Water Wise Irrigation - Waterwise South Africa

1. 1. Tips for watering the home garden 1. Tips for watering the home garden.
2. Nursery watering
3. Light and the impact it has on water • Watering of a garden may have some
utilization by the plant. recreational or therapeutic value to the
4. Humidity and pot plants homeowner but too much watering ends up
5. Water temperatures and pot plants just being a waste, especially in our dry
6. Effects of watering on plant growth and South African conditions. There is no reason
development. why existing landscapes can't be altered as
7. Innovative alternatives to watering trees and time goes by to incorporate water saving
large shrubs ideas. Landscaping to use less water must
8. When and how long to water become a culture within South Africa in
9. Watering plants immediately after planting order for the effects to be of lasting value.
10. Plants in clay containers Whether you are starting a new
11. Plants in plastic containers garden/landscape from scratch or have an
12. Watering hanging baskets existing garden you should constantly look at
13. Window boxes your options for saving water and where
14. Valuable plants during drought? possible improve on old non water saving
techniques.

2. • All gardens need to be watered at some time necessary. This is especially important for
or another, whether it is to initially plant or office blocks.
establish plants or to maintain plant growth • Check all water connections for leaks.
on an ongoing basis. It is therefore important • When planting a tree place a water pipe from
that the individual applying the water be the base of the tree roots to just above the
aware of these water saving ideas. Irrigation soil surface. Watering into this pipe will take
systems have a reputation of wasting water the water directly to the tree roots and
but through correct design and application prevent water wastage.
different combinations of irrigation systems • Flowers and vegetables need short, frequent
within a garden will actually assist in saving watering, while shrubs and trees need deeper
water. but less frequent watering.
• Don't start watering programs too early in the • In cool seasons plants need less water; in hot
spring. Plants will normally only flourish weather and when windy, all plants use more
after the first good rains. Rather spend time water.
improving soil and top dressings. • Where possible water trees separately and
• Switch off irrigation before puddling starts. consider digging a shallow trench around the
• Water dry spots individually, avoid wasting tree to catch and hold water.
water by watering a large area with the
sprinkler if the intention is just to water a 2. Nursery watering
single rose or a small section of grass.
• Where to water - (a) if the soil in the root Tips for saving water:
zone feels dry and crumbly, if it looks as
though the plant is starting to wilt. (b) Late • Never water paving. Use a broom to sweep
evening, early morning is best. (c) Avoid hard surfaces, not a hose.
mid-day irrigation which usually results in • Water at correct time of the day.
loss of water through evaporation. (d) Lawns • Different soil mixes require varied amounts
are best watered in the mornings to help of water.
prevent disease. • Different size containers need varied
• Sprinklers with course, low spray are best. amounts of watering.
Fine high pressure systems loose water when • Avoid over-watering.
the droplets atomize into the atmosphere. • Avoid using high pressure sprinklers on
This is often caused by too high water seedlings as they damage the young plants
pressure in the line. Make sure your selection and waste water. Water directly into bags
of irrigation nozzle suits your pressure. rather than generally watering the whole
• Water trees individually giving them a deep block of plants.
drink but less often.
• Water slowly to prevent runoff but long Hose pipe
enough to penetrate the root zone. By over
watering, water penetrates beyond the reach • On/Off fittings, in the form of ball valves or
of the roots, and excess water will run off trigger connections, save water.
and be wasted. Experiment to see how far • Maintenance and installation of the fitting
water penetrates within a given period. Then must be done correctly.
take a slither of soil from the watered area • Use a lance for reaching hanging baskets and
and check the soil moisture or use a moisture the back of beds.
meter (tensio meter). • Misters are useful for watering fern leaves.
• Drip irrigation is very effective when used on
vegetables, fruit trees and specimen trees. Watering can
• Automatic watering systems should be
altered according to season, time of day and • Seedlings.
amount of rain received unless it is • Turning the rose upwards for soft water
connected to an automated tensio meter and application.
or rain check. Never waste water by allowing • Window boxes.
the automatic system to water when not

3. • Using the point to get to each plant warms it is able to hold more water. When
individually. Don't use the rose as this wastes cold air is heated it dries out.
water. • Plants are grown at about 80% humidity
compared to the average building which
Container watering ranges from 35 to 65%, these plant leaves
become brittle and develop brown edges.
