Permaculture Designers Manual
CHAPTER 10 –
THE HUMID TROPICS IN PERMACULTURE
Section 10.6 –
The Tropical Home Garden in Permaculture
The wet season is the “hungry gap“, where plants are growing, but too young to harvest.
Early in this season the soil is soft enough to plant and establish trees, but plants must be well-timed as the dry season is long-lasting. Planting too late is to risk drought before ripening of the crop.
Vegetable crop is started at either end of the wet season. Water storages (Module 7 – Water) are essential, no matter how modest, for garden, tree crop and diversity in yield.
Moulds, mildews and root fungi are encouraged by humidity and it is best to use resistant plant varieties or root-stocks.
Mango, papaya, sapote, banana, limes, coconut, cashew, macadamia nut, breadfruit, and mound planted avocado and pineapple, durian, etc… are the garden and orchard framework, as are any productive palm crops.
Large legumes such as Inga, Gliricidia, Leucaena, Cajanus and so on are essential interplants.
In the vegetable garden, yam and sweet potato yield better than, or in place of, potato.
Adapted small-fruits and tomatoes of wilt-resistant strains grow well.
Amaranth is a good green and grain crop. Lima, velvet and Dolichos beans trellis on tree legumes.
Forage and ground legumes provide green mulch and help suppress grasses, as do comfrey and lemongrass.
Chiles, peppers and the range of tropical vegetables are preferred to temperate species.
Bamboos, balsa, teak, palms and mahogany provide structural and craft materials, rattans can be encouraged along waterways and in mangrove edges.
Oil palm, jelly palm, Bactras, Maurantia, salak palm and doum palm provide trusses of useful fruits.
Large insect pests (locust, cicadas. sucking bugs) are plentiful; guinea-fowl or chickens on range are some defense.
Native rodents and pigs can be damaging, and pythons rather than foxes take poultry.
Termites and ants largely replace worms in soil-building and buildings must be constructed to resist them. Geckoes in houses eat many insect pests, as do wolf spiders.
Pigeons and bees and most easily protected from predators by elevation on pole structures or over shallow ponds.
Guinea fowl, francolin, pheasant, and bantams provide essential foraging and insect control services.
The guinea-pig aids small tree establishment as they “chip” the base of young grasses and small pigs of Taiwan strains provide orchard-fruit garden scavenging duties.
Waterfowl and aquatic species add yields to water storages and assist in grass control.
Can be limited by raising large earth banks, selecting valley garden sites, screening plantings with bamboo groves, establishing a general tree canopy through garden and plantation or a combination of these strategies.
Oversize swales aid wet-season water run-off control and diversion to storage. (Figure 10.20)
There is a wide range of specialist crop potential, from rubber (Hevea), betelnut, chalmougra oil and chide to essential oils and medicinal.
Many are suited to primary processing in remote locations, or conversion to commercial quality end products. The high value of processed products enables smallholders or cooperatives to pool research and processing facilities and to select high-yielding varieties.
As well as the essential legumes, a scatter of Banksia, Casuarina, Gigasprema calaspora, and Pultenea with their mycelia associates will fix phosphate and return it via leaf mould.
Several plants “pump” sugars or carbohydrates into soils, while leaf-sucking insects and scale insect’s exude sugars from stems.
Dilute molasses or cane and sorghum sugar juices and stems also activate soil fauna.
Marigolds, neem tree leaves or berries and pyrethrum daisy control soil pests and provide insecticides or water insect control.
The neem tree is often planted to overhang ponds, so that the berries that drop control water-flies and mosquitoes.
Established tough grasses of the savannahs resist gardens and need to be mulched or over shaded with tree canopies.
To mound or raise garden beds for good drainage in the wet season;
To use mulch and mulch-tree species to create topsoil for gardens;
Where logs exist, they make ideal garden bed edges to hold mulch and soil.
Gardens have been devised for many tropical areas, usually containing the following:
Designed for full nutrition for an average family;
Water conservation and safe water disposal (hygiene) a necessity;
Species chosen to suit local cultural preferences;
Sufficiently varied to survive reasonable climatic change, or seasonal irregularity;
Protein sources, livestock; their forages, or grain/legume replacements for meats;
Water routes and use;
Basic foods or staples;
Fresh vegetable and fruit for vitamins, minerals, varied uses;
Some fuels, medicine and flowers.
The elements in Figure 10.23 are those that make up the house structure itself and those that make up the garden, hedgerow, livestock and path access structures.
