Flowering Plants for the Greenhouse



The Norfolk Island pine makes a splendid plant for a cool conservatory and can be kept in a 250mm (10in) pot for a long time. It has a form rather like a Christmas tree. It prefers slight shade and good ventilation. If the plants become too large or leggy, cut them back and use the cuttings for propagating new stock. Water well in summer and sparingly in winter. Keep frost free.


This plant is sometimes known humorously as the cast-iron plant because of its resistance to neglect. When looked after well, it can be quite handsome. The cream variegated form should be especially looked for. The plants do well in slight shade and their appearance can be greatly enhanced by treatment with a leaf-shine product. A minimum temperature of 7 C (45 degrees F) is needed.


There are many extremely beautiful foliage begonias. Most are liable to deteriorate at temperatures below about 10 C (50 degrees F), and they like slight shade and moderate humidity in summer. Begonia rex is a favourite, with exotically marked and coloured leaves often splashed silver. The iron cross begonia (B. masoniana), so named because of the bold cross mark on its leaves, is also most attractive. Many begonias bear flowers as well as striking foliage, but only rarely can the flowers compete in catching the eye, as in B. corallina and B. tiger, for example.


This group of plants belongs to the pineapple family and is found in nature growing in moss or leaf debris, often above ground in tree branches or rocks. This indicates how they should be grown, that is, in a mossy, leafy compost. There are many bromeliads to choose from. A number produce exotic ‘flowers’ which are mostly composed of coloured bracts. The species with the more striking leaves may have the least interesting flowers. Most plants form a rosette of foliage with a central ‘cup’, called an ‘urn’. Keep this topped up with water, otherwise water or spray sparingly from the top of the plant only. Most will survive a minimum temperature of about 10 C (50 degrees F).


This delightful plant is best bought in the form of a large tuber which can be started into growth in spring, in a warm propagator. Large handsome arrow-shaped leaves, veined and marked with various lovely colours, are soon produced. It loves warmth and humidity but is easily grown from tubers. When the foliage fades, let the pots become almost dry. Then store indoors over winter at a minimum temperature of 13 C (55 degrees F).


This is a very popular and adaptable plant. From a clump of arching foliage grow long stems bearing small white flowers followed by tiny plantlets. It makes a fine basket plant for the conservatory, given about 7 C (45 degrees F) minimum temperature in winter.


This is a climber which, in greenhouse conditions, can reach the roof. It has pale green, spear-shaped leaves with toothed edges. Despite the name it needs a winter minimum of about 5 C (41 degrees F). Watch out for aphid attack and red spider to which the plant is prone. Give an 180mm (7in) pot with good drainage. To encourage bushy growth pinch out the stem tips.


Many species make fine foliage plants for the cool conservatory, but they can become very large. The blue gum (Eucalyptus globulus) is popular and is easy to grow from seed. Look out also for the dwarf golden gum (E. exima nana), the silver gum (E. cordata) and the alpine gum (E. archeri). Eucalypts have attractive juvenile leaves, which may be lost on maturity. Fortunately, new plants are usually easy to grow from seed. Many species produce the familiar eucalyptus aroma and will scent the greenhouse during periods of warm weather.


The attractive dwarf evergreen varieties are excellent foliage plants for cold conditions and deserve to be grown more often in conservatories. Especially recommended are Euouymus japonica ‘Variegata’ and ‘Aurea’, and E. fortunei ‘Vegeta’ and ‘Silver Queen’. The variegated foliage looks its best during winter. They are generally slow growers, but ‘Silver Queen’ can grow tall if allowed.


This bigeneric cross between Fatsia and Hedera has characteristics of both and is excellent for chilly places. The best form is ‘Variegata’ which has cream variegated, glossy ivy-like leaves, but needs to be kept frost free. It can be trained as a bush by pruning, or led up supports as a climber. Do not Over-water.


Although this can be raised from seed the cream variegated form cannot. This is a desirable form but is not so hardy and is best kept frost free. Its foliage is a glossier, lighter green.


There are very many ferns from which to choose, and a good selection is readily obtainable. Some recommended species are ribbon fern (Pteris cretica); ladder fern (Nephrolepis exaltata); holly fern (Cyrtomium falcatum), which has an unusual appearance; bird’s nest fern (Asplenium nidus); and Polypodium vulgare in its choice forms. Most of the hardy garden ferns can be grown in pots but it’s preferable to choose evergreen subjects. They usually do well in shaded places and are ideal in north-facing conservatories or under the staging.