• Sump watering - sumps can be installed at This will be aggravated if:
the base of containers. They act as reservoirs
for water to be used later by the plant. The soil is allowed to dry out.
• The use of drip trays are recommended to There is air movement over the surface of
encourage collection of excess water. the leaf.
• Mixed planters - water plants separately and Direct sunlight through a window shines
according to their water requirement. on the leaves. (This will cook the plant.)
Use a wet bulb and a dry bulb
3. Light and the impact it has on water thermometer to calculate your humidity.
utilisation by the plant Refer to the table for the calculation.
• Light, water and food are the most basic SEE TABLE A BELOW
needs a plant requires to live. Plants will
photosynthesise food by using light energy in 5. Water temperatures and pot plants
direct proportion to the amount of light they
receive, provided the light does not cause • The temperature of water could have a
damage to the leaves through heat. Light is negative effect on a plant. Hot water will boil
also required to produce essential hormones the plant causing softening of the leaves and
for growth and flowering. later drying out. This often looks very similar
• If moderate amounts of light are available, to frost damage.
plants may not grow but will maintain a • The seriousness of the damage depends on
healthy, good looking, condition. Other the coverage over the plant. The plant could
plants merely survive as the light levels recover if only a small proportion of the
deplete. At even lower levels of light plant becomes damaged.
intensity the plant will begin to die. • Cold water is also harmful to plants. This is
because the indoor environment is often very
• Watering should be reduced as the light stable with regards to temperature and
intensity drops and the plant starts to grow sudden changes in temperature reduce the
slower. It is easy to over water plants in low water and nutrient absorption of the roots in
light causing more stress to the plants. the short term.
Common symptoms of over watering are • The plant responds as it would in a "drought
root and stem rot. "situation by dropping its leaves. Two
• Low light particularly in doors will cause the examples of plants and their responses to
plant to become etiolated (leggy). These water temperatures are tabled below.
plants are not strong and are very susceptible
to disease and pests. To combat this, interior Number of leaves dropped at
plantscapers keep plants very dry. This Plant
different irrigation water
regulates the plant growth. Keep in mind that Species
temperature
water should be gradually reduced.
2°C 10°C 20°C 30°C
4. Humidity and pot plants
Ficus
404 282 305 320
• Air conditioners often dry out the air making benjamina
it difficult for plants to grow well. The
Dracaena
amount of moisture in the air is referred to as 132 134 96 67
marginata
Humidity. This is the percentage of
maximum amount of water vapour the air
can hold at a given temperature. As air

4. 6. Effects of watering on plant growth The problems most commonly experienced
and development. are:
• For optimal growth, optimal watering is • Soil compaction does not allow water
required. Too much or too little will reduce penetration and results in restricted root
growth. growth and smaller trees.
• Over watering; Plants roots require oxygen • Erratic watering of trees also restricts root
as they are living and respire. Long periods and tree growth.
of saturated soil will suffocate the roots.
Secondary infections caused by bacteria are Innovative methods to try - for special trees
quick to move in and further damage the needing extra attention:
roots.
• Symptoms of over watering include: • Use a deep root irrigating lance that is
o Wilting foliage. pushed into the soil and waters deep down.
o Leaves turn pale and new growth is • Inserting pipes into the base of the tree hole
weak. before soil is put back. This allows for water
o Stem base is soft and spongy. to be applied directly to the roots.
o Strong pungent odor. • Drill holes into the compacted soil all around
o Excessive leaf loss. the tree drip line. Wetting granules and water
o Brown tips with yellow stripe on retention granules can also be
leaves. included into these holes.
o Young shoots appear shriveled and • Use soaker hose or leaky pipe for slow even
blackened. watering. It should be well hidden under the
o Roots appear dark and mushy. mulch. They can be coiled around the tree.
o Few or no flowers. • Harvest water using swales to direct water to
o Flowers buds develop brown spots. the tree. Trees planted in these hollows
o Plants are easily uprooted. should have good drainage. (Could drown
o The presence of fungal growth and the tree if very frequent rain is expected.)
fungus gnats or sciarid flies. • Drip grey water onto the tree - as in a forest
garden.