The best way to use this section is to read it through very carefully, study the plans and diagrams and then improve it or better it to fit to a specific site.
Room size and number is adjusted to family size, but is basically a simple, easily-heated and cooled structure, preferably on slab or raised pise floor, and preferably edge-insulated.
The induced cross-ventilation acts to cool and heat as per Figure 10.16.
In addition, vertical sashes or shutters to each room help to scoop air in.
In hot periods, the main living area is outside rear, or under a similar porch trellis to the front if the people prefer to be seen from the road (as is the case in most close knit societies).
Materials can be local, as can any insulation. Glass is needed, as are some pipes or drains of stone and a tank.
How the Garden Works (Figure 10.20) (also see Figure 10.23)
First, it accepts all water and wastes of use. Only plastic and glass or metal are not used, although some cans may be buried for slow zinc and iron release.
Second, it provides most mulch and a lot of fodder or forage, which when bulked out by house scraps should feed rabbits, guinea pigs, a few chickens and even fatten a small pig.
Next, it is very accessible and well-designed on a need to visit and tend basis.
It is also very natural in appearance and function.
If no septic tank is present, a dry toilet will do and the manure can be put under trees (in pits).
Even “toilet paper” can be built into the hedges (E) (Nicotiana is great, as is Leucaena).
Hot water for showers can be achieved by a hot-water collector or at least a coil of black pipe on a roof or bare area.
With a couple of oil lamps or a photovoltaic array, a solar oven on castors, an efficient cooker and a small solar food drier, life should be fairly cheap and healthy.
Adventure can be sought in teaching neighbors how to do it, writing novels or joining an adventure camp group or even a permaculture group (they behave very diversely!)
See Figure 10.24 and Figure 10.25 for additional details and ideas.
In Taiwan and the Philippines, small intensively planted home gardens are planned to feed a family of five all year.
I have added to these designs my own Permaculture “least-path” layouts to give a very concise and effective model of sustenance garden design for tropical and subtropical regions.
These can also be adapted to temperate regions, using suitable species.
The overall pattern can be altered to fit almost every site form, but is presented here as a flat site pattern.
Although the building of such a garden is fast and simple, its design is sophisticated.
The whole design owes much to the work of the East-West Institute in Hawaii and the Samaka gardens of the Philippines, but the layout is “Purely Permaculture“.
I have named it “Gangamma’s Mandala” after one of our Karnataka (India) Permaculture Design graduates.
Steps in the process are:
1. At the centre of a 100 square meter (1075 square foot) or larger area, describe a circle 2m (6 feet) across and excavate the topsoil (or subsoil) to a dish shape, ridged on the perimeter and about 0.6-1m (2-3 feet) deep from hollow to rim.
This is the banana/sweet potato/papaya circle garden, as per Figure 10.26.1.
The whole circle is then covered with wet paper or wet cardboard, banana leaves or any mulch material and the hollow is filled (or over-filled as a dome) with rough mulch of short logs, coarse twigs, hay, rice husks and sawdust or indeed any humus-creating materials.
A little scatter of manure, ash, lime, dolomite or fertilizer can be added.
If stones are available, bank them to the outside of the rim.
The rim is then planted to 4-5 papaya (a tall variety), 4 or so bananas (dwarf types) and 8-10 sweet potatoes.
If available, yams or taro can be placed inside the rim. Later, beans can be planted to climb the papaya and banana stalks.
In the banana circle, we can place a grid or platform of wood over the mulch, and this then becomes an outside shower or wash-up area.
2. A circular sunken path 0.6m-1m (2-3 feet) wide is covered with sawdust or gravel around this central circle garden and off it, “keyholes” or indentations are made.
The system now looks like Figure 10.26.2.
3. Around each keyhole a bed 1.5m-2m (5-6 feet) wide is first edge-banked with soil 100cm-200cm (4-8 inches) high to prevent water run-off and the beds are then papered and mulched (as for the banana circle).
The whole garden now looks like Figure 10.26.3 in plan. The thick lines represent low earth ridges.
Thus, we have six major keyhole beds, each of which is separated from the next by a thin strip of lemongrass (Cymbopogon citratus) or Vetiver grass ( Vetiveria zizanioides).
Just outside the periphery ridge, strips of lemongrass, comfrey and arrowroot (Canna edulis) form a kikuyu grass barrier and behind that, a taller border of cassava /banana/papaya /pigeon pea/Leucaena/ Crotolaria forms a hedge or windbreak.
