior. Fuchsias can be grown in numerous ways—brush, trailing, standard, and fancy shapes—but some varieties are more suited for a particular growing habit. Fuchsias that are being trained should not be allowed to suffer chill in winter, as this may cause the top growth to die back. Propagation is easy from suitable stem cuttings taken in spring. The plants like good light conditions, but need slight protection from bright sun with white shading during summer to prevent scorch. Stopping the plants encourages more generous flowering, but they should be left untouched from about eight weeks before the time the flowers are required to give the best show.

What bulbs are specially suited to the greenhouse?

By ‘bulbs’ people usually include all storage organs, such as corms, tubers, and the like. For the greenhouse these fall into two categories: the hardy types autumn-planted for spring display, and the tender kinds started from late winter to spring for summer to autumn colour. The latter include achimenes, begonia, canna, cyclamen, eucharis, eucomis, freesia, gloriosa, gloxinia (Sinningia speciosa), haemanthus, hippeastrum (the so-called amaryllis), hymenocallis, nerine, tuberose (Polianthes tuberosa), smithiantha, Jacobean lily (Sprekelia formosissima), Scarborough lily (Vallota speciosa)—all of which are quite easy to grow given normal cultural attention.

Can I raise my own houseplants in the greenhouse?

Numerous permanent houseplants can be cheaply and easily raised from seed sown in spring. They include Begonia rex, the so-called asparagus ferns (not true ferns), the polka-dot plant (Hypoestes), Schefflera species, the cabbage palm (Cordyline terminalis), various Eucalyptus species, the well loved African violet (Saintpaulia)—grown from F1 hybrid seed, which is easy to manage—and a vast range of cacti and other succulents. Many houseplants are also easily propagated from cuttings, either stem or leaf , if you can get material from friends who have plants you like.

I would like to try growing some exotic greenhouse plants. Can you suggest a few that are not too difficult?

One of the most highly prized greenhouse plants is the bird-of-paradise flower (Strelitzia reginae), with flowers like an exotic bird’s head. This can be grown well in barely frost-free conditions in winter—although it is often described as a ‘stove’ plant! The new hibiscus Fi hybrids, such as ‘Southern Belle’, have immense flowers like dinner plates, yet they are extremely easy to grow from seed, flowering in a few months. The butterfly flower (Schizanthus), in the form of modern hybrids, calceolaria, and salpiglossis all have extremely exotic flower form and colouring, and are also easy to grow.

Bulbs also provide a source of some flowers amazing for size and form; notable examples include hippeastrum and the related sprekelia, gloxina (Sinningia speciosa), nerine, foxglove-like smithiantha, and hymenocallis. There are some very showy shrubby subjects too, like callistemons, with their crimson ‘bottle-brush’ flowers; Erythrina crista-galli, with large wax-textured red flowers; and tibouchina, with its blooms resembling giant pansies.

What are the best permanent foliage plants for the greenhouse?

Palms immediately spring to mind—but there are few suitable hardy types. Remember to select only those that will thrive in the minimum temperature of your greenhouse: you would do well to seek advice from a specialised palm nursery. For the home greenhouse look for foliage that gives an impression of warmth, but is in fact fairly cold-resistant; Fatsia japonica, with large glossy palmlike leaves, is a typical example. Many ferns, too, are cold resistant, but not all may retain their fronds in winter. Hoya camosa is an exotic-looking climber with some good leaf variegation, and it also bears flowers. Among those grown from seed are the popular shrubs Greuillea robusta and Jacaranda mimosaefolia; both have very graceful, ferny leaves but they may eventually outgrow the space available.

Is there any way in which I can adapt my cool greenhouse to grow warmth-loving exotics without running up prohibitive fuel bills?

Provided you select modest-sized plants you can grow these plants in large warmed frames that have been brought into the greenhouse; alternatively, you can partition off a section of the greenhouse to reduce the amount of space that has to be given the extra heat; for frames or cases, electric soil-warming cables are the most convenient means of heating. Some plants to consider include cattleya orchids, and evergreens such as marantas, calatheas, aglaonemas, Cissus discolor, codiaeums, anthuriums, saintpaulias, dieffenbachias, and fittonias.

What special conditions, if any, do I need to provide for cacti and other succulents?

