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Grow Your Own Rainforest
Jan Sked
Fortunate indeed are those of us who live within easy access to natural stands of rainforest. To walk within that rainforest, to sit and dream, to feel the peace and tranquillity, and to experience a oneness with nature - surely we all wish for this at some time in our busy commercial lives. With so much of our natural vegetation disappearing at an alarming rate, it is becoming more difficult to find these pockets of paradise.
So, why not try to recreate a little of that rainforest feeling in our own gardens? Even on the smallest suburban block you may achieve that 'feeling' of rainforest with the correct plantings. After all, you can plant 50 rainforest trees in an average suburban back yard if you space them at 2 to 3 metre intervals.
However, there can be a few drawbacks to this type of gardening. For instance, if you have close neighbours, they may feel threatened by your burgeoning greenery and insist on trimming your plants all along the fenceline. If possible, get your neighbours 'on side' before you begin and encourage them to plant in a similar way, so that your gardens become extensions of each other.
Another factor is the work involved in the preparation of a rainforest garden. This could be quite considerable if you wish to create the best possible growing conditions for your plants. Then, too, there are no "instant"' rainforest gardens. It may take several years for a recognisable rainforest to emerge. However, as any real enthusiast will tell you. That is all part of the enjoyment of gardening.
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| "....you can plant 50 rainforest trees in a suburban backyard if you space them at 2 to 3 metres apart." |
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Remember, a rainforest garden is a permanent garden. Its framework is based on its trees and these can be expected to grow 8 to 10 metres in about 6 years; so be very certain that this is what you want before you begin. Removing a quantity of trees of that size could be quite a costly exercise.
The advantages of a rainforest are numerous. Once the initial work has been done and the trees begin to grow taller with their branches intertwining, they form a closed canopy cutting out the light to weeds and grasses that seek to invade the garden. This eliminates the weeding problem and your garden becomes practically maintenance free.
The summer temperatures within the garden become considerably lower, as the plants cool the air by evaporation from their leaves. This, in turn, will make your home that much cooler, particularly if you are able to surround it with your garden. In winter, the effects of the cold, blustery winds are minimised, as your rainforest acts as a screen to protect you from their chill. The severity of frosts is also reduced by trees and, in most cases, entirely eliminated. If you require warmth and sunlight in the winter months, then some deciduous species should be used - Red and White Cedars (Toona ciliata and Melia azedarach), Koda (Ehretia acuminata), Bats Wing Coral (Erythrina vespertillo), Silky Oak (Grevillea robusta) and Flame Tree (Brachychiton acerifolius).
Rainforest plants need not be devoid of floral beauty. The colourful flowers of this pink form of the Blueberry Ash, Elaeocarpus reticulatus , are followed by bright blue berries. Select the thumbnail image or highlighted phrase for a higher resolution image (29k).
In cyclonic areas a rainforest garden can be a great protection. Because the trees are planted closely together, they support each other and there is much less danger of branches or whole trees being blown down. The thickness of the shrubbery will catch and hold flying debris, such as roofing iron and other sharp building materials, thus protecting you and your home from damage.
Now, if you have definitely decided to grow your rainforest, the real work begins.
Site Selection
If you have an acreage block, then you can choose the most suitable spot - perhaps a gully or a southerly or easterly slope. With plenty of space, there is no limit to the size or type of trees you can grow. The only limitations will be the amount of work you are prepared to do and the amount of money you are prepared to spend.
In more confined spaces on a normal suburban block with neighbours in close proximity, you must choose your area and your species carefully. The taller trees of the rainforest should be avoided. Concentrate on the smaller trees, shrubs and groundcovers. Do not plant your trees closer than 5 metres to your house (or your neighbour's). You can then fill the intervening space with understorey plants.
If you have a natural gully or slope, so much the better, but a flat site is quite acceptable if the soil has reasonable drainage. However, a flat site can be given interest and improved drainage by mounding. The use of rocks and logs will hold pockets of soil and prevent organic material from being washed away with heavy rain.
Protection
When plants are small they need protection from strong winds and frost. Some form of windbreak is necessary, mostly on the western to south-eastern sides. This can be provided by existing trees and shrubs, fences, walls, buildings, or anything that creates a barrier. If none is available, a screen of quick-growing shrubby plants should first be grown. Suitable species could be:
Acacia fimbriata (Brisbane wattle), A.aulacocarpa (hickory wattle), A.irrorata (blue skin), A.perangusta (Eprapah wattle), Commersonia bartramia (brown kurrajong), C.fraseri (brush kurrajong), Hibiscus heterophyllus (native rosella), Macaranga tanarius (macaranga), Omalanthus nutans (native poplar), Pavetta australiensis (pavetta), Pittosporum venulosum (rusty laurel), Trema tomentosa (native peach).
