uk; gardening matters: how can gardeners save water and money

8/3/2019 UK; Gardening Matters: How Can Gardeners Save Water and Money

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WATER IN THE GARDENAre we draining our water supplies?

How can gardeners save water?

WATER SERIES

Gardening

Matters

SPONSORED BY


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WATER IN THE GARDEN2 FRONT GARDENS

WATER, WATER, EVERYWHERE?Gardeners use about two-thirdsof the domestic water supplyduring dry spells. Discover whythis can be a problem for theenvironment and why hosepipe

bans were introduced insouthern England during 2006.

WISE WATERINGFrom sprinklers to wateringcans, there are many waysto water. But which makethe best use of water andhow often should plantsbe watered anyway?

HOW TO SAVE WATEREven in the smallest garden,it is possible to reduce theamount of tap water neededto keep plants thriving. Thesesimple solutions show you how.

SOME LIKE IT HOTGardeners can choose froma wide range of plants that

will tolerate dry conditions.Find out how to spot themat the garden centre.

CONTACTS AND RESOURCESWhere to buy and who tocontact for information.

JOIN THE RHS AND SAVE 5Enjoy the benefits of

membership for just 39.

14

13

12

9

6

2

CONTENTS


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WATER IN THE GARDEN 1

WelcomeMake every drop of water count

Up to 70 per cent of our domestic water supply is

poured and sprinkled on to our gardens during peak

summer periods. This huge demand is hard to sustain

in a drought. So after 16 months of less-than-average

rainfall, hosepipe bans were introduced into many

parts of southern England in 2006. Although irksome

to gardeners, hosepipe bans help reduce waterdemand and help prevent the introduction of more

stringent measures.

Even without using a hosepipe, it is still possible

to have a beautiful garden. Starting on page 2,

discover why plants actually need water and why

it is important to grow plants that arent too

demanding. From page 6, find out how to create

an attractive garden without draining mains watersupplies in hot weather.

Gardeners shouldapply water when it is

needed and in waysthat ensure every

drop countsGUY BARTER

Head of the RHS Advisory Services


4/16

Every gardener knows that plants depend on water

and that without it they will suffer and die. This isbecause most plants consist of 90 per cent water,

and their roots have a constant battle to maintain this

level during hot spells. On a single sunny day, about

two litres of water are lost from every square metre

of vegetation whether grass, shrubs or even potatoes,

the water loss is similar. This is often replenished by

summer rainfall and just 25mm every five to ten days

is generally sufficient to keep plants growing well. But

in dry periods it has to come from reserves in the soilor from watering by a gardener.

Water, water, everywhere?Gardeners have been used to turning on the tap andcasually watering their plants, but can this continue?


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Apart from preventing plants wilting, water is used to

make the food needed for growth. In a sun-powered

process called photosynthesis, water is combined withcarbon dioxide from the air to make sugars. The

carbon dioxide gas enters plants through pores called

stomata. These need to remain open in the day to

allow the plant to photosynthesise but, unfortunately,

this also allows water to evaporate freely. So, as water

becomes more scarce, the stomata close. This reduces

photosynthesis and, without food, growth slows too.

If the roots cant take up enough water, plants will wilt,

lose their foliage and finally die.

Luckily, most soils have an amazing ability to store

rainwater. Rain initially fills the spaces between the

soil particles, but there is usually a surplus in winter

that drains deeper into the ground and eventually into

rivers. These soil water reserves are usually drawn upon

by plants from May onwards, and by late summer they

will have used them up. This can often lead to wilting

and a reduction in growth.

This is not to say that watering is necessary for all

plants in late summer. Knowing which plants need

it most (see page 8) and which can be left to find

their own will save water. Plants are robust and have

developed techniques for surviving periods of drought.

For example, grass has dormant buds that remain

alive even when a lawn has gone brown. These

quickly start to grow again once the autumn rains

arrive. As a result, most lawns can be left unwatered

without causing long-term damage, unless its a very

fine turf that is less able to recover.

The RHS believes that much of the watering carried

out in gardens is the result of a misunderstanding

about how and when water needs to be applied.

An excessive amount is often used, which then simply

drains out of reach of the roots. On the other hand,

insufficient water sprinkled on the soil merely wets thesurface. To be sure of effective watering, see page 6.

