gardening with water in mind

8/2/2019 Gardening With Water in Mind

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30 The Organic Way 187

Writing a piece like this is every garden writer’s

nightmare. If I extol the virtues of all the

drought resistant plants I can think of and

write about every known way to save water, then 2007

is bound to be the wettest summer since records began.

So much easier to write about how to grow squash or

peonies or to describe that lovely garden I visited one

perfect summer day last July. But water conservation isn’t

only relevant in drought years: a water-wise garden will

survive the over-wet periods as well as the over-dry ones

with less intervention by you.In Goulburn, New South Wales, all

outdoor use of water is banned because

of the extent of the drought there.

A healthy respect for our own water

supplies shows a healthy respect for

these people, and millions of others

around the world trying to grow food

with less than abundant water.

What do plants do with water?So, what exactly does a plant do with all that water? Just

how much is necessary. and why? Well, broadly speaking,plants use most of the water they take up to transport

nutrients from the soil to the part of the plant that needs

them. Much of the water absorbed from the soil is then

‘transpired’ through the leaves in a process that is a little

like humans sweating. A large deciduous tree can get

through as much as 9000 litres on a hot dry day!

Water evaporating from the leaves helps to keep

the plant, and the air around it, cool, and explains why

grass feels cool on your feet on hot days. Water is an

essential component of plant growth. When combined

with carbon dioxide from the air, during photosynthesis,

sugars are produced that form the building blocksfor all plant growth processes. In fact, growth actually

slows down on a hot, dry day. As the stomata (tiny

holes on the leaf surface) close to limit water loss this

also limits carbon dioxide intake and slows down the

photosynthesis process.

Furthermore, plants stressed by too much or too little

water are far more vulnerable to attack by pests and

diseases, such as aphids and powdery mildew.

Water storage – in the soilYour first step to a water-wise garden should be to

improve the water holding capacity of your soil. Water

stored in the soil itself cannot easilyevaporate and is instantly available

to your plants. Bulky organic matter

improves both the water-holding

capacity of soil and its structure. Well

structured soil is better able to hold on

to nutrients and release them to the

plants growing in it, so it’s good organic

practice on all fronts.

Bulky organic matter does not need

to be a rich fertilizer such as garden compost or well

rotted manure. In fact, these should only be used where

A large tree can transpire as much as 9000 litres of water on a hot, dry day.

© C

a r r i e P a i l t h o r p e

Adding bulky organic matter to your borders improves its ability to cope with flood or drought.Adding bulky organic matter to your borders improves its ability to cope with flood or drought.

Gardening

with Water in Mind

‘Using minimum-dig

techniques

also helps reduce

water loss’



The Organic Way 187 31The Organic Way 187 31

feeding is necessary – too much of these nitrogen-rich

additions is not recommended. Elsewhere, low fertility

soil improvers such as leafmould or green waste compost

are the best additions.

Miraculously, a soil improved in this way will also have

good drainage and will be better able to withstand a rainy

season as well as a drought. Because the organic matter

helps to bind the aggregates in the soil (the sand, clay, andsilt) into larger lumps or ‘colloids’, the gaps between the

colloids are correspondingly larger, leading to improved

drainage. Any excess water then drains away easily so

the ground does not become waterlogged. But it is this

organic matter that also acts as a sponge and soaks up

lots of available water for slow release to your plants.

Retaining the waterHaving improved your soil as much as possible on as

many of your beds as possible, including ornamental areas,

vegetable beds, and around any fruit trees and soft fruit,

you should turn your attention to retaining as much of

that water as possible by slowing down evaporation from

the soil surface. This means mulching.

Lots of different materials are suitable; see the table

for an idea of the advantages and disadvantages of each

type. Some look better than others and some are more

‘environmentally friendly’ choices. You must decide whatwill be right for your garden, but remember: any mulch is

better than no mulch.

Using minimum-dig techniques also helps reduce water

but cutting down on all soil cultivations such as hoeing.

Try to do only what is necessary to keep the weeds

down – they’ll compete with your plants for the available

water – as less disturbance of your soil means less of it is

exposed to drying air currents.

Mulch Pros Cons

Water-permeable landscaping fabricGreat for new beds, look goodwhen covered with gravel orornamental bark

Difficult to apply to establishedbeds, non-renewable resource

Compost, well-rotted manure,leafmould, green waste compost,

spent hops

Free or cheap resource, recycling,feeds and conditions soil as well as

retaining moisture

Need renewing, may contain weedseeds

Newspaper, cardboardFree resource, recycling, adds tobulky organic matter content of soil

Functional appearance, needweighing down

Fresh grass clippingsFree resource, recycling, adds tobulky organic matter content of soil

Can burn delicate plants, use aroundfruit trees and woody shrubs

Composted grass clippingsFree resource, recycling, adds tobulky organic matter content of soil

StrawAvailable in large quantities, adds tobulky organic matter content of soil

Functional appearance, organic strawis very hard to source

Gravel Looks good, lasts foreverExpensive, may not be sustainablyquarried

Fit water butts to as much of your greenhouse as possible. Fit water-catching containers to as many of your buildings as you can.

