Rising temperatures and months of lower-than-average rainfall spell trouble for UK gardens. Temperatures these days aren’t just warm, they’re hot – Heathrow recorded a temperature of 34.5° in June, the hottest June temperature reading since 1976. Adding to plant stress, rainfall has been below or well below average for nearly all of England.
And it looks like recent dry weather is not coming to an end - the Environment Agency’s latest projections show that large swathes of England will experience groundwater levels “below normal” or “notably low” by September. Bad news for England’s gorgeous gardens. So how can you maintain a lush garden as we face conditions more akin to the Mediterranean, without spending a fortune on your water bill?
How Much Does it Cost to Water Your Garden?
Our research shows that households with a water meter could spend around £20 per month of their household budget by watering their garden for just an hour a day. During a long, dry summer those with a large garden could spend over £100 keeping their plants hydrated. According to OFWAT, around 40% of UK households have a water meter installed, so a significant proportion of households are affected by garden watering costs.
Here’s how we calculated the costs to water a garden. South East Water reports that running a hosepipe for two hours will use 1 cubic metre of water (1,000 litres). Assuming a metered charge for water supplied of £1.30 per cubic metre, every hour of watering would cost £0.65 (£1.31 per cubic metre * 0.5 cubic metre per hour). Over 30 days the watering cost for a garden becomes £19.50, for every hour of daily watering.
When Rain Doesn't Help the Garden
Unfortunately the recent large rainfalls experienced in June don’t necessarily help with a garden’s soil moisture levels. Despite June rainfall totaling 140% of the long term average from 1961-90, the soil is still dry. Particularly affected are the west Midlands and parts of central and southern England, where soil moisture deficits top 100mm. When heavy rains follow significant dry periods, the parched, hardened ground does not easily soak up the rain water. Instead of soaking into the ground to nourish the roots of thirsty, wilted plants, the rain runs off across the surface.
How to Save Water (and Money!) in Your Garden
In an effort to save water and reduce your water bills, follow these tips when caring for your garden.
1. Mulch to Slow Evaporation
A layer of mulch protects the soil underneath from drying out. A number of university studies from America have shown that mulching can reduce water evaporation anywhere from 33% to 75%, which can mean real savings over the course of a summer.
Without mulch, the sun’s heat on the earth’s surface causes the soil to heat up, increasing the evaporation rate. As this top layer dries, moisture from below wicks up to replace it. Before you know it, the soil is dry.
Mulch primarily helps retain soil moisture levels because water cannot easily wick between the soil underneath and the mulch above. Additionally, the mulch acts as a barrier to the soil below, shading it from the sun and keeping it cooler, further reducing evaporation.
2. Water in the Cool Evening to Slow Evaporation
Watering in the heat of the day means higher water bills. Hot soil causes water to evaporate more quickly. That means you’ll need to run the hose longer for the soil to become as soaked and the plants to get the same amount of water as if you watered in the cooler evening (or early morning). By watering in the lower evening temperatures, plants will have time overnight to have a good drink. Your plants will be happier and your water bill lower.
3. Water the Roots
I once asked my husband to water the garden when I was away. He proceeded to spray the foliage of the plants - hard to argue against that logic since that's what rain does. But it's not the most effective strategy for watering your plants. More water ends up evaporating into the air than absorbing into the soil. Plus if only the surface of the earth becomes moist, a shallow root system is more likely to develop.
To increase drought resistance, we want to encourage the plants to develop deep roots. A really thorough soaking of the soil near the base of the plants will do the trick. Water will hydrate the deep, dark soil, far from the evaporating effects of the sun - a welcome haven for a root system.
4. Invest in Drought Tolerant Plants
According to the Office of National Statistics, British consumers spend over £1 billion on plants, flowers and other garden goods every quarter. That’s around £120 per household per year. Buy the right plants and they’re more likely to survive in lower water conditions. A beautiful investment.
Keep in mind some general characteristics of drought-tolerant plants. They often have silver-grey leaves – light in colour to reflect the sun’s rays. You may see little hairs on the leaves, which help to trap moisture (e.g., morning dew). Annuals tend to have larger water requirements, since their root systems are young and undeveloped. You can learn more about drought-resistant plants from the RHS.
Below is a selection of our favourite drought-resistant flowering plants. Plant them to bring beautiful colour to your garden from May to October, all while saving water.
Drought-Resistant Flowering Plants
|Good For||Flowering Months||Name||Common Name||Flower Colour||Approximate Height|
|Borders||May, June, July||Allium||Allium||Purple||0.6m - 1.8m|
|Borders and Pots||July to September||Lavandula||Lavendar||Purple||0.45m - 1m|
|Ground cover, Borders and Pots||May to October||Geranium||Geranium||Various colours||0.45m - 1.2m|
|Borders and Pots||June to August||Scabiosa||Pincushion flower||Various colours||0.6m|
|Borders and Pots||July August & September||Agapanthus||African Lily||Purple||0.6m - 1m|
|Borders||March to August||Euphorbia||Euphorbia||Yellow-green||0.5m – 1.5m|
|Back of Border||June July||Lupinus arboreus||Tree Lupin||Yellow or Purple||2m|
|Borders and Pots||June to October||Calendula officinalis||Pot Marigold||Orange||0.6m|
|Borders and Pots||July to September||Hebe||Hebe||Purple||0.2m - 1m|
5. Collect Rainwater in a Water Butt
Rainwater can be collected in a water butt for use in your garden. The water butt is attached to the drainpipe. When it rains, water runs from the roof into gutters, the drainpipe and into the water butt. It is especially useful for collecting water in rainy, winter months for use in the hot, dry summer months. The RHS estimates that 150 water butts of water could be collected every year from a roof. This water can sustain plants during the 18 weeks from May to September when plants' hydration needs exceed rainfall.
To set up a water butt with existing, closed drain pipes, you’ll need a rainwater diverter kit. These can be purchased at Homebase for £6.29 or at many other DIY stores.