Water Conservation Gardening
Display by Heather Balcomb and Linda De Luca
Water Conservation Gardening is the wise use and management of any water in the garden, particularly rain water. Ideally our gardens should not let a drop of water leave our property - be it a home or business park, or shopping area.
We hope this display gives you visual inspiration on how to implement some principals of water conservation design in the gardens. We have focused on rain water in this display, but please note that many of the principals can also include the management of grey water in the garden. The display includes:
• A succulent garden that demonstrates how these beautiful, drought hardy plants can be used in a garden that is carefully planned to minimize water consumption and water loss.
• A rain garden that illustrates:
- The capture and storage of rain water, slowing it down on its rapid and often destructive path to our rivers
- Methods of spreading it out in the garden to decrease erosion as well as to create more surface area to absorb it
- Methods to assist with its infiltration into the ground
• Elements of wildlife gardening to welcome our smaller co-dwellers to the garden.
There are a number of techniques that can be employed for managing rain water:
• Re-directing water from down-pipes
• Collecting water in rain-water tanks or smaller barrels.
• Creating berms and swales to slow run-off water down .
• Creating rain gardens to collect run-off rain water so that it can be absorbed.
• Reducing impervious cover (e.g. using permeable pavers)
• Creating green rooves (planted rooves)Increasing the health, water retention capacity and permeability of your soil by adding compost, humus and mulch, and grit or small pebbles.
• Carefully considered use of indigenous plants (especially naturally occurring plants)
• Increasing the urban tree canopy to break the force of heavy rain showers.
Creating a rain water garden
• Should be on a gentle downward slope, AWAY from the house.
• Test soil quality for permeability. Dig a 50cm deep hole and fill with water, check how long it takes for the water to seep into the ground. If longer than 24 hours, add mulch, loam and river sand / grit to increase permeability.
• The ideal shape is a tear drop—with the narrowest end nearest the flow of water, and the broad end furthest away.
• Size should be in proportion to the area available and also the amount of water that needs to be trapped.
• The top of the garden should be level, i.e. far end should be built up a little if needs be.
• Cross section of the rain trap should be a gentle “u” shape, about 50 cm deep and width and length in proportion to the garden.
• Fill the base of the basin (15 to 20cm) with gravel to aid drainage.
Plants to use
It makes sense to use locally available indigenous plants, as these will be most suited to the environmental conditions in your garden.
• Beauty and functionality - it is very important that the garden is aesthetically pleasing to you, as well as working effectively to trap rain water.
• Tolerate both ponding / saturation from rain water accumulation and drought. Collected water should not stand for longer than about 24 hours
• Creating wet and dry zones. Group plants so that they will thrive according to their water requirements.
• Wildlife value. Locally indigenous plants will have the added value of being the natural food source for local wildlife.
Ensuring that rain water is slowed down naturally before it rushes into our rivers has a number of advantages:
• If enough people in a neighbourhood do it we could actually contribute towards recharging the groundwater and thus raising our water table.
• Plants and soil etc. that slow the run-off down also serve to filter out some pollutants including chemicals and trace metals. Plants’ roots in particular can sustain various microbes that assist in bio-filtration, resulting in cleaner water being released into the environment.
• The more water that soaks into the ground, the less water will enter the drainage system at any one time. It will be released gradually. The positives to this are that nearby stream water quality can be improved. River beds will not be scoured out as regularly, and aquatic biodiversity will be able to establish itself and thrive. The other advantage is that it prevents large scale erosion due to the force of water movement.
As water is a precious (and increasingly more expensive) resource we need to shift our gardening style to maximise the amount of water that is trapped on our properties with some relatively small changes. By creating small berms, swales and dips one can slow water down sufficiently to ensure that most of it will soak into the ground, depending on the soil type. Some soil conditioning can greatly enhance the soil’s capacity to absorb the water. On a larger property or in a business park, Rain water depressions (rain gardens) could be created in a series down the slope, and be connected by swales or French drains so catch any overflow from one to the next..
The Succulent Garden
Succulents have been described as the “retro” plants of today - with shapes, colours and textures that fit in well with the modern, simple style of décor and home design. As gardening takes on a more environmentally conscious approach, aspects such as water conservation and wildlife gardening are incorporated into the design.
Whether you have or would like to install a more conventional rock garden or something more modern, here are some tips for creating a beautiful succulent garden.
Soil type and soil scaping
Succulents are not very fussy about soil type (just not water retaining clay) as long as it is healthy and well drained . To ensure that soil does drain well one can condition it with the addition of sand and loam, and shaping soil so that you create undulations assists with the drainage of soil. When creating a rain water harvesting garden, succulents are an excellent addition to the drought hardy section of planting that does not ever have soil saturated for a prolonged time. A little natural, slow release 2:3:2 fertilizer can be added once or twice a year, as well drained soil can mean that many nutrients are leached out.
Although succulents are low-water in their requirements they are not “no-water” plants. All plants need some water. Succulents are well adapted to long dry periods , and a general rule is that the more fleshy and “fat” they are, the more drought hardy too. To keep them looking their best, water succulents through long dry periods, letting the soil dry out between waterings. NEVER over water.
Plant succulents together with some non succulent plants for striking effect. In nature, you may often find grasses, drought hardy small shrubs and bulbs associated with succulents. Copy nature and be rewarded with beauty and increased variety of wildlife visiting the garden.
Use containers to either enhance or raise succulents in your garden, or to add repetition to your garden planting - one of the key successes to good garden design. If space is short for putting in an entire large succulent garden, containers planted up with miniature gardens can be hugely successful.
Consider the garden users
The more habitat you create in your succulent water conservation garden, the greater the variety of visitors you are likely attract. Include rock, wood and water in your garden, as well as areas of mulch where some creatures will be able to enter the soil.
Again one of the key elements of good garden design, it does need to be in keeping with the style and feel of the rest of the garden. ALWAYS consider putting a focal point in the garden. Plant this first, and then continue planting around it.
Repetition creates rhythm in the garden and ties it together beautifully. Repetition can be in the form of plant species, shape or form, colour or in the containers that you use. Repetition creates visual simplicity, and this will enhance the harmony in your garden.
Group plants together for stronger effect. Make a statement with a couple of the same species of succulents. This is particularly impactful if you use plants with different leaf and stem colours.
Succulents come in an array of shapes, textures and colours. Contrasting these against each other can accentuate their features, providing variety and interest, but always keep the harmony of the design in mind.
Height and Scale
Be aware of the eventual size of plants newly planted in your garden relative to the size of your garden and other planting. Tall, bold succulents are wonderful focal points, but keep their scale in proportion to the size of your garden. When planting, leave space around younger large plants to accommodate their eventual size.
Using Rock and other accessories
Apart from creating interest in the succulent garden, accessories such as rock, pebbles, driftwood, create habitat for wildlife. Accessories such as pots and sculpture can even be used to create a focal point or enhance a plant that is the focal point. Keep accessories in context with the rest of the design.
Ultimately, whatever garden style we choose to adopt in our gardens, we should endeavour to act sustainably, conserving energy and water in every way possible. By preserving natural habitats and incorporating all or at least some elements of ustainability in our gardens we can maintain the biodiversity that urbanisation so often displaces and often exterminates.
Wouldn’t it be wonderful if we could work together with our neighbours to turn Johannesburg and its surrounds into a flourishing environment, with healthy waterways, gardens and open areas that can sustain a biodiversity second to none.
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