USING RAINWATER

How many water butts are

needed to keep a garden

green in summer?

Of course it depends on

what you are growing.

If you have five medium

containers of bedding plants

for example, you might haveto give each of them two

litres of water every day

during the 18 weeks from

May to September. This

amounts to six 210 litre

water butts. Fortunately,

a years worth of rain falling

on a shed (2m x 3m) could

supply this. Indeed, up to1812 water butts could be

filled in southern England

where 650mm of rain falls

each year. Even in the summer

months there is the potential

to gather 1000 litres. This

would fill five butts just one

short of the six butts needed

to water the five containersover the summer.


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WATER IN THE GARDEN4

Britain is often said to be wet, with rain falling fairly

evenly throughout the year. But, in truth, there is

not enough rain to supply all of our needs in drysummers, especially in the south and east of England.

Two-thirds of our water is drawn from rivers and

reservoirs, which can become greatly depleted by

late summer. The remaining third comes from aquifers

(water-holding rocks). Too much extraction (technically

called abstraction) from the latter causes springs to

dry up and this harms rivers and wetlands and the

wildlife that depends on them.

Taking more water from the environment can lead

to severe damage, and permission to extract is

increasingly hard to obtain. Unfortunately there are

few unexploited rivers and aquifers left in many parts

of Britain, and building more reservoirs is likely to be

unpopular. Much has already been done to reduce

water losses from leaking pipes, but there is scope

to do more.

The problem is compounded by the fact that peak

demand for gardens is on summer evenings after

about two weeks without rain. At this time, garden

water usage leaps from an annual average of 36 per

cent of the total water supplied to 5070 per cent.

Even in normal summers suppliers can struggle to

meet demand, but in drought periods they may seek

to curb water use with hosepipe and sprinkler bans.

Hopefully, this helps to prevent the introduction of

more stringent measures, such as those allowedunder Drought Orders.

Water supplies in south and east England are

particularly stretched. The population is increasing and

more homes are being built. Plus more water is being

used per person due to lifestyle changes, such as the

increased use of water-hungry appliances and more

smaller single occupancy households. This is despite

these areas having the UKs lowest rainfall. Eventuallythis could lead to demand exceeding supply.

Top:Along with many water

companies, Thames Water is

replacing broken pipes to help

prevent leaks.

Below:Extracting too muchwater from aquifers can harm

wetlands and rivers used by

wildlife such as otters.

Across:Thames Water Reservoir


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The situation around the country is also predicted

to worsen as climate change takes effect. Summers

will become hotter and drier, and annual rainfall will

decrease (especially in southern and eastern England).

Short-term data already suggests that this is happening(discover how to learn more about climate change on

page 13), so unrestricted water use in British gardens

is unlikely to continue.

This does not mean that gardening is doomed

when no rain falls. By storing rainwater, choosing

drought-tolerant plants, using the right watering

equipment and making every drop count, gardeners

can play their part in conserving water supplies whilestill enjoying their gardens.

Help the soil to store water

by digging in or mulching

with organic matter, such as

well-rotted manure. This can

provide the equivalent of

5cm of rain or 20 days supply.

Deeply digging beds or using

raised beds will increase the

volume of soil from which

plants can take moisture.


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Wise watering

Watering is not complicated,but there is more to it than justshowering thirsty plants. Hereare some tips on how to waterplants effectively and when towater for the best results

Good watering aims to supply enough water to

replenish soil levels without overdoing it. Apply it

at a steady rate at the base of stems and beneath

the canopy of foliage, as wetting the leaves is a

waste. The surrounding soil should stay dry, with all

the water going where it is needed to the roots.

Keeping much of the soil surface dry will also help

to limit weed problems.

There is little point in applying excess water, as it

will quickly drain below where the roots can reach.

So always check the weather forecast and only water

if not enough rain falls. Watering in the evening gives

it time to sink in while evaporation rates are low.

Unfortunately, summer evenings are times of peak

water demand. It is often better to water early in the

morning, as water pressure is high and demand low.

Water restrictionsDuring a hosepipe ban, hoses, sprinklers and irrigation

systems cannot be used to apply mains water to

plants. Legally you are allowed to use a hosepipe for

siphoning grey water or water from tanks and butts.

