Water Management
Water Conservation
A good water supply is critical to maintain healthy plants in your garden. If water is not available to the plant, it cannot photosynthesize and so growth is reduced and the plant will eventually die.
However, mains water use has environmental implications - it uses carbon emissions in it's generation (cleaning, pumping etc) and in times of low supply, fresh water is taken from ground water sources and this deprives our local wildlife of water. So it is important that we are sensible with how we use water, using it only when necessary and saving what we can.
Ways to Use Less Water
Add mulch to planting areas:
A mulch of organic matter like composted plant or animal waste will reduce the evaporation of water from the soil and thus plants will need watering less often. It will get taken into the soil by worms over time and broken down into humus. In this form it helps the soil to hold onto even more water, so it is an invaluable tool for water conservation and keeping your plants healthy.
It has the added benefit of reducing weed growth, reducing the compaction of soil and feeding your plants.
Keep up the weeding:
Weeds also use water so make sure you keep on top of the weeding around ornamental plants.
Right plant, right place
As a designer, it is key for me to create planting plans where plants are only used if suited to the conditions of the site e.g. moisture loving plants in damp soil. Unfortunately when purchasing plants it is not always clear what conditions each plant requires, however there are increasingly good resources online.
Reduce the number of containers
Containers and hanging baskets dry out quickly and so take a lot of watering.
Ceramic/terracotta pots dry out more quickly than plastic ones as they are porous and water is lost through the pot itself. You can restrict this by lining it with plastic.
You could also add a saucer under any container to catch excess water.
Efficient Irrigation
Hosepipes and sprinklers use a lot of water and there is often a lot which falls on areas that don't need it like paths and lawns.
When grass goes brown, it has usually not died - it has dormant buds that remain alive. These quickly start to grow again once the Autumn rains arrive. In dry periods, keep the lawn longer by mowing less. Only under very exceptional circumstances, such as very hot temperatures plus no rain for 2 weeks or more, do you need to water lawns on very light, sandy soils.
A drip or seep irrigation system can be laid to water only those areas that need it. If you add timers or moisture sensors they can be even more efficient.
Established shrubs and trees, herbs and perennials on deep soils should not need to be watered. But in dry periods you will need to water new plants, containers, salads, some fruit and veg, and any plants against high walls.
You can bank up the soil around new plants to create a low point immediately around the plant to hold the water as it soaks in. Also, when planting, if the soil is very dry, fill the hole several times with water and allow it to drain before planting.
Add a windbreak
Wind increases the rate of water loss from plants as well as increasing evaporation from the soil. In an exposed garden, a windbreak can filter and deflect the wind to reduce this effect.
Types of plants used
A mixture of plant types e.g. shrubs, trees, perennials, grasses, will have roots at different depths and so make best use of the water in the soil. To reduce the need to water, use more perennial plants (shrubs, herbaceous perennials, trees) that develop deeper roots and are more able to access water further down, and avoid annuals.
If you are growing vegetables, which need more water than ornamental plants, remember that leafy plants need the most water, followed by fruiting vegetables like beans that need lots of water at flowering and fruiting times, and lastly root vegetables and onions which need less water.
Planning the garden
Make sure any slopes in the garden have planting beds at the base where possible, so that excess water runs onto planting areas rather than onto hard standing and into drains.
Planting time
Autumn is the best time to plant a new garden as the plants will have the whole of the winter to put down deeper roots and acclimatise. They will receive plenty of water through autumn rains and so reduce the need for watering using mains water. Early spring is the next best time to plant, although we can sometimes get a very dry April which is not ideal.
Size of plants to purchase
Whilst it can be nice to purchase a few larger plant specimens to make an impact in a garden, particularly a new garden, it is best to use small plants as these will need less water to establish themselves. I find that 2 litre perennials and 3 litre shrubs are a good size for establishment.
Collecting Water
In a domestic garden, the best way to collect water is by adding a water butt to a downpipe from the house. You can also add them to other garden structures like a shed, garage or greenhouse.
Get the largest water butt that you can afford, or accommodate, as you will be surprised how quickly you run out in mid summer.
Some water from domestic use (grey water) can be used to irrigate plants but you need to be careful of two things, it can contain strong chemicals, and if stored it can accumulate unwanted bacteria.
Water that has been used for personal washing is fine to use as long as it is used immediately, but you need to be careful with kitchen waste water due to the detergents which will have been used.
In any case, taking the above into account, don't use grey water to irrigate vegetables or salads, although fruit trees are ok as the fruit is well above the splash area; don't continually use it in one area of the garden or in pots as the chemicals in it can build up to harmful levels; and avoid acid loving plants as the chemicals can increase the pH.
Managing Excess Water
Periods of heavy rainfall, especially after the soil has been baked hard by hot dry weather preceding it, can cause flooding as the water does not easily soak into the soil.
If water is allowed to run off our gardens, paths, patios and driveways, an increased amount of water goes into the drainage systems. This increases the pressure on sewers, rivers become fuller and eventually river banks are eroded. It can also cause damage to property.
Added to this, more water needs to be transported and processed leading to higher energy usage.
There are several ways to prevent water run-off.
Ensure that hard surfaces slope towards a planted area or that there is a drain that can take water away to a soakaway to allow the water to slowly seep into the soil. (There is legislation regarding front gardens and water run that you should make yourself aware of before undertaking any re-surfacing with hard landscaping)
Add organic matter (composted animal or plant waste usually sold as 'soil conditioner') as a mulch to your beds every spring. This can help to absorb more water and prevent the soil 'capping' with a hard crust in dry weather.
There are increasing numbers of more complex systems to manage water, like underground storage tanks and reed bed systems to purify grey water, but these need to be designed and implemented by professionals and can be costly and space hungry.
If you know an area always gets boggy, a suitable well-positioned tree or shrub such as willow or Cornus can absorb a substantial amount of water, and there are many smaller plants that are suitable for those conditions.