Maximum light is important for most species, although there are a few exceptions such as the forest cacti. Frost-free conditions are important for most too, although there are some hardy species. It is wrong to assume that this type of plant can go without water indefinitely (no plant can); they are, however, well equipped to withstand short periods of neglect and so they are ideal plants for those who have to be away from home and the greenhouse from time to time. During active growth the plants can be well watered, but in winter they should be given hardly any or even left dry. With proper care many plants flower beautifully and become extremely showy. A free-draining compost is essential; most modern potting types will be satisfactory if you add extra grit to them.

How are greenhouse chrysanthemums grown?

There are many types including the ‘cascade’ and ‘charm’ kinds, with masses of small daisy flowers, as well as those used for cutting with giant ‘football’ blooms. In all cases the training is vital to success and can be rather involved, although it is not difficult. The most popular large-flowered types with incurved or reflexed petals should be bought as rooted cuttings in spring and grown on in large pots outside the greenhouse during summer. They must be stopped and a limited number of shoots that then form are allowed to produce buds. The shoots are subsequently disbudded to permit only one bloom to develop on each.

I like the idea of growing carnations all the year round. Can you tell me how it’s done?

For this purpose grow the PF (perpetual-flowering) type. They are bought as rooted cuttings of named varieties in early spring, and the plants will flower from summer onwards in 175 mm (7 in) pots. To get the best blooms in winter, give the plants a bright position and do not let the temperature fall below 10°C (50°F) except for short periods. The young plants must be stopped —the supplying nursery will often do this before despatch—and the stems that develop must be disbudded to allow only one large flower to develop on each.

Can you suggest some other flowers I might grow for cutting?

Try the Christmas rose (Helleborus niger), which needs only weather protection: stocks (Matthioh) of the ‘column’ type and snapdragons (Antirrhinum) grown as single spikes; many other annuals sown in autumn, grown on for early flowering, and chosen for long, strong stems. The various hybrids and varieties of Gerbera are highly prized for flower-arranging; and so too are the various types of gladioli; suitable rose varieties (grown in pots for early flowers), and most of the long-stemmed spring-flowering hardy bulbs, are other good examples.

I have a small greenhouse but I would like, if possible, to try my hand at climbing plants. Are there any that might be suitable?

Many climbers can be rampant and take up lots of room, but they can usually be managed if they are grown in containers which confine the roots. Some good plants to grow in this way are the passion flowers (Passiflora), Abutilon megapotamicum, Chilean bell-flower (Lapageria rosea), Hoya camosa, Stephanotis floribunda (which needs warmth), Plumbago capensis (as a wall shrub), Bougainuillea (as a wall shrub), and Jasminum polyanthum —all widely available. There are also some pretty climbers to grow as annuals such as black-eyed Susan (Thunbergia alata), morning glory (Ipomoea), Chilean glory flower (Eccremocarpus scaber), Maurandia barclaiana, glory lilies (Gloriosa), which are grown from tubers that can be saved, and the balloon vine (Cardiospermum halicacabum).

I have heard that, with various adjustments, my greenhouse would be suitable for growing alpines. Could you tell me what would be involved?

Very many alpine or rock plants are relatively hardy, but they resent wet and humid conditions in winter, and are often better if given just a little frost protection. Their dainty flowers will also look better if they are given some protection from the damaging effects of the weather. An ‘alpine house’ is designed to provide plenty of air, light, and protection, and to bring the plants nearer the eye on extra-high staging. Most alpines are spring flowering and can be kept in frames during the rest of the year if preferred. This allows the alpine house to be used for many ordinary summer- to autumn-flowering plants.

Is orchid-growing beyond the scope of the average greenhouse gardener?

Not at all: few orchids are really difficult to grow, and if you can provide the correct temperature and conditions they are extremely rewarding. The best for the beginner and the home greenhouse are the Cymbidium species, most of which need temperatures of only 5-7°C (40-45°F) in winter and about 16°C (61°F) in summer. There is also no need for a special greenhouse. A catalogue from a specialist nursery will give useful hints for growing and information regarding the special compost required.

Which among my greenhouse plants are most suitable for use in hanging baskets?

Trailing varieties of fuchsia and the ivy-leaved pelargoniums are great favourites; Pendula type of tuberous-rooted begonias are also beautiful. Modern trailing lobelias can be grown from seed and are now very showy; they come in a wide range of colours, and are useful for mixing with other subjects. The bell-flower (Campanula isophylla), columneas, some achimenes, Aeschynanthus speciosus, Hypocyrta glabra, petunias, schlumbergeras, Lachenalia bulbifera, Lobelia tenuoir, and some of the annual climbers (which will also trail) are also popular.

Sorry, comments are closed for this post.