The best-known species is the rubber plant (Ficus elastica). This, however, needs a minimum temperature of 10 C (50 degrees F) to remain decorative. Relatively hardy and ideal for chilly conservatories are the mistletoe fig (F. deltoidea), which bears reddish to yellow berries all year round, and the creeping fig (F. pumila) which is a trailer but can also be grown up supports. In both, the foliage is small and dainty.


There are many ivies of variable appearance, leaf form and height size. All are useful for cold shady places. One of the most impressive is Hedera canariensis which has cream and two-tone-green variegation. This species is hardy, but will grow rampantly in warmth. Sudden wide temperature changes may, however, lead to leaf shedding. It will reach roof height if allowed.

MONSTERA DELICIOSA (Swiss cheese plant)

This well-known houseplant has leaves which are perforated when mature and lobed when young. It can grow to well over a man’s height in good conditions and is happy in surprisingly small pots. It sends down long aerial roots to enter the compost and can survive almost freezing temperatures. If kept at above 13 C (55 degrees F), it may produce arum-like flowers and elongate pineapple-like fruits.


There are a number of hardy palms for gardens that can be grown in pots indoors and are ideal for chilly conservatories. For example, Chamaerops humilis and Phoenix canariensis, which is almost hardy. Several are sold as houseplants and grow very well in cool greenhouses or conservatories. The Hozveia palms are especially good, but need 7 C (45 F) winter minimum. Palms seem to grow well in comparatively small pots. Water well in summer and sparingly in winter. Pot-on every two years at the most when young.

PELARGONIUM (Scented geranium)

This group of pelargoniums is noted for leaf fragrance and few have much in the way of showy flowers. They are named according to their scent. For example, nutmeg, lemon, orange, rose bowl, and peppermint. They can be grown much like other pelargoniums, in general, and have the same preferences for light and air. They are most desirable in conservatories, where they often scent the air when conditions are warm. Specialist pelargonium nurseries will have a good selection from which to choose.

PILEA CADIEREI (aluminium plant)

There are a number of pileas, but this species is the most common and is easy to grow. Its attractive silvery foliage suggests its common name. It is neat and bushy in habit and is useful where space is limited. It can suffer from magnesium deficiency, causing leaf distortion and poor growth. Treat by adding a few crystals of Epsom salts from time to time.

SAXIFRAGA STOLONIFERA (mother of thousands)

This well-known pot plant has long runners carrying baby plants which can be detached and rooted. Look out for the superior variety ‘Tricolor’, which has roundish pinkish veined leaves. It is slower growing but very attractive. Keep frost free. It is very useful for wall pots, shelves and similar positions.

SOLEIROUA SOLEIROLII (mind your own business)

So-called because of its creeping invasive habit, this plant is mat forming and therefore very useful for creating ‘carpet’ effects; it will grow over the surface of beds and pots to hide them and produce a natural effect. Do not allow it to dry out at any time. Winter at 5-7 C (41-45 degrees F).

TOLMIEA MENZIESII (pick-a-back plant)

This plant is so called because of the little plant-lets that form around the leaf edges. These can be detached and easily rooted. A creeping plant with prettily marked foliage. It produces spikes of pinky flowers in summer and is useful for shelves, hanging containers, edges of staging and similar positions; ideal for chilly conditions. There is a variegated form but it is not so hardy.


Tradescantia fluminensis, in its various forms, is a popular trailing houseplant. It has pretty markings and colours which develop best if it is given good light and not overwatered. It is frequently confused with Zebrina pendula, which has leaves that are green and silver above, and purplish below. This plant does tolerate shade and will often grow under staging. Keep well pruned and propagate from cuttings.


There is a vast range of these attractive plants, and many can be grown successfully in a mixed greenhouse collection. With few exceptions they need a lot of light and make a good choice for such places as a south-facing conservatory. They can survive without water for quite a time and, therefore, are ideal if you are unable to give regular care. This obviously does not mean that they can be left without water indefinitely. During summer most need plenty of water but they should be left to rest on the dry side in winter. Many produce quite showy flowers. Make your choice from the following selection.

28. August 2013 by admin
Categories: Featured, Garden Management, Top Tips | 3 comments

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