• Symptoms of under-watering include
o Leaf edges turn brown. Other good ideas for water efficiency:
o Flowers fall off.
o Stems show signs of wrinkles. • Where possible water trees separately and
o Leaves lose their shine and take on a consider digging a shallow trench filled with
blueish luster. mulch around the tree as wide as the drip line
o The growing medium shrinks away to catch and hold water.
from the side of the container. • Cut down on high nitrogen based fertilizers,
o Leaves become yellow or crispy and rather use fertilizers with high ratios of
suddenly. potassium (K) and phosphorus (P). This will
encourage plant cell walls to thicken
enabling them to cope better in drought
7. Innovative alternatives to watering
conditions.
trees and large shrubs • Light pruning helps plants cope during water
restrictions because of reduced transpiration
Most common watering practices include: from aerial parts.
• Erect tanks around the house to collect
• Irrigation systems. rainwater from roofs.
• Hand watering. • Apply mulches to soils and garden beds in
• Use of basins and mulches. order to reduce water loss.
• Aim to contain rainwater, rather than
allowing it to run off site. This can be done
by, altering the slope of the land, using
retaining walls, making berms and gabions or

5. by draining water into depressions where it watering will cause the fruit to be lacking in
can slowly seep back into the landscape. flavour and cause them to split.
• Avoid transplanting plants as this will induce
unnecessary stress. • Deciduous fruit trees should not be watered
in the winter to prevent early development
and frost damage, but as soon as the
blossoms start they need good watering to
lengthen the pollination period because this
keeps the blossoms on the tree as long as
possible. The longer the blossoming period
the more chance there will be for pollination
to occur. The tree will require large amounts
of initial water to moisten the soil profile all
the way down so don't be hasty in watering.
• Remember to water well after fertilising so
as to soak the fertiliser into the soil and to
• Established shrubs and hedges will rarely lessen the effect of fertiliser burns that may
need to be given additional water. In the accrue.
majority of years their roots will be extensive • During early spring watch new growth as the
enough to enable them to obtain all the fresh leaves are very sensitive to wind and
moisture they require from the soil. When heat wave damage. During these periods
they are first planted, however, a shortage of extra water will be needed. Remember to
moisture can easily lead to stunted growth, or water at night as day time watering
even death. contributes to the loss of large amounts of
• The amount of water these plants require will water due to evaporation.
depend upon the soil type, weed competition
and the weather conditions. Applying water 9. Watering plants immediately after
for 15 to 20 minutes as fast as the soil can planting
absorb it will be adequate for most situations.
Ideally you should aim at moistening the soil • When plants are placed in their growing
to a depth of about 150 mm. positions it will be beneficial to water them
in. You should aim to thoroughly wet the soil
8. When and how long to water around the roots, and moisten the leaves with
a fine spray. Applying water in this way will
• Fully established trees should be able to ensure that the plants have the correct
survive without any extra water in normal conditions for rapid establishment, and will
rain cycles. In extended dry periods good reduce the time they remain wilted. Water
long watering will need to be considered. should not be spared when planting as this
• Watering will depend on the soil type. Sandy first watering is the most important one.
soils don't hold water well and dry out • If you plant shrubs or hedges during late
quickly, whereas clay soils hold water well autumn or winter the soil will need extra
and need watering less frequently - they can water on the highveld because of the lack of
in fact hold too much water and become rain. If you find that the soil begins to dry out
water logged. Loam soils are ideal as they immediately after planting you should
have the right balance of water retention and irrigate the site. But don't overwater.
drainage. • When transplanting large trees use a product
• For more information refer to SOIL (2). like Kalpak which contains cytokinin, a
• The type of sprinkler used will affect the hormone to stimulate root growth. The
time that it takes to water a tree. Slow product is mixed with water and sprayed on
delivering drippers could take hours to water to the leaves and watered in the roots.
a section while a high pressure hose could • Remember to seal any wounds or tears
fill a trees water basin in seconds. occurred during planting.
• Fruit trees require watering to help fruit set
and form. Once they are well formed over

6. 10. Plants in clay containers • You may use watering sticks to gently water
the soil during periods of leave. They are
• Plants in clay containers can be checked for made of porous clay and water seeps through
water by lightly tapping the side of the to the plant.
container with a solid object, such as a cotton • Many pots have a built in sump under the
bobbin on a stick. A light ringing noise will pot. A sump is a collection area for water
tell you that the growing medium is dry, under the container this allows for extended
whereas a dull noise will tell you that there is periods between watering. Always inspect
moisture present. This method works best for the pipe into the sump with a dip stick to
loam based growing mediums. check that you do not over water the plant.
