Just like people, plant roots need air and water in order to survive. Watering your garden is a balance between getting enough moisture to your plants’ roots and not over-watering which will drown them.
The ideal for most plants is “moist but well-drained soil”. This means that there is both air and water between the soil particles (where the roots are growing). It’s better to water your plants thoroughly but less frequently, rather than giving them a splash every day. This encourages plants to root deeply and to establish themselves well, and avoids wasting water.
Often in gardens we have either too much or too little water. However, there are lots of ways gardeners can get round these problems.
Harvesting the rain
Installing water butts is a useful way to make your garden more environmentally friendly. Harvesting rainwater reduces mains water use and is better for your plants than mains water. It can also help reduce pressure on drains during periods of intense rain. Install as many butts as you can; you’re unlikely to fulfil all your garden’s needs but it’s a start.
If you don’t have space for a water butt, you can improve the water holding capacity of your soil by adding organic materials such as homemade compost or well-rotted manure, so when it does rain, more water stays in the soil rather than draining away.
If you have the budget to do it, install a domestic rainwater-harvesting system; these can easily fill an underground tank holding 6,500 litres (more than 30 ordinary water butts) from the roof of most homes.
Gardens can play an important role in helping to prevent surface water flooding in urban areas. Our green spaces soak up the rain - unlike paving, tarmac and concrete, which are less porous and increase the amount of rainwater that runs off. This surface run off water often flows into street drains, and sometimes into sewers which can’t always cope, and excess water can then go back up the pipework to flood their homes and gardens. To help alleviate this problem, use permeable paving and keep impermeable surfaces to a minimum.
Find out more about permeable paving
While it’s relatively easy to stop overwatering your plants, waterlogging and flooding are more of a problem. If they happen in winter, when most plants are dormant, the damage can be more difficult to spot, but with summer floods, symptoms such as wilting, yellowing and browning of the leaves usually appear rapidly. Either way, the roots suffocate because of the lack of oxygen, then they drown and rot, paving the way for diseases such as Phytophthora.
If your garden regularly gets waterlogged, there are a few things you can do. Luckily, there are quite a few plants that are especially adapted to grow in poorly-drained soils – see our Find a plant database for lots of ideas.
Create raised beds and plant trees and shrubs on mounds. This helps to lift roots above the water tables, and provides some protection against flooding. Poor drainage on clay soils can be improved by cultivation, such as digging in compost or using organic mulches.
Similarly, water lying on lawns can be encouraged to soak in by aerating and increasing earthworm abundance to create mini-drainage channels. To encourage healthy populations of worms, avoid using garden chemicals and leave grass clippings on the lawn. In the worst cases, you can lay perforated plastic drainage pipes in the ground to move water to soakaways.
Tips on saving water
See practical tips on designing and planting a garden to manage water effectively
- Dig in organic matter such as well-rotted garden compost – this helps your soil retain extra moisture and can provide plants with the equivalent of an additional 5cm (2in) of rain: about 20 days’ supply for many common garden plants
- Prepare your soil in autumn or winter rather than summer as it will lose less moisture
- Apply a mulch such as bark chippings in late winter to help lock in water.
- When planting a tree, after preparing the hole, first fill it with water 2-3 times and let it drain down to the base before planting the tree, re-filling soil around its roots and adding a layer of mulch on top. This will ensure good soil moisture levels near the roots, encouraging deep root growth and resilience to drought, while reducing evaporation
- If your garden is prone to flooding, consider making raised beds. These allow the soil to drain well and help plants survive flooding, but be aware that plants in raised beds will need more watering than those in the ground
- Put saucers under containers to catch runoff, remove all weeds from containers (they use water, too) and use ‘grey water’ where possible
- If you purchase an automatic irrigation system, try to select one with sensors that turn off the water when it is raining or when the soil is too moist. Position the probe carefully and be aware that the settings may have to be adjusted for your soil type
Few garden plants will survive prolonged periods in ground saturated with water.
Read our advice below for care tips and plant choice.