Most rainforest plants do not require overhead protection from the sun. They grow so much better in the sunlight, but should be hardened off properly before planting out to avoid sunburn. Do not plant straight from a shady holding area into the open garden.
Soil Preparation and Mulching
Before planting the rainforest, it is recommended that the soil be cultivated, preferably by rotary hoe or similar method, as this gives the plants a better chance to get their roots down and begin growing. however, whether you do this or not, it is important that the ground be free of weeds and grass before planting. This can be accomplished by cultivating, spraying with glyphosate, or by the simple method of covering it all with a thick layer of newspapers or cardboard, which will prevent any growth occurring.
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| "....heavy mulching is very necessary to ensure that soil moisture is retained." |
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The ground should then be heavily mulched. Mulch should be at least 10cm thick. Any organic material may be used, as long as there is plenty of it - grass clippings, leaf litter, straw, seaweed, shrub prunings, sawdust from untreated timber are all suitable. I make a practice of returning all organic material that comes from the garden back into it, and my neighbours are more than happy to donate all their lawn clippings and fallen leaves as well. Not surprisingly, they think I am a bit peculiar, but it does save them the effort of taking it all to the dump! This gives me a sufficient quantity of mulch to keep an increasing colony of earthworms happily engaged day and night in converting it all into beautiful, friable loam.
One of the most important requirements for rainforest plants is to have a cool, moist root system. They appreciate sunlight and can tolerate a little wind, but, if their roots dry out they will die. Therefore, heavy mulching is very necessary to ensure that soil moisture is retained.
Planting
I prefer to plant out trees that have reached a height of 60cm or more in their container. Rainforest trees are generally slow to make root growth; so, the larger the plant, the more roots it will have, and the better it will cope with the open ground. At that size, trees can be planted at almost any time of year, except during very hot or very cold weather.
They may be planted immediately after the ground is mulched. Just part the mulch, scoop out a hole, position the plant and press the soil back firmly around it. Then replace the mulch over the soil and right up against the stem of the plant, so that all soil is covered, This does not harm rainforest species.
The pelleted, slow release fertilisers, like Osmocote or Nutricote, may be sprinkled in the bottom of the hole at planting, using about 30 grams per planting hose. I have also used Agriform slow release tree planting tablets, placing one tablet beside each plant about halfway down the planting hole.
After planting, each plant should be given a good watering to completely drench the soil and bring it into contact with the roots.
Lilli-pillies are popular plants for rainforest (and other) gardens. Most have spectacularly coloured fruits as shown by Syzygium australe. The fruits can be made into jams. Select the thumbnail image or plant name for a higher resolution image (28k).
Photo: Eric Anderson.
Planting Guide
When you begin planting your rainforest, do not try to duplicate Nature's way. The natural cycle of regeneration of a rainforest takes hundreds of years. Instead, plant your tall growing canopy trees first - spacing them 2 to 3 metres apart. Intermix quick growing species with slow and try to use as much variety in plants as possible. Your choice is limited only by the availability of plants, and native plant specialist nurseries and Forestry are now producing quite an extensive range of rainforest species.
My own garden is established on a 30 perch (800 sq. metres) suburban block and I have the following trees growing:
| Acacia bakeri (marblewood) | Acmena ingens (red apple) |
| Acmena smithii (lilly pilly) | Acronychia wilcoxiana (silver aspen) |
| Agathis robusta (Queensland kauri) | Alectryon subcinereus (wild quince) |
| Alectryon reticulatum (alectryon) | Alloxylon flammeum (tree waratah) |
| Aphananthe philippinensis (native elm) | Archidendron grandiflorum (fairy paint brushes) |
| Argyrodendron actinophyllum (booyong) | Argyrodendron trifoliolatum (brown tulip oak) |
| Backhousia anisata (aniseed tree) | Backhousia citriodora (lemon myrtle) |
| Backhousia myrtifolia (carrol) | Baloghia inophylla (scrub bloodwood) |
| Beilschmiedia obtusifolia (blush walnut) | Brachychiton acerifolius (flame tree) |
| Callitris baileyi (Bailey's cypress) | Carallia brachiata (corkwood) |
