WET FEET IS THE NUMBER 1.
PLANT
KILLER.
Almost 70% of all plant deaths in
Melbourne, within the first few months after planting, are caused by wet feet. Chris &
Marie's Plant
Farms have a garden inspection service which visits and assists customers experiencing
difficulties with establishing our plants. We
have visited hundreds of customers and have
discovered that 7 out of every 10 problems are caused by wet feet. |
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WHAT IS WET FEET?
A lack of oxygen in the soil around the root zone of plants occurs when the soil is saturated
with water for more than a day. Organic matter starts to decompose and uses
up all of the available oxygen thus the plants die due to lack of oxygen being available for
uptake through their roots. Wet feet can be
detected by saturated soil containing lots of
organic matter, a septic or anaerobic smell and discoloured or dying plant roots. |
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IN WHAT SITUATIONS IS WET FEET
COMMONLY FOUND?
Heavy clay - Where plants are planted in heavy clay with a lack of air
porosity.
Particularly where there is a lack of topsoil and the planting hole is dug into very dense
clay sub soil.
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No Drainage - In
courtyard areas, around
driveways, concrete pathways or retaining walls many garden beds have no provision for water
to drain away from beneath the ground. Most shrubs and flowers require a well- drained root
zone to a depth of 12 " and small ornamental trees require a well - drained root zone to
a depth of 18 "-24 ". Wet feet is likely to occur where garden beds have been
constructed and surrounded by hard landscaping with no provision for subterranean drainage of
the root zone.
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Planting in 3 way,4 way or
organic soil
mixes - Many garden soil mixes are made from a mixture of very fine sand and rapidly
decomposing organic matter. Within a few weeks these soils become waterlogged and the organic
matter decomposes causing the soil to compact into a very heavy wet anaerobic soil. These
soils can cause wet feet even when the garden beds are otherwise well drained. |
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Excessive watering of
garden beds - Garden beds that have automatic watering systems and garden beds that
are down slope from automatic watering systems are often watered too frequently, particularly
at times when evaporation rates are low. Water is a valuable commodity and far more plants die
from over watering than from under watering. It is best to water manually where possible and
use your automatic watering system when on holidays.
An occasional long deep soak is generally better than watering all the time. Observe when your
plants require water or when the soil is dry underneath and water at this time. |
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Laying Instant Turf
When instant turf is layed it requires constant watering for several weeks until it takes
root. This can cause surrounding garden beds to become water logged.
When making a new landscape with instant turf establish the turf before making and planting
the garden beds. If you are establishing turf with established garden beds consider hand
watering the turf to keep it wet without water logging the surrounding garden beds. |
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Digging a Hole for a Plant
and Throwing
Away the Parent Soil.
Often when people dig a hole for a plant and
discover the soil in the hole is very hard or heavy clay they remove the original or parent
soil from the hole and plant their tree or plant with some potting mix, compost or garden mix
that is softer and more porous with a lower density than the original parent soil,this is a
recipe for disaster! The flowing of water takes the course of least resistance and the hole
fills with water, the organic matter in the new soil will decompose and the plant will get wet
feet. When digging a hole in heavy or dense soil replant using 80% parent soil and only 20%
soil additive. The soil additive should not contain animal manure or fast decomposing organic
matter, instead it should only contain washed river sand, mineral gypsum or slow decomposing
organic matter such as composted pine bark. Use only slow release fertiliser such as
Devotion Time Release fertiliser, provision for drainage should be made where necessary. |
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PLANTS AT RISK OF WET FEET
Many plants are affected by wet feet but from analyzing our customers complaints and problems
here are some of the most at risk plants. If you are planting these types of plants be
diligent to avoid wet feet. |
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Plants at risk of wet feet
include:
Weeping Cherries, Weeping & upright Silver Birch, Pittosporums, Mop Tops, Gardenias, Rhododendrons, Proteas, Azaleas, Standard Ficus, Standard Blue
Potato Vines,BoxOz® Lonicera, English
Box, Weeping & upright Japanese Maples, Citrus, Fruit Trees, Standard Roses, Lavender,
Silver Bush, Powton® Sapphire Dragons and Myrtus Luma. |
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All very large advanced plants are
more at risk of wet feet as they have a large root mass and require a deeper hole which means
that the bottom of the root mass is more likely to be planted in poorly drained sub soil
therefore exposing a larger more vulnerable plant to wet feet. |
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PLANTS AT LOW RISK OF WET
