Michigan State University Extension
Ornamental Plants plus Version 3.0 - 00001634
11/12/99
Soil Moisture Problems
Soil moisture problems are usually related to soil
drainage. Poor drainage can be the result of the soil
type or the grade. Excessively drained soil fails to
retain moisture. Plants must tolerate dry conditions or
be given additional water.
Clay soils drain poorly. That is, once clay soils are
saturated, they retain moisture longer than other soil
types. Plant roots growing in clay can be injured by
excessive soil moisture during wet weather or by excessive
irrigation.
Soil modification in the planting hole will not have
long-term benefits. Water from the surrounding area will
more easily enter modified soil, flooding the root system.
Improving clay soils is difficult and usually not worth
the effort.
Sandy soils drain very well but retain little moisture for
plant growth. Adding organic matter will improve the
water-holding capacity of sands for a while, but the
organic matter will decompose over time and the soil will
again hold less moisture. As with clay, it may be easier
in the long run to select plants that will adapt to the
growing conditions on the site rather than try to change
them.
Drainage problems can be related to the grade or slope of
the site. Both dry and wet situations can occur. Plants
on the top of a berm or slope may suffer from dryness.
Water will soak into the soil at increasingly slower rates
as the surface layer becomes saturated. If water is
applied faster than the soil will absorb it, the excess
runs off the hill and does not benefit the plant.
Wet spots occur in low areas where water collects from
surrounding higher ground. A similar situation occurs
when a tree or shrub has a planting well around it. If
the surrounding lawn is watered too often, the water may
run into the planting well and drown the plant.
Wet areas can occur where downspouts from the eavestrough
empty. Often this is near the base of a plant, which is
injured by the excessive amounts of water. Plants growing
in mulched beds or planted in slight depressions will be
most seriously affected. Such injury usually occurs only
during prolonged wet weather or when the combination of
irrigation and rain is too much for the plant.
Dry areas often occur near buildings, particularly under
overhangs. Plants in these areas are often sheltered from
the rain and so experience very dry soil.
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to commercial products or trade names does not imply
endorsement by MSU Extension or bias against those not
mentioned. This information becomes public property upon
publication and may be printed verbatim with credit to MSU
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This file was generated from data base ZZ on 01/19/00.
Data base ZZ was last revised on 11/12/99.
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