Cultivation of Australian Cycads

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Although the Japanese cycad, Cycas_revoluta, is used widely in landscape projects and is popular in Australian gardens, the horticultural potential of our native cycads has not yet been realized. True, some demand exists for Lepidozamia_peroffskyana and certain species of Macrozamia in landscape work but at present most of the Australian horticultural diversity is in the hands of a relatively small number of private collectors. However, many indigenous cycads make striking features in small or large gardens, and can also be used very effectively in grouped plantings. A few far-sighted nurserymen have been propagating native cycads over the past decade and an increasing range of more advanced material is now becoming available. It is anticipated that there will be an escalation in the use of Australian and exotic cycads both in private gardens and in landscape applications in the future.

Cycads are horticulturally very forgiving plants, requiring a minimum of attention and being undemanding in their soil, water and other environmental needs; in this respect they are ideal for the low-maintenance garden. As with all plants, however, they do respond to careful planting in good-quality soft, periodic applications of a balanced fertilizer during growth phases and to irrigation in times of drought. With only modest attention, cycads, once established in a garden, will produce foliage (and cones) quite abundantly - surprising many gardeners who consider them slow growing plants. Some thought should be given to the placement of feature cycad plants; a common fault is underestimating the ultimate size of the plants and placing specimens too closely to each other or to other plants.

Cycads mix well with other plants; interesting examples are garden blends of cycads and palms, cycads and bromeliads, cycads and succulents (particularly the caudiciforms) and cycads with grass-trees and other natives. Cycad plantings are well complimented and somewhat easier to manage when under-planted with ground-covers such as ornamental grasses, low-growing flowering perennials, etc. Rocks, pebbles and mulches can all be similarly beneficial in showing a cycad planting to its full advantage. Many cycad species make excellent container specimens and are ideal subjects for decorative pots on patios, on verandahs and in courtyards. Most species of Macrozamia, Lepidozamia and Bowenia are suitable for containers and for in-ground plantings. The Australian Cycas species are somewhat more difficult, especially in areas away from their native northern latitudes. On a note of warning - many Cycas and Macrozamia species have sharply-pointed leaflets and strong spines towards the leaf bases and on the cone scales; these are not compatible with small children and pets.

Cycads are also becoming increasingly popular as bonsai subjects. Again, until recently it has been Cycas_revoluta and to some extent the Mexican 'Cardboard Plant', Zamia furfuracea , which have been favoured by the bonsai enthusiasts. However, almost all the native Cycas and Macrozamia species have potential in this respect - particularly the older, perhaps harshly treated or neglected plants and those with branches.

A vital factor in cycad growing is that the plants are sited with good drainage. If necessary, plants should be placed on built-up mounds especially in gardens with clay soil. Reasonable attention should be given to the water supply - cycads are fairly drought tolerant, but long periods of dessication will eventually take their toll. The cycad species from the northern parts of Australia are not generally as cold tolerant as those from the more southern latitudes.

Pest and diseases are relatively untroublesome and can be readily controlled with commercial preparations. Them is some concern that cycad plants introduced from the wild bring with them beetles of the genera Melanotranes and Demyrsus; these are trunk borers and can do considerable damage if left unchecked. It is also the case that larvae of chrysomelid beetles occasionally feed on the foliage of native Cycas species, sometimes resulting in complete defoliation of the plants; this can also occur in garden plantings.

It is a matter of personal choice if one wishes to remove the dead leaves from plants as new growth flushes appear; some enthusiasts prefer to have the 'natural look' of the skirt of dead leaves below the plant's crown, others prefer the neater appearance of a more manicured specimen.

Cycads are easily grown from seed although some patience is required for the first few years. Gardeners with access to male and female plants of the same species are able to produce their own seed crops by artificial pollination, i.e. by dusting the pollen from the male cones into a receptive female cone of the same species. The seeds take some months to develop and even after harvesting usually need a few more months as a 'resting period', during which the embryo slowly increases in size, before being put into the warm and humid conditions that lead to germination. Propagation from suckers or offsets is a somewhat faster process and is similar in technique to rooting cuttings from shrubs. An application of sulphur dust or a tree-wound treatment preparation helps to minimize the chance of rot.

Additional information on cycad cultivation, propagation and management can be obtained through the various cycad societies (see Links). On a cautionary note, it must be pointed out that strict federal and state legislation has been put in place to protect our flora in national parks, state forests and on private land. We strongly advise cycad enthusiasts against removing plants from the wild under any circumstances. Fortunately, the increasing supply of nursery-propagated plants makes it relatively easy at present to obtain a diversity of native cycads at modest prices.

Contributed by:

Ken Hill and Roy Osborne from Cycads of Australia