• Lifting the containers up will also give you Over watering will cause the water in the
an indication of their moisture content. Light sump to rot and will cause bad smells, this is
containers will contain less moisture than because the roots start to die due to the lack
heavy ones. of oxygen. Water will move back into the
• The third way of telling if these plants need soil medium when the soil dries. It is not
watering is to push your finger lightly into uncommon for some plants to adapt their
the soil. If your finger feels moist and the roots and dangle them into the water,
compost sticks to your finger, the soil provided there is still air available for the
probably contains sufficient moisture. But be respiration of the roots.
aware, frequent light watering may wet the
top portion of the pot, but leave the bottom 12. Watering hanging baskets
portion dry. When you water, therefore apply
enough to ensure that surplus water runs out • Hanging baskets can produce excellent
of the drainage holes. This ensures that the displays during the season, but their
entire root ball has received water. management is difficult because the limited
amount of growing medium available in the
11. Plants in plastic containers smaller area means that they dry out quickly
in hot weather. The correct watering of these
• It is very difficult to judge the moisture containers is critical if healthy growth is to
content of growing mediums in plastic be obtained.
containers. You cannot use the 'tapping' • The use of soil moisture granules help to
method as no distinct ringing noise is made, increase the water holding capacity of the
and it is also difficult to judge the moisture soil and are very valuable in these instances.
by lifting the containers. With this type of • During the early stages of establishment,
container the best method of checking the hanging baskets can be dipped into
moisture content is to press your finger into containers of clean water, and allowed to
the compost. soak until all the soil is wet. However, as
• When you first start to water plants in pots or growth proceeds and they are hung in their
other containers you may tend to either final positions, this often becomes
under, or over water them. With a little impracticable, and watering using cans or
experience you will soon learn whether your other special equipment becomes necessary.
plants need watering or not. In practice it is • You will need to water hanging baskets at
better to slightly under water than to allow least once per week during the season, and in
the soil to become waterlogged. hot periods this may be increased. You
• Never leave a plant standing in deep saucers should never allow the soil to dry out, as the
for a prolonged time as this will cause the plants can rapidly deteriorate, and may die.
roots of the plants to die because of the lack
of oxygen in the growing media. Tips
• Should you be going away and cannot do
your regular watering, use this as a very short • Fit a lance to the hose pipe for easy access
term solution and don't make the basin into the basket.
deeper than on tenth of the height of the • Put a pot plant under the basket to utilise any
container. dripping water.

7. 13. Window boxes can fitted with an upward facing rose, is used
with a continuous swinging movement. At no
• Window boxes are similar to hanging baskets time may puddles occur as this will cause the
in the sense that they have a relatively small seed to float away and be displaced. Dribbles
amount of growing medium for the plants to as the water starts and finishes will also
grow in. They tend to dry out quickly during disrupt the seed bed so start and finish the
hot weather, and need to be watered as often swinging movement off the side of the seed
as twice a week. In extreme conditions daily bed. Should the seed at any time dry out the
watering is required. plants will die so three hourly checks will
• Always ensure that the soil is completely need to be made in hot weather.
watered. It is best to use a watering can with • Bedding plants are shallow rooted, which
a rose fitted, when the plants are first means that they can dry out rapidly in hot
established, but the rose can be removed, weather. If the maximum floral display is
once establishment is complete. required you should water them during any
• Watering well in the evening, enables the dry or hot periods.
plants to absorb a good store of water • Always be on the lookout for drooping plants
overnight, light watering during the day which will be the sign that you should water.
could also be necessary for cooling, but the Mulching around the annuals is a great water
sun may evaporate much water before the saver as the evaporation from the surface is
plants can utilise it. cut down. Be careful not to swamp the
annuals with mulch as this will result in them
Tips rotting or make them vulnerable to fungal
attach. On small beds watering can be carried
• You should use a lance at the end of the hose out using watering cans, or hose pipes fitted
pipe with an on and off trigger for with a rose.
controlling the water. A rose will be
necessary with young delicate plants. 14. Valuable plants during drought?