| Cassine australis (red olive plum) | Castanospermum australe (black bean) |
| Choricarpia subargentea (giant ironwood) | Corynocarpus rupestris (southern corynocarpus) |
| Croton insularis (silver croton) | Cryptocarya obovata (pepperberry tree) |
| Cryptocarya triplinervis (brown laurel) | Cupaniopsis anacardioides (tuckeroo) |
| Cupaniopsis flagelliformis (brown tuckeroo) | Cupaniopsis serrata (smooth tuckeroo) |
| Darlingia darlingiana (brown silky oak) | Davidsonia pruriens (Davidson's plum) |
| Diospyros geminata (native ebony) | Diploglottis bracteata (tamarind) |
| Diploglottis campbellii (small-leafed tamarind) | Diploglottis cunninghamii (native tamarind) |
| Dissiliaria baloghioides (lancewood) | Drypetes australasica (yellow tulip) |
| Ehretia acuminata (koda) | Elaeocarpus grandis (blue quandong) |
| Elaeocarpus reticulatus (blueberry ash) | Elaeocarpus "Prima Donna" |
| Elattostachys xylocarpa (white tamarind) | Endiandra pubens (hairy walnut) |
| Euroschinus falcata (ribbonwood) | Ficus coronata (creek sandpaper fig) |
| Flindersia collina (leopard ash) | Flindersia pimenteliana (rose silkwood) |
| Flindersia xanthoxyla (yellowwood) | Geissois benthamii (red carabeen) |
| Gmelina leichhardtii (white beech) | Grevillea baileyana (white silky oak) |
| Grevillea hilliana (Hill's silky oak) | Grevillea robusta (silky oak) |
| Guilfoylia monostylis (native plum) | Halfordia kendack (saffron heart) |
| Harpullia hillii (blunt-leafed tulip) | Harpullia pendula (tulipwood) |
| Hernandia bivalvis (grease nut) | Hicksbeachia pinnatifolia (monkey nut) |
| Jagera pseudorhus (foam bark tree) | Lepiderema pulchella (fine-leafed tuckeroo) |
| Litsea bindoniana (bollywood) | Macadamia integrifolia (Queensland nut) |
| Mallotus philippensis (red kamala) | Melicope micrococca (white euodia) |
| Metrosideros queenslandicus (golden myrtle) | Neolitsea australiensis (green bolly gum) |
| Neolitsea dealbata (white bolly gum) | Opisthiolepis heterophylla (Findlay's silky oak) |
| Petalostigma triloculare (quinine tree) | Pittosporum rhombifolium (hollywood) |
| Pittosporum venulosum (veiny laurel) | Placospermum coriaceum (rose silky oak) |
| Pleiogynium timorense (Burdekin plum) | Polyalthia nitidissima (canary beech) |
| Polyscias elegans (celerywood) | Rhodamnia argentea (white myrtle) |
| Rhodomyrtus psidioides (native guava) | Rhodosphaera rhodanthema (deep yellowwood) |
| Schefflera versteeghii (hairy umbrella tree) | Sarcopteryx stipata (steelwood) |
| Sloanea australis (maiden's blush) | Stenocarpus sinuatus (wheel of fire tree) |
| Sterculia guadrifida (peanut tree) | Syzygium fibrosum (fibrous satinash) |
| Syzygium forte (white apple) | Syzygium luehmannii (cherry satinash) |
| Syzygium moorei (rose apple) | Syzygium paniculatum (magenta lilly pilly) |
| Syzygium tierneyanum (river cherry) | Syzygium wilsonii ssp. cryptophlebium |
| Toechima tenax (steelwood) | Toona ciliata (red cedar) |
| Xanthostemon chrysanthus (golden penda) | Xanthostemon oppositifolius (white penda) |
As the trees grow taller, they can be underplanted with shrubs, especially around the margins, to keep a leafy screen at the edge of the rainforest. In my garden I have the following understorey plants:
| Acalypha nemorum (southern acalypha) | Alchornea ilicifolia (native holly) |
| Alchornea thozetiana (Thozet's holly) | Alyxia ruscifolia (chain fruit) |
| Argophyllum nullamense (silver leaf) | Austromyrtus fragrantissima (sweet myrtle) |
| Austromyrtus inophloia (thready-barked myrtle) | Brachychiton bidwillii (little kurrajong) |
| Breynia oblongifolia (coffee bush) | Bridelia leichhardtii (small scrub ironbark) |
| Bursaria incana (prickly pine) | Canthium coprosmoides (coast canthium) |
| Carissa ovata (native current) | Citriobatus pauciflorus (orange thorn) |
| Cordyline haageana (pygmy palm lily) | Cordyline manners-suttonii (palm lily) |
| Cordyline petiolaris (broad-leafed palm lily) | Cordyline rubra (red-fruited palm lily) |
| Cordyline stricta (narrow-leafed palm lily) | Cryptocarya laevigata (glossy laurel) |
| Cupaniopsis newmannii (long-leafed tuckeroo) | Cuttsia viburnea (native elderberry) |
| Eugenia reinwardtiana (coastal cherry) | Eupomatia bennettiana (small bolwarra) |
| Eupomatia laurina (bolwarra) | Fagraea berteriana (native gardenia) |
| Graptophyllum excelsum (native fuchsia) | Graptophyllum ilicifolium (Mt. Blackwood holly) |
| Graptophyllum reticulatum (Buderim holly) | Graptophyllum spinigerum (Samford holly) |
| Harpullia alata (winged-leaf tulip) | Hypoestes floribunda (hypoestes) |
| Leea indica (bandicoot berry) | Mallotus claoxyloides (scrub odour bush) |
| Maytenus bilocularis (orangebark) | Medicosma cunninghamii (pinkheart) |
| Monococcus echinophorus (monococcus) | Murraya ovatifoliolata (native murraya) |
| Pavetta australiensis (pavetta) | Phaleria chermsideana (scrub daphne) |
