Why you should revegetate your leach field
By Suzy Crowe, Master Gardener
Whether you have an existing
leach field or are constructing a new one, leaving the leach field
bare of vegetation can immediately can lead to big problems. Planting
a leach field helps the system to function properly, improves the
look of a large open area, and controls noxious weeds.
Understanding how a leach
field operates helps you determine what, how and when to plant.
A leach field is a series of perforated pipes lying in a bed of
gravel buried 15 to 18 inches deep. All household drains lead to
a purifying tank. The waste is gravity fed through these drainage
pipes and seeps into the leach field where the effluent is purified
by the soil. If the soil in the field is clay or compacted, your
pipes are clogged or your system is just not working properly, the
effluent may not drain as efficiently. Revegetating the field with
native grasses and wildflowers can help the system to function properly
by pulling moisture out of the soil through evapotranspiration.
When it comes to planting on a leach field, the effluent should
not be a problem if the system is working properly. Any bacterial
or viral contamination should be percolated down into the soil.
If the effluent isn't percolating properly it may rise to the surface
contaminating the soil. However, it is hard to determine if your
system is functioning properly.
Leach field soil may
also be highly alkaline not only because of the effluent but also
because many household cleaning products are highly alkaline. Since
all drains lead to the leach field the soil tends to have a high
PH level. Have soil tests done before planting to determine if their
will be problems with your soil. The PH level may also indicate
if your system is working properly.
So what plants are the
right plants for a leach field? Low maintenance, low water, shallow
rooted plants that grow in a variety of soil types (salt-tolerant)
are most suited to this site. Trees and shrubs may clog the drainage
pipes and cause your system to malfunction. Vegetables, although
tempting to plant since leach fields get a large amount of sun,
are a poor choice due to the percolation issues discussed above.
A raised bed of veggies is also not a good choice. A raised bed
eliminates the problem of questionable soil, but inhibits the evapotranspiration
of moisture from the field that helps the septic system function
properly. Standard perennials might not be a bad choice, but may
be more high maintenance than you want. As well, leach fields are
generally located in a place on your property that is tucked away
and your perennials not enjoyed.
The best choice is a
native grass and wildflower mix. They are best suited to the disturbed
soil and lack of water. They take less maintenance and their rapid
spread can cover a large leach field in no time. Seeds should be
sown in the fall. Make sure you remove all existing weeds before
sowing so you start with a clean slate. The soil should be loosened
a few inches down. Sow the seeds by hand. Mixing the seeds with
a little sand helps distribute them evenly. Cover the seeds with
the soil you tilled. Avoid bringing soil in from another location
on your property because it may come with some new weed seeds and
new problems. Covering the planting with a little mulch helps water
retention and keeps the wildlife out. The following spring when
your seeds germinate, monitor your new wildflower meadow for weeds
as their seeds may take a season to germinate.
Controlling a weed problem
before it happens is easier than eradicating a weed problem after
you have one. The choice is yours. Put the time and effort into
it from the get go and avoid problems down the road. I learned the
hard way. I installed a new septic system and vegetated it the following
fall only to find that when the seeds germinated the following spring,
so too did all the weed seeds that had lain dormant a full season.
One sore back later, the existing weeds were gone before they went
to seed. But had I vegetated my leach field the first season, I
would've saved my back. The moral: save a back, kill a weed.
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