Short lengths of hose can often be used to fill watering

cans, containers and tanks to dip watering cans into.

(These restrictions may vary, so always check withyour water company.)

USING GREY WATER

Plants can be watered

with bath, shower, kitchen

and washing machine

water (but not dishwasher

water), which is collectively

referred to as grey water.

A washing machine can use

50 litres per wash over

five watering cans worth.

Grey water varies in quality

and usually contains some

degree of contamination.

However, soil and potting

compost is effective at

filtering out contaminants,

including soaps and

detergents. There shouldbe no problem with the

small-scale, short-term use

of grey water to tide plants

over during a summer

drought. Long-term,

extensive use (particularly

of softened water) or

the permanent altering

of plumbing should not

be attempted withoutexpert advice.


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Ways to waterThere are many ways for a gardener to apply water, and here we explain the pros

and cons of different methods and the types of equipment widely used

Sprinklers, including pop-up and micro sprinklers,

have a limited range of uses in most gardens these

include watering lawns where essential and raising

moisture levels of large areas ready for planting.

Sprinklers are prohibited during a hosepipe ban.

Hosepipes produce large droplets or jets of water that

can damage the surface of the soil, resulting in water

just running away from plants. This can be solved by

attaching a lance or spray head. Also avoid leaving

hoses trickling beside plants, as the excess water just

drains away. Do not use during a hosepipe ban.

Irrigation systems based on seep and drip hoses

allow water to sink slowly into the soil, but they should

only be left on long enough to wet the top 30cm of

soil. On sandy and gravely soils there is little sideways

movement of water and nozzles should be fitted to aid

dispersion. Such systems can only be used to applygrey or collected rain water during a hosepipe ban.

Watering cans without a rose attached behave like

hoses, but are more work! With a rose on, there is less

soil damage and little run-off. Ponding (see below)

increases the effectiveness of watering cans.

Buckets are like watering cans, but quicker to empty.

Used clumsily, they can damage the surface of the soil.

Ponding means using banks of soil to hold water

around a plant while it soaks in. In a similar way you

can grow vegetables in trenches that can be filled with

water. And sink flowerpots into the soil next to plants

to create a funnel that will direct water to the roots.

Puddling is the placing of new plants into their

planting holes, and then filling the hole with water

several times. The soil is then firmed back around the

rootball. This method locks in sufficient moisture tosustain the plants for several weeks.


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When to water?When do plants need water? The best guide comes

from digging 30cm into the soil. If it feels damp at

this depth, watering is not needed, but if it feels dry,then some plants will need a drink. Gardeners should

be aware that clay feels slightly damp when all the

available water has been used, and sandy soil is dry

to the touch even when some water is available!

It just takes a little experience to get used to this.

Fruit and vegetables will usually crop adequately

without watering. The quality and quantity, however,

is improved by watering at times when drought would

affect the part of the plant that is harvested. When

leaves are the crop, such as lettuce, the plants should

never go short of water. In practical terms, watering

about two weeks before harvesting is usually sufficient.

Containers need frequent watering because they only

hold a limited amount of water. Apply water when the

surface of the compost appears dry. You can tell if you

have given a pot enough water when the excess flows

out of the bottom. A saucer will retain this run-off.

WATER WHEN THESOIL IS DRY

WATER EVERY 1014 DAYSIN DRY PERIODS

WATER SELDOM NEEDED

Perfect lawns

Leafy salads; peasand beans in flower

New plantings

Containers andhanging baskets

Borders next tohigh walls

Plants in drought-pronesandy soils or sticky clays

Most vegetablesand fruit* (except those

mentioned right) Bedding plants

Drought-tolerant plants(see page 12)

Most lawns, wildflowermeadows and established

trees and shrubs Large fruit trees, currant

bushes, carrots, parsnipsand herbs**

Established perennialson deep, sandy loamor clay-loam soils

* More water needed on sandy soils**On drought-prone sandy soils or sticky clays, water every 1014 days in dry spells


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How to save water

Most of us think about making our gardens look

beautiful, but how many of us ensure it does not

need much watering?

With just a bit of thought, its possible to reduce the

amount of water needed to keep plants growing and

to minimise the labour involved in applying water. To

begin with, it is important to understand your garden.