| Phaleria clerodendron (rosy apple) | Phyllanthus lamprophyllus (ferny phyllanthus) |
| Pilidiostigma rhytispermum (plum myrtle) | Pipturus argenteus (native mulberry) |
| Pittosporum revolutum (Brisbane laurel) | Psychotria daphnoides (smooth psychotria) |
| Psychotria loniceroides (hairy psychotria) | Randia benthamiana (native gardenia) |
| Randia chartacea (narrow-leafed gardenia) | Randia fitzalanii (brown gardenia) |
| Rapanea variabilis (muttonwood) | Rhodamnia dumicola (rib-fruited malletwood) |
| Strychnos axillaris (strychnine bush) | Syzygium wilsonii ssp. wilsonii |
| Tabernaemontana pandacaqui (banana bush) | Wilkiea macrophylla (large-leafed wilkiea) |
Once the closed canopy is established, groundcovers and ferns should be added. Alocasia brisbanensis (cunjevoi), Alpinia species (native gingers), Cordyline species (palm lilies), Costus speciosus (spiral ginger), Dianella species (flax lilies), Lomandra species (mat-rushes), Plectranthus species, shy native violets (Viola hederacea) and a good assortment of native ferns, will all lend character to young rainforest garden, especially if they are used amongst logs and rocks edging your pathways.
As the tree trunks reach higher, they can act as hosts for epiphytic ferns and orchids, or as supports for a range of climbing plants. There are quite a variety of native climbers that could be used, including Aristolochia species (birdwing butterfly vines), Cissus species (native grapes), Clematis species, Elaeagnus triflora (Millaa Millaa vine), Faradaya splendida (glory vine), Geitonoplesium cymosum (scrambling lily), Hoya species, Jasminum species (native jasmines), Pandorea species, Passiflora species (native passion fruit), Tecomanthe hillii (Fraser Island climber) and Tetrastigma nitens (shining grape) .
White flowered plants are useful in an urban rainforest because they tend to be more visible than darker flowered species. Faradaya splendida , is vigorous climbing plant with large flowers about 60mm across. Select the thumbnail image or plant name for a higher resolution image (19k).
Photo: Jan Sked.
Pathways
Pathways are most important, so that you may walk within your garden and absorb the true atmosphere of the rainforest. They should be planned in the beginning to meander through the area and avoid the developing plants. Keep them soft with leaf litter and outline them with logs or rocks for a natural effect.
Fertilising
With such a concentration of plants in one area, soil nutrients can be quickly used up. Therefore, if you want your trees to continue to thrive and grow, it is wise to carry out a regular programme of feeding once they have been established for a year or so. I sprinkle sulphate of ammonia and one of the complete fertilisers over the whole area twice a year, preferably in August and February, at the rate of 10kg to 50 square metres. While the trees were still small, I used half this rate.
Watering
Water is very necessary to a rainforest, especially during the developing years. However, although rainforest plants appreciate plenty of moisture, they do not like boggy conditions. They are essentially shallow-rooted plants and therefore require regular watering and regular applications of mulch to conserve moisture.
The ideal watering arrangement is a sprinkler system with mist-type spray nozzles set as high in the canopy as possible to simulate natural rainfall. For some reason, this type of watering seems to benefit the plants more than applying moisture at ground level. And there is nothing more attractive than the sight of moisture glistening on the leaves in a rainforest garden.
Maintenance
Once the rainforest is properly established (in about 5 or 6 years, if growing conditions are good) there is very little maintenance required. Weeds will not grow in the shady conditions provided by the closed canopy. A dressing of fertiliser now and then, the addition of extra organic material (although, after about 8 years, natural leaf and litter drop from the plants should be sufficient to keep the forest floor in a well mulched condition) and watering in dry periods are about all that is needed.
So there you have it, your own piece of paradise. You can sit on a tree stump in your rainforest, contemplating the green serenity about you, listening to the birds in the tree tops above, and feeling sorry for that poor fellow over the road spending his time weeding and mowing in the hot sun.
Jan Sked is the editor of the quarterly Bulletin of the Queensland Region of SGAP. This article is an updated version of one that originally appeared in the December 1982 issue of the Bulletin.
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Australian Plants online - March 1997
The Society for Growing Australian Plants
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