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Water

Compeafmo

spent

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Comp

Straw




Harvesting waterYour next line of defence against drought should be

to harvest as much rainwater as possible. Most water

authorities now offer water butts at subsidised prices.

You can also buy some rather smart wooden affairs

from garden centres and online suppliers, or reuse anysuitable container you can get your hands on.

Make sure all water butts are covered.

This prevents any nasty accidents to

children, wildlife, and pets; it stops the

water becoming a mosquito breeding

ground in the height of summer; it

keeps out leaves and other debris, and

excluding the light prevents the water

from turning green.

Try to fit butts to every available

downpipe on your house and garage; on

sheds and greenhouses install gutteringconnected to butts. Most butts only hold around 200

litres so you may need to connect several together

to see your garden through a severe drought. If rain is

forecast in a dry spell, pop outside and fill up as many

watering cans as possible from your butts – this leaves

spare capacity in the butt for more water.

More financially advantaged readers could

consider installing underground storage tanks, taking

rainfall directly from their roofs to an evaporation-

proof container. We have one under the Vegetable

Inspirations Garden here at Garden Organic Ryton.

You can also install such tanks under greenhousestaging, as we have in our Paradise Garden.

GreenhousesSpeaking of greenhouses, these can be one of the

most water-hungry areas in the garden. Seedlings

are very vulnerable to ‘damping-off disease’ – a

catch-all term for a variety of fungal infections that can

kill an entire tray of seedlings in hours. Because of thisdanger, water seedlings with tap water only because

the water company’s treatment will

have eliminated almost all pathogens.

Once your seedlings are past the first

potting-up stage, you can safely use

harvested rainwater.

Never place pots directly on

your greenhouse staging as much

of the water applied to them will

simply drain off. Invest in capillary

matting or gravel trays for greenhouse

staging to prevent runoff whenwatering and to enable plants to access this

water when needed.

On the market are many automatic watering

systems suitable for use in a greenhouse. These range

from inexpensive ‘watering spikes’ to entire systems

with porous hose and timers. Some can use harvested

rainwater or be connected to water butts. However,

some need connecting to the mains, and this would be

illegal during a hosepipe ban so think carefully before

deciding which system to buy. Simple measures such

as putting plants in a spot that is shady at midday and

making full use of gravel trays and capillary matting willreduce the need for watering.


© H

o z e l o c k L t d

Built-in water storage in Ryton’s Paradise Garden Alitex greenhouse.

‘Never place pots

directly on your

greenhouse staging ’

Soaker hose enables you to make sure water goes where its needed.



The Organic Way 187 33The Organic Way 187 33

Reusing waterIf all your beds are enriched with organic matter and

mulched, and if as much as possible of the rain falling on

your property is being harvested and stored, only then

should you consider using grey water. Each summer

the Garden Organic Information team receives manyenquiries on the best way to reuse bath and shower

water on the garden. Our advice is always to address

first the issues of storing water in the soil and collecting

rainwater. A bath full of clean looking water may seem

like a wasted resource, and maybe you did only use

environmentally sound detergents, but the water may still

be full of any number of pathogens collected on your skin

from all manner of places.

If you really must use it, do not store the water for any

longer than it takes to cool. Then, only water ornamental

areas and top fruit with it. At all costs avoid using it on

any food eaten raw, such as salad crops and soft fruit. Tobe able to store it or use it on more of your food crops,

it will need to be cleaned via a reedbed – and that is a

topic for another whole article.

If you want more information on small-scale reedbeds,

The Centre for Alternative Technology has an excellent

tips sheet available from their website www.cat.org.uk or

call 01654 705 950. We have a large reedbed at Garden

Organic Ryton and have a factsheet describing this; see

the members’ area of our website or call 024 7630 8215

for a free copy.

Carrie Pailthorpe

Advisor, Garden Organic Ryton

Water-wisegardening tips

Having enriched and mulched the beds, a drought has

hit, and your plants are starting to look thirsty. Even

if you have harvested all the rainwater for the last six

months, you will be aware that this is a finite resource.

How and when to use it? Here are some guidelines:

evening when evaporation is slower.

way to do it.

your plants for this valuable resource.

annual vegetables and flowers and any new plantingsover established perennials, lawns, and trees.

drying winds.

hot spring days.

between the plants.

water as the flowers open and as the pods are

swelling; leafy vegetables from two weeks before they

are to be cut; tomatoes should be watered twice

weekly from flowering; onions and leeks only needwatering as they are getting established; sweet corn

benefits most from water when the plant flowers.

Minimise digging and other soil cultivations The best place to store water is in the soil itself.

P h o t o s © S

a l l y S m i t h

gardening with water in mind

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