All these borders give mulch, forage, barrier effects or food.
The whole mandala is fenced or has a spiny woven hedge boundary for cattle exclusion, if necessary.
The mandala has now been earth-shaped and mulched to prevent water run-off and to conserve moisture.
We now proceed to plant, using buckets of good soil to place the following zones of plants:
A. On the track edge border of the central path and keyholes, within stoop-reach of the path, plant those frequently-plucked or everyday greens of high value.
Here, the placement and selection criterion is that all the plant or most of it is picked for much of the year.
These are the PATHSIDE GREENS; they include all the chive and shallot species, plenty of parsley, coriander, thyme and sage, celery, broccoli, edible chrysanthemum, chard and any such long-bearing or perennial greens (e.g. various perennial spinaches).
This is therefore a narrow border to the inner side of the keyhole beds, planted in the ridge soils there.
B. Behind or outside the path side plants, we plant a 1m (3 foot) wide strip of species which are frequently picked over a short to long season, e.g. tomatoes, eggplants, bell peppers and chilies, bush or staked beans and peas, kale, corn, okra and so on.
These are the NARROW BED plants, all within reach of a path or keyhole. As yet, we do not need to step on any beds to harvest.
C. Just out of reach, on the outer borders of the keyhole beds, we place most long-term root crop (potatoes, sweet potatoes, carrots) or any crop we CUT AND REMOVE (cauliflower, head lettuce and cabbage).
Thus, for this crop we step (once) on the bed to harvest and replant, following root crop with fava beans or dahl (dried beans or lentils).
All beds are replanted as they are harvested and a top mulch of straw, sawdust, bark, dry manure or chips is added annually.
Rabbits, guinea-pigs, chickens or small livestock are fed from weeds, waste vegetables, household scraps and forage greens from the border hedge (comfrey, cassava, Leucaena or lemongrass).
Vetiver grass, lemongrass etc. are cut 3-5 times annually for mulch. The roots of Vetiver grass prevent rodent burrowing from outside the system, as do the root masses of Euphorbia species.
All trees, shrubs and tubers are planted before papering and mulching, and then about 30cm (1 foot) of troddn-down and wetted mulch is added.
Tray seedlings 8-10 cm (3-4 inches) high and large seeds such as peas or beans are each planted in a hole burrowed in this mulch, with a good double handful of soil to each hole.
Small seeds (lettuce, carrot) are scattered thickly on lenses of soil 50cm (1.5 feet) across and 5-8cm (2-3 inches) thick, placed and firmed on top of the trodden mulch, followed by dusting of a 1cm (1/2 inch) thick layer of fine soil.
All seed can be presoaked. The whole bed needs a good soak with a sprinkler at each stage.
If no weed seeds are included in the mulch, the beds are weed-free. It takes 9-15 months to build up worms and a good soil.
Any surplus compostable material can be pushed under the top mulch layer.
A larger system, designed for a community kitchen at a rural center in Karnataka state (India), uses a core assembly of 4-5 banana circles and has 8-12 keyhole beds. In this case, a keyhole accesses the banana circles. (Figure 10.26.4)
Any one of these banana circles can contain a small pond for frogs and water convolvulus, or taro.
We can plant a Leucaena or palms for high shade and mulch, at the junctions of the keyhole beds. The hedge surround eventually provides the annual mulch (Figure 10.26.5).
This garden is intensively-planted, has very little path per bed area, is easy to build and maintain, provides everyday greens, minerals, vitamins, allows no water run-off and can be built on any substrate (rock, concrete, roof areas).
We have here combined basic nutrition, soil building, rainwater harvest, eventual self-mulching, various weed and animal barriers, small livestock fodder, overhead shade, non-dig gardening, “least-path” access, direct waste water disposal and a pleasing design.
The system described here is adapted from Ray Wijewardene, 1981, Conservation Farming, IITA-Sri Lanka Program, Dharmapala Mawatha, Colombo 7, Sri Lanka.
It is a deliberate fuel wood/mulch/soil improvement crop integration of great use in the tropics but adaptable to any climate, with good species selection. (Figure 10.27)
The essentials are simple enough:
- Correct spacing to shade the ground fully but to allow cropping between the tree legumes;
- Lopping to leave stems 0.5m-1.0m above ground (a suitable tree legume is tagasaste or Leucaena);
- Sowing of crop just before rain or irrigation, to beat the growth of weeds;
- Possible two-crop sequence, with mulch also returned from crop wastes.
