By Jay White
Four years ago, I went to war!
Weeds in my vegetable garden and flower beds were
sucking all of the joy out of my gardening experience.
So, in 2006 I declared war on my weeds.
started my current garden, I decided that I would do
everything possible to be an organic grower. At that
time, I did not fully appreciate how difficult weed
control can be for the organic grower. Within three
months of tilling up a portion of an old coastal field
of Bermuda grass in Washington County and planting my
first fall garden, I was already losing the war to the
weeds. Out of frustration, I began to research organic
weed-control methods. Due to this research and much
experimentation, I have now developed an integrated weed
control program that has greatly reduced the amount of
time I spend bent over in my gardens. My integrated weed
control regime consists of “Four P’s”: preparation,
pre-emergent tools, post-emergent tools and persistence.
Organic growers do not have
access to many herbicides that are as effective as
something like RoundUp, so it is important to do
everything possible to kill or remove as many weeds as
possible before any other organic weed-control methods
are applied. Proper bed preparation is the critical
first part of an integrated organic weed-control
program. The following activities are effective organic
Solarization — Solarization is a
process in which clear plastic is laid over an area of
weed infestation. The clear plastic allows the sun’s
radiation to raise the temperature in the air gap to a
level that will “cook” any seedlings that dare to
emerge. When I get ready to prepare a new bed, I mow the
vegetation very close to the ground and then water it
thoroughly. Then I spread a sheet of 4- or 6-mil
polyethylene over the area. Once this is down, I secure
it with either soil, lumber or old bricks. It is
important to get a good seal all around the plastic. You
don’t want any of the hot air escaping. Then, depending
on the season, I walk away for three to six months and
let the sun do the rest.
Solarization has been
very effective for me. Once I remove the plastic there
is nothing growing. Nothing! All that is left is a bunch
of dried brown plant material. I till this into the soil
and the new bed is ready for planting and/or other
Smothering kills weeds by depriving them of both light
and water. The process I use for smothering is very
similar to the solarization process. Before I lay down
my smothering material I mow, chop or hoe the existing
weeds down to the ground. Smothering will work fine
without mowing if your smothering material is heavy
enough to push and hold the existing plants down.
I have used many different things as smothering
agents. Any opaque material will work, but my favorite
is plywood or HardiePlank. Both of these materials cover
a large area and weigh enough that they will not be
easily blow away. Tarps and black plastic are effective
if you take the time to properly anchor them. Wind is a
real enemy of these two. No matter how well I anchor
them, the wind always seems to find a way to uncover
everything I have tried to cover up.
also an effective smothering agent. Not only does it
suppress weeds, it breaks down and becomes additional
organic material. Newspaper is thin and fragile,
especially when wet. Because of its light weight, it is
difficult to keep in place. I only recommend using
newspaper in combination with mulch or in a small area
that has some protection from the wind.
using newspaper, I lay down about eight overlapping
layers. I use newspaper and hay in the walk paths of my
row garden. I re-apply this treatment every spring and
fall. My row garden really is in the middle of an old
coastal field and this combination of hay and newspaper
does a very good job of keeping the weeds in my paths at
Once a bed
has been sterilized through either solarization or
smothering methods, it is time to stop the weed seeds
that survived from germinating. Mulch and corn gluten
meal are two of the most common pre-emergent
weed-control weapons available.
Mulch is the organic gardener’s manna. In addition to
providing pre-emergent control, mulch conserves water by
reducing evaporation and runoff. It also keeps roots
cool in the summer and warm in the winter. On top of all
of this, mulch provides organic material to the soil as
it breaks down. In my opinion, mulch is the premier,
pre-emergent weapon in the organic gardener’s arsenal.
Mulch works by depriving weed seeds of the light
they need to germinate. I have done some experiments in
my own beds and I have found that a 6” layer of hardwood
mulch yields the best control. When I get ready to mulch
a new bed, I always put down newspaper first. The
newspaper adds one more layer of light suppression that
I have found to be very effective. When mulching a
pre-existing bed, I simply add more mulch on top of the
old, existing mulch.
I get my hardwood mulch from
the Brenham landfill. Most municipalities sell mulch and
compost. If you have a truck, this is the way to go. I
get my mulch for a penny a pound. That is just $12 for
one cubic yard of mulch (approximately 1,200 pounds
depending on moisture content). At that price there is
no reason not to mulch.
