Along with fuchsias, pelargoniums are among the most popular pot plants. However, from the houseplant point of view they are far more important and useful, since they generally enjoy far lessand drier conditions. As well as being very free-flowering, and bearing magnificent blooms with many lovely colours and markings, they often have delightful foliage. Pelargoniums include the well-loved ‘geranium’, the flamboyant show or regal pelargoniums, some charming trailers, miniatures, and a number of species and cultivars with fragrant and decorative foliage. Generally, these all grow quite easily under ordinary home conditions, as well as making excellent conservatory, or garden room plants. However, they are unsuitable for hot, stuffy rooms and they must have a in good light.
Most of these plants can be kept for many years if given frost-free winter conditions, and some will even give a good show of bloom in winter if the temperature can be kept higher. With a winter minimum of about 7-10 deg C (45-50 deg F), most forms will remain evergreen and may. within a couple of years. reach a considerable size if not drastically pruned back. Such large plants, if moderately pruned to maintain a neat shape, can make magnificent specimens. bearing masses of blooms. They need at least 25cm (10in)at this stage and may have to be transferred to a position of greater space, such as a garden room or conservatory, or perhaps a porch. The plants can also be used on a for the summer and autumn.
Sometimes, old plants can also be trained as climbers and grown against the wall of a conservatory. Zonal pelargoniums are sometimes trained as standards, but these are not usually very convenient as room plants. Zonal pelargoniums are the plants popularly called geraniums, an incorrect name leading to confusion with the true geraniums, which are mainly hardy border plants. Zonal pelargoniums are distinguished by their more rounded foliage, often with bold and contrasting zones or bands of chocolate-brown colours.
Themay be single or double, and come in all shades with the exception of blue and yellow. In some cases, the foliage is so excitingly coloured and
patterned that the plants can be grown for that interest alone. The miniatures are also of the zonal group. Generally, the zonals are of mixed
parentage, the most important being P. zonule. There are many named cultivars. and to get some idea of the full range it is wise to obtain a catalogue from a specialist grower.
A cultivar famous for many years was ‘Paul Crampel’. a bright vermilion, but there are now many superior cultivars, the vigour having been improved. Their colours are also often outstanding. For example. ‘Orangesonne’. of more recent introduction, has astonishingly vivid. salmon-orange blooms that seem to fluoresce. The semi-double ‘Irene’ geraniums also have lovely colours, large blooms and a strong and compact habit. The recent introduction ofF, hybridmarks an important progress. This is very easy to germinate under window-sill conditions if sown at a temperature of 18 deg C (65 deg F) in early spring. If the are potted into 13cm (5 in.) they will (lower well from summer to autumn and. with congenial warmth, well into the New Year. There are also numerous strains becoming available, and most grow 30—15cm (1-1 jit) during the first year from , the more compact strains remaining at about 30cm (1ft). Miniature zonals usually grow from l5-30cm (6-12in) in height, remaining neat and compact for a number of years. These can be grown in 10cm (Tin) pots.
Regal or show pelargoniums have more triangular, pale greenwith serrated edges. The flower heads usually have fewer blossoms than the zonals, but the individual flowers are much larger and often colourfully marked or patterned in contrasting colours, flowering is not quite so continuous, the main period being summer, with perhaps more blooms in late autumn. They mostly comprise hybrids involving P. cucuUatum, P. fulgidum, and P. grandi-florum. These can be grown in 13cm (5 in.) pots initially, bul can be grown on in much larger pots to form quite shrubby specimens.
Variegated-leaved geraniums originate from the same sources as the zonal types.-leaved geraniums are mostly derived from P. peltatum, and have plain or zoned ivy-shaped . Their trailing habit makes them ideal for hanging-baskets. for which purpose they are highly prized. They flower freely and have large, showy, single to double blooms in a wide range of colours, from summer to autumn. If it is difficult to have a hanging-basket situated in a bright position, the plants can be put in wall pots, on pedestal stands, or placed on any improvized support designed to allow the room to hang down. Scented-leaved geraniums are a mixed group, also including some species. Although some have a good show of flowers, they are really grown for their delightfully scented foliage. The flowers are usually of no great consequence. The leaves are of great value for making potpourri and may be quite decorative. The following cultivars are all splendid iage plants. ‘Crispum Minor’ (linger bowl geranium, neat habit, citron scented). ‘Crispum Varicgatum’ (silvery variegated foliage, lemon scent). ‘Mabel (Irey’ (serrated foliage, powerful citron-ella scent). ‘Attar of ’ (pale mauve flowers, rose scent). ‘Clorinda’ (large
cerise flowers, eucalyptus-like scent). ‘Fragrans’ (silvery-green foliage, white flowers, pine scent). ‘Variegated Frag-rans’. ‘Citriodorum’ (vivid green orange-lemon scented foliage, mauve flowers), ‘Odoratissimum’ (powerful apple scent). ‘Tomentosum’ (peppermint scent). ‘Prince of Orange’ (orange scent). ‘Endsleigh’ (pepper scent). Cactus-flowered pelargoniums are a small group of the zonal type, with curiously quilled narrow, pointed petals. They are very attractive and deserve to be better known. They are grown as for zonal pelargoniums. General culture. All the pelargoniums described here will grow well in a good. Generally, 13cm (5 in.) pots are a convenient size, but plants saved over several years may UCL\ potting-on into larger pots in spring. Watering can be moderate during the period of growth, from late spring to September, but the rest of the time must be judged according to the temperature. Where it is very cold, little if any water should be given. In warmer conditions. where the plants may be flowering in winter to some extent, enough water should be given to keep the compost just slightly moist.
Zonal geraniums can be flowered in winter, for this purpose, takeearly in the year from established specimens that have been saved from the previous year. Root the at about 16 deg C (61 deg F) and pot on to final 13cm (5 in.) pots. During summer put the pots outdoors in a sunny place, preferably plunging the pots in moist peat, and don’t forget to keep the plants watered. When the is about 10cm (Tin) high. snip off the top and also remove any premature flower buds. In autumn transfer the plants to a sunny window-sill. If a temperature of from 7-K)°l’ (4S-S0°I;) can be maintained there should be plenty of winter blooms. To save plants over winter the temperature should be kept above zero. About 5 deg C (40 deg F) is quite adequate. Never be afraid to cut back the plants. Indeed, this is essential to produce neat sturdy plants with plenty of side growth, and must be done in the case of saved plants. If not. they become tall and straggly, anything but decorative. Gutting back is best done in spring when new growth begins. Plants to be saved in cool conditions over winter can also be cut back in late autumn.