Is it in a dry part of the country (including southernand eastern England) and does it have free-draining

soil that rapidly dries out in summer? If the answer is

yes, then it is worth planting drought-tolerant plants

to begin with (see page 12). Of course, you may still

want to grow a few thirsty plants, such as lettuces and

delphiniums, so it is best to use water-saving features

and techniques too. To explain how all this works

in practice, read the following two examples. The

individual ideas can be used in any garden, but theyreally help to save water when they are combined.

Reducing the amount of water needed to keep a gardengreen and growing is surprisingly easy. Here are somesimple ideas for family gardens and container displays.

CHECKLIST

Prepare soil in autumn and winter to minimisemoisture loss

Install water butts to collect rain

Mulch in late winter

Recycle kitchen water

Grow drought-tolerant plants

Put saucers under containers

Limit the number of hanging baskets

Avoid watering lawns

Remove weeds they use water too

If possible, plant in spring or autumn


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Container displays

To reduce the water needed by containers, try

grouping them together. This allows the plants to

shade each other and, as a result, less moisture will

be lost from their leaves. Also place a saucer under

each pot to collect water that would otherwise run

away. This reservoir will be absorbed by the plants.

If you have a choice, position your containers in a

sheltered spot near the kitchen so it is easy to use

grey water(see page 6 for details of what can be used).

As well as watering by hand, containers can

be connected to an automatic irrigation system.

Set to deliver the minimum amount of water, it is

economical and can water while you are on holiday.

However, this is not permitted during a hosepipeban except if it uses grey water or stored rainwater.

GET DESIGN HELP

If you would prefer to use

a professional designer to

help plan a water-efficient

or drought-tolerant garden,

contact the Society of

Garden Designers for a

list of their members

(see page 13 for details).


13/16


Family-size gardens

To keep the task of watering to a minimum, mulch the

surface of the soil in late winter. This will help to keep

as much water in the ground as possible during dry

weather. Thankfully, mature trees and shrubs do not

need watering. Likewise a lawn can be left to brown,

although small areas are worth watering to help thesurface resist the heavy wear of children playing.

Water butts are invaluable. They can store run-off from

the roofs of houses, greenhouses and sheds, fit neatly

against walls and can be placed near vegetable beds to

make watering easy. When the butts are running low,

save the water for edibles such as vegetables and herbs.

Other thirsty plants such as bedding can be watered

with grey water. After prolonged spells without rain, it

is prudent to discard the first bucketful of water, as thismay contain dust and other pollutants from the roof.


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Some like it hotChoosing plants to cope with dry conditions need not be daunting. Just look out forthose with the following drought-tolerant characteristics, or ask for advice at gardencentre help desks. Dry shade can be particularly tricky, so there is a list of plants below

Spikes act as coolingfins, ensuring plantslike Acanthus spinosus(bears breeches) andEryngium oliverianum(sea holly) loseheat but not toomuch water.

Small leaves shedheat and have fewpores from whichto lose water.Good examples areRosmarinus officinalis(rosemary) andThymus(thyme).

Leathery foliageloses less water thansoft leaves. Look outfor plants such asSalvia officinalis(sage) and Cistus(rock rose).

Grey leavesusually signifydrought resistance.They can typicallybe seen on Artemisia,Lavandula(lavender),and Verbascum(mullein).

Hairy leaves shadethemselves with theirown hairs Verbascumbombyciferum andStachys byzantina(lambs ears) arejust two easy-to-grow examples.

Long, narrow leavesare very good atshedding heatwithout losing water.Plants with theseinclude grasses(eg Helictotrichonsempervirens)and phormiums.

Fleshy, succulentleaves store moisturefor dry spells. Sedumspectabile(ice plant)is a hardy example,while Aeonium canbe grown outdoorsin summer.

Aromatic leavescontain volatilescented compoundsthat are thoughtto cool foliage asthey evaporate,reducing waterloss. Try CistusandLavandula (lavender).

More advice can be found at www.rhs.org.uk. From here, you can also click on tothe RHS Plant Finder, which lists more than 70,000 plants and where to buy them.Theres also the RHS Plant Selector, which can help you choose drought-tolerant plants.