• Remove the rose from your watering can
once the plants are well grown so that the • Try and rank the order of importance of the
stem of the can allows easier aiming of the plants in the garden that need water so that
water into the container. you do not lose the garden totally in the
• Always water each plant individually. You drought: Trees, ferns, shrubs, perennials,
must water the whole area. lawn, annuals and containers Answers: A
rule of thumb is leave the lawn and annuals
Watering bedding plants till last save the prized older plants which are
not easily replaced. During a drought only a
• Bedding plants are often grown in individual small amount of water will be available. It is
containers, or massed in seed trays or therefore important to use your available
directly from seed. water in accordance with the use zones,
• Plants grown in individual containers should created in your garden.
not normally have their roots damaged • Plants growing in shallow soil or exposed to
during planting, but those grown in trays can strong winds or bright sunlight, have to
sometimes suffer from accidental root loss. compete for water with the roots of other
Root loss will require extra watering to plants, and this needs to be remembered
prevent damage to the plant. during dry times.
• Immediately following planting you should • The following landscape plants (ones most
make sure that all the plants are watered usually watered) suffer most without
thoroughly, so as to reduce the risk of wilting irrigation. Learn the symptoms of drought
- this is especially important for any plants stress so you are able to recognise plants that
with damaged roots. Watering should be might be in trouble.
continued every day until the plants are • Azaleas, evergreen - established landscape
established. plants, use a wetting agent to aid water
• Bedding plants grown from seed need more penetration. If new foliage droops, irrigate
sensitive watering techniques. A watering fast.

8. • Camellias - Young ones will need some Foliage will perk up if you give roots
water. Watch for wilting new growth. adequate water soon enough.
• Citrus - Mature trees are surprisingly tough, • Roses - Young stems will need water. Less
they can survive on half their normal water water will mean fewer blooms. Leave seed
requirements. Try spacing watering four to heads on to slow growth. Remove suckers,
six weeks apart. Watch for wilting, but don't otherwise prune until winter.
discolouration and leaf drop - in that order - • Star Jasmine As a ground cover, this is
as symptoms of trouble. Apply water slowly inexpensive to replace if it dries. Prune large
to the root zone with a soaker hose or in a vines to reduce leaf surface, water when you
basin until the soil is wet to a depth of about can.
two feet deep. Trimming on citrus is to be
beneficial it does not stimulate fast growth. TABLE A
• English Holly (Ilex aquifolium) - Probably
Relative Humidity At Given Dry Bulb
the most sensitive of the hollies, it will need
Temperatures and Given Wet Bulb
monthly watering.
Temperatures (Referenced from IPSA
• What are the most common symptoms of
training Manual)
water stress in plants? When do these
symptoms become fatal? Dry bulb temperatures in top row (°C) Wet
• Ferns - Most low growing types respond to bulb temperatures in all lower rows (°C)
drought by browning, then going dormant.
They come back with water. Tree ferns need Relative
more help. Try watering severely stressed 16 18 21 24 27
Humidity
ones with just two litres of water per plant,
poured directly onto the crown. (Water runs 15 7 9 10 12 10
down the trunk's sides and gets into the
plant's system because the trunk is an aerial 7 8 9.5 12 13 20
root). 8 10 12 13 16 30
• Fuchias - In mild climates, older plants with
woody trunks can go a summer without 9 11 13 15 17 40
wilting. Even if they lose their leaves and go
dormant, they often come back. Young 11 13 15 17 19.5 50
fuchsias with succulent stems need water.
• Gardenias - Big flowered types, such as 12 14 16 18 21 60
'Mystery' need water regularly. Fertilise only 13 15 17 20 22 70
if you can water as usual.
• Hydrangeas - Leaves may wilt and drop, but 14 16 19 21 24 80
stems should stay green and recover when
watered. If some of the stems dry and 14.5 17 20 23 26 90
shrivel, the plant needs water.
• Japanese maple (Acer palmatum) - Prolonged 16 18 21 24 27 100
drought can stress even large unnamed
seedling types. If you have the water, give
them one deep watering in late spring.
Smaller grafted varieties (usually the ones
with finely cut foliate) are much more
susceptible to drought damage. They may
need monthly watering.
• Podocarpus - When drought stressed, it first
loses leaves, then twiglets and finally
branches. When you see stress, water just
enough to prevent worsening.
• Rhododendrons - When they need water,
their leaves hang and new growth wilts.