FEET
All plants can be adversely affected by heavy soil and wet feet but these plants seldom have
wet feet problems or generate customer complaints. |
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Plants at low
risk of wet feet include :
Celtic Cascade® Salix
caprea 'Pendula', Evergreen Cascade® Alder, Toorak 'Gum Tree' Alder, Dwarf Nandina, Mondo Grass,
Bongo Borders® Liriope, Photinia Robusta, Box
Leaved Privet, Carpet Roses, Rock Roses, Seaside Daisy, Castlewellan Gold Cypress,
Neighbours-Be-Gone®Trees, Acmena
smithii
, Chinese Elms,
Plane Trees, Ash Trees, Hydrangeas, Viburnum, Wiegelia, Golden Diosma, Callistemon,
Melaleucas, Tea Trees
and Eucalyptus. |
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COMMON WET FEET MYTHS
There are a number of popular myths about
wet feet that defy the laws of physics. |
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1. |
I
have sloping land so I cant get wet feet. People on sloping land are actually more likely
to get wet feet as water flows downhill. Poorly drained garden beds and planting holes will flood
more quickly and more often on sloping land. People with heavy or non-porous soil on sloping land
who dig planting holes are more at risk of wet feet than people who dig planting holes in
flatter land. |
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2. |
I
will put pebbles,gravel,bricks,clay breaker, compost in the bottom of the hole to make the water
go away. If you dig a hole in impervious clay the only thing that will make the water
flow away is a drainage channel or a pipe. If you fill your bath with water the way to empty it is
by pulling the plug out. |
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3. |
If I
dig a really big hole the water will go away. Theoretically this may work but you may
have to dig to China! When digging in impervious or poorly drained clay soils a big hole will
simply hold more water. The only thing that will drain a really big hole is a drainage channel or
an agricultural pipe. |
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4. |
I
just won't water my plants. Not watering as an alternative to providing good
drainage doesn't work in Melbourne as Melbourne has prolonged periods of rain that will saturate
any poorly drained area. |
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IDENTIFYING A POTENTIAL WET
FEET SITUATION
If you have an area where you suspect you may have wet feet, dig a large hole to the depth
that you intend to plant your plant to, if you are planting an advanced plant you will need to
dig a very deep hole. Fill the hole with water several times,the hole should drain within
20-30 minutes after the second filling with water, if the hole doesn't drain you have a
potential wet feet problem. |
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PREVENTION OF WET FEET
Don't ever use 3 way, 4 way or organic soil mixes that contain a mixture of fine sand and
animal manures. You can get wet feet even if your garden beds are well drained using these
products. |
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If you have identified a poorly
drained area you can: |
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2. |
Ask our
nursery staff for assistance to help you select wet feet tolerant plants. |
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3. |
Provide
drainage using washed river sand, mineral gypsum at the rate of 3kg per m 2 and composted pine
bark throughout your soil to improve porosity, don't use more than 20% volume additive to
the parent soil, we recommend Devotion Planting Mix For Wet
Feet, Heavy & Clay Soils.
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THREE GOOD WAYS OF
PROVIDING
DRAINAGE |
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1. |
Cultivate a circle approx. 4ft wide x 1ft deep and add
several wheel barrows full of loamy soil. Mix
this with your parent soil and create a
mound. Many
trees such as Silver Birch, Elm, Pine and Oak will die if planted
in water but will quite happily grow their roots down into the water. |
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2. |
Dig a hole 18 inches to 24 inches deep x 4ft across then dig a trench and lay
agricultural pipe to connect with the nearest storm water pipe. Put a gravel bed in the bottom of
the hole so that the water drains to the storm water pipe.
One agricultural pipe if laid
strategically through the garden can drain many trees and shrubs. Then fill the hole with a
mixture of 80% parent soil and 20% washed river sand, composted pine bark and 3kg/m 2 of mineral
gypsum. Sometimes the stormwater pipes are buried near the soil surface and an agricultural pipe
connected to the stormwater pipe will not provide drainage for the entire root zone of the plants
being planted. If this is the case the garden bed can be mounded or raised to provide suitable
depth of soil for the agricultural pipes.
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3. |
If you are
planting into poorly drained soil on sloping land you can drain tree root zones without connecting
to a storm water pipe by digging a large hole with a narrow trench running downslope from the
hole.
Then fill the bottom of the hole and
trench with gravel. Fill the balance of the hole and trench with a mixture of 80% parent soil and
20% washed river sand, composted pine bark and 3kg/m 2 of mineral gypsum. Plant your new tree or
shrub in the top of the hole. Water will now drain from the base of the hole through the gravel in
the bottom of the trench. |
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