A very similar system is used in Africa with Gliricidia and more recently in New Zealand with tagasaste as the green crop.
A parallel system (regular or irregular in ground plan) is successful in establishing small trees, which otherwise perish from frost or in open grass competition.
At least two problems arise in sustained coppicing of legume trees.
Firstly, such coppice should be confined to warm wet periods, allowing mature leaf to carry over into dry, cool or frosty periods.
Secondly, constant coppice weakens trees over 5-8 years and replanting is necessary.
Very few legume trees will sustain constant coppicing and other strategies are called for.
Perennial thin-crowned leguminous trees can be spaced throughout the orchard and garden or fast-growing and short-lived legumes can be allowed to grow and die or can be ring-barked or felled on a 2-5 year cycle.
However, with permanent high legume cover, mulch can be obtained all year from a variety or non-legume hedge and understory.
Such species as Nicotiana, Echium fastuosum, Lantana, cinnamon, even clumps of daisies, wild ginger, lemongrass, Vetiver grass, Pennisetum and crop wastes from maize, Sesbania and soft ground legumes or comfrey provide constant mulch under high legume cover, so that the coppicing of susceptible legumes themselves is reduced or eliminated.
In any evolved system, avenue cropping or mulch provision can be sustained by a carefully planned system of mixed non-coppiced tall legumes giving a seasonal leaf drop (Erythrina, Tipuana tipu) and a row series of non-legumes for ground mulch.
There are several reasons to erect barriers of plant species:
- As a block around the annual garden to resist invasive grasses (such as kikuyu and buffalo grass, knotweeds etc);
- As a corral for animals or to keep grazing animals out of a compound or to guide animals to a gate or corral;
- Against hot, dry or salt-bearing winds, on seacoasts, cliffs or exposed sites;
- As contoured strips to disperse overland water flow to catch silt and to prevent erosion of soils.
Around annual, mulched gardens laboriously freed of weeds, a band of grass-barrier plants prevents weed re-invasion.
There are 4-5 forms of plants which are effective and all of them can be used If space permits:
- A deep-rooted broadleaf (e.g. comfrey);
- A clump grass which does not seed down or is not browsed (e.g. lemongrass, Vetiver grass);
- A carpeting plant such as sweet potato, nasturtium or Impatiens;
- A dense low shrub (Oncoba, Corposma, Echium);
- A bulb such as Canna, Agapanthus.
In total, the same plants can form a fire barrier, provide ample mulch for the garden and if initially cared for, establish in one season. When first placed, they need to be mulched, manured and watered,
Corrals or cattle-goat-sheep barriers can be strengthened with one or two strands of barbed wire, but should have the potential to resist on their own.
Thus, they involve thorny or distasteful shrubs. These can either be planted as a hedge or as a coppice crop which is cut and built into a thorn fence (boma).
The latter enables more flexibility in changing the arrangement of compounds, while the former is less trouble.
Species ideal for such bomas are Lycium ferocissimum, Acacia tortilis, Oncoba spinosa and Euphorbia tirucalli.
Of these, only Lycium and Oncoba may not need trimming. All of these protect diversion banks and compounds from grazing animals.
Euphorbia takes root from cuttings in even arid conditions and Acacia tortilis is ideal for cut and build fences.
When cutting Euphorbia, be sure to protect the eye with goggles and keep the Skin covered if allergic to the milky sap.
Primary tall windbreak of Araucaria, Cupressus, Casuarina, Pinus, hardy Phoenix palms and even mangroves may be needed in front-line locations, followed in the lee with such hardy quickset species as Euphorbia tirucalli, Coprosma repens, Echium fastuosum and so on.
It is always best to find local plant species that do well in the district.
Contours at 10m on medium slopes (2 – 7°) and at 5m on steep slopes can be planted out with root sets of Canna, Vetiver grass, lemongrass or pampas grass.
These are set out at 0.3m – 0.6m spacing and form an un broken cross-slope hedge or a crown on earth walls or dam banks at spillways. (Figure 10.13)
They both disperse water and create silt traps; behind such self-perpetuating walls, soil is deeper and trees can be planted or crops grown.
The system is cheap, effective, and provides mulch. Some of the yuccas, agaves and aloes may provide the some structural effect in desert areas.