PLANTS FOR DRY SHADE

Berberis darwiniiBuxus sempervirens(box)Euphorbia amygdaloidesvar. robbiaeHedera helix(common ivy)Hypericum calycinum (rose of Sharon)Ilex aquifolium (holly)

Lamium galeobdolon (dead nettle)Mahonia aquifolium (Oregon grape)Ruscus aculeatus(butchers broom)Sarcococca hookerianavar. humilis(Christmas box)Vinca major, V. minor(periwinkle)


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CONTACTS AND RESOURCES

FIND OUT MORE

THE RHS

Practical gardeningguidance andinformationon grey water.www.rhs.org.uk/advice/watering.asp

THAMES WATERUTILITIESFor more watersaving tips.Tel 0845 9200 800

www.thameswater.co.uk/waterwise

CENTRE FORALTERNATIVETECHNOLOGYTel 01654 705950www.cat.org.uk

ENVIRONMENTAGENCYFor a wider view

of UK water resourcesTel 08708 506 506www.environment-agency.gov.uk

The website also listsinformation that canhelp with recycling greywater. From the homepage,put grey water into thesearch engine. Theresults will show all

available resources.

SOCIETY OF GARDENDESIGNERSTel 01989 566695

www.sgd.org.uk

WATERWISEAn organisation thatencourages thereduction of waterconsumption.Tel 020 7344 1883www.waterwise.org.uk

WATER UKAn organisationrepresenting thewater industry.Tel 020 7344 1844www.water.org.uk

RAINWATERCOLLECTION

3P TECHNIK UK LTDTel 0870 1162060www.3ptechnik.co.uk

EVEN GREENERTel 0845 658 5588www.evengreener.com

FREERAINTel 01636 894906www.freerain.co.uk

UK RAINWATERHARVESTINGASSOCIATIONwww.ukrha.org

WATER SUPPORTSERVICESTel 01305 266614

www.water-support.co.uk

WATERINGPRODUCTS& EQUIPMENT

CARRY ONGARDENINGAdvice on wateringequipment for elderlyand disabled gardenersfrom the gardeningcharity Thrive.Tel 0118 9885688www.carryongardening.org.uk

GARDEN WAREHOUSELarge/wholesalequantities of equipment.Tel 01282 873370www.lbsgardendirect.co.uk

HARRODHORTICULTURERainwater tanks,butts and pumps.Tel 0845 218 5301www.harrodhorticultural.com

N A KAYSLarge quantitiesof equipment.Tel 01946 692134www.kaysdiscountgarden.co.uk

SIMPLY CONTROLWide range ofwatering equipment.

Tel 01796 482128www.simplycontrol.com

TWO WESTSAND ELLIOTTWide range ofwatering equipment.Tel 0870 4448274www.twowests.co.uk

CLIMATE CHANGE

THE UK CLIMATEIMPACTSPROGRAMME(UKCIP)INFORMATIONAND PREDICTIONSInformation andpredictions.Tel 01865 285717www.ukcip.org.uk

RHS GARDENINGIN THE GLOBALGREENHOUSEwww.rhs.org.uk/research/climate_change/index.asp

The mention of anyproducts, suppliers orservice does not constitutean endorsement bythe Royal HorticulturalSociety.

Water in the GardenAdvisory ServiceRHS Garden WisleyWoking, SurreyGU23 6QBTel 01483 224234

2007

EditorGuy Barter

Project ManagerLeigh Hunt

DesignerSweeta Patel

IllustrationCorin Page

PhotographyCover: SheilaTerry/Science PhotoLibrary; Contents:Flowerphotos; p1: FPLA& Garden PictureLibrary (GPL); p2: FPLA(top) & RHS Wisley; p3:GPL; p4: Thames Water

& Duncan Shaw/Science

Photo Library;p5: Thames Water;p6: GPL; p7: GPL & GuyBarter/RHS (bottom);p8: Flowerphotos;p9: GPL & RHS HydeHall (bottom); p11:Flowerphotos; p12: RHSHyde Hall (left) & GPL;

Back Cover: RHS

The Royal Horticultural Society is the UKs leading gardening charity | |www.rhs.org.ukRegistered charity no 22879

Printed with vegetable-based inks on 130gsm Generation Skye Coated Extra Matt (chlorine free and from sutainably-managed forests)


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uk; gardening matters: how can gardeners save water and money

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