Even though I now use
hardwood mulch exclusively in my flower beds, there are
many other products out there that will provide the same
level of suppression. In previous gardens I have used
cedar bark, pine bark, pine needles, grass clippings and
hay. There are countless other varieties available as
well. Experiment with different things and you will
quickly discover what works best for you.
Mulching is not something that can be done only once.
Mulch is (usually, not always) an organic material. As
such, it breaks down and turns into compost. Because of
this, it becomes a great landing spot for airborne weed
seeds. To reduce this, I mulch everything twice a year.
Corn Gluten Meal — Corn Gluten Meal (CGM) is
a by-product of the corn milling process that has
certain properties that make it effective as a
pre-emergent herbicide. CGM contains proteins that
inhibit root growth in newly germinated plants. There
really is no downside to this organic weed control
weapon. It is completely non-toxic (you could eat it, if
you needed to), it controls weeds and it acts as a
fertilizer. An application of CGM is the organic
equivalent of a formulated 10-0-0 fertilizer found at
Recent experiments at Texas A&M
by Joe Masabni, Ph.D., Extension vegetable specialist,
and Patrick Lilliard, Extension specialist, have shown
that CGM is a very effective pre-emergent when applied
at the proper rate and at the proper time.
their experiment, four 8’ x 8’ beds were prepared by
manual means. Each bed was sub-divided into four 2’ x 2’
beds. These sub-beds were randomized and each contained
one control block. The other 3 blocks received one, two
or three applications of CGM at a rate of 5.12 oz/block.
This is equivalent to a field application rate of 80
lbs/1,000 sq. ft. At the end of the experiment, all
plant material was removed at soil level and weighed and
According to this experiment, a single
application of CGM reduced broadleaf weeds from 9.69 g
in the control block to 1.2 g in the other blocks. This
is equivalent to an 88 percent reduction. A single
application of CGM was not very effective against
grasses. Grass control required a second application two
weeks after the first, and a third application two weeks
after the second. By applying CGM three times over a
five-week period, grasses were reduced from 4.91 g to
0.29 g, or a 94 percent reduction. Broadleaf weeds
treated over the five week period were reduced even
further to 0.07 g or a 99 percent reduction.
this experiment shows, CGM is an effective pre-emergent
herbicide in a homeowner’s garden. CGM has gained much
popularity and is easy to find at most garden centers.
Most box stores and nurseries also carry it.
is important to note that CGM is only effective as a
pre-emergent. Once weeds have germinated (even at the
seedling stage) or became established, CGM has no
measureable affect as an herbicide. In fact, the
nitrogen in the product can actually accelerate the
growth of the weeds.
Dense plantings —
Sometimes we cause our own problems. Traditional
planting methods have us tilling up long straight rows
with walk paths between them. The war of the weeds is
usually lost in the pathways between the rows. One way
to reduce this issue is to change the way you raise a
garden. Lay out your beds in squares and plant your
crops as close together as you can without harming
production. Dense plantings choke out weeds by limiting
the light available to them. Close plantings in square
beds provide the same square footage of production with
gardeners I know hate to pull weeds. That is why an
integrated program is so important. Persistently
applying the “Four P’s” will greatly reduce the amount
of weeds that require manual removal.
— I have two very different vegetable gardens at my
house. One is a traditional row garden and the other is
a raised-bed garden. Hand weeding of the row garden is
not practical or effective; there are just too many
weeds. On the other hand, my raised-bed garden was
designed and built with the “Four P’s” of weed control
in mind. Because of this, there are few enough weeds
there that weeding by hand is an effective tool.
When pulling weeds, strive to remove them before they
set seed. An old garden adage is, “One year of seeding
equals seven years of weeding.” So, pull weeds when they
are young and never ever let them set seeds. If weeds
are pulled in their immature form, they can go directly
into the compost bin with no worries.
increase the effectiveness of my hand weeding, I always
use various tools to assist me. A garden trowel, a large
screwdriver and a meat fork are great tools that help me
remove weeds, roots and all.
Vinegar (or acetic acid) is an effective post-emergent
herbicide that works by removing the waxy covering from
plants. Removing the cuticle from the plants allows them
to “transpire” themselves to death. Common household
vinegar (5 percent acetic acid) can be effective
(especially if combined with a little dish soap and
little rubbing alcohol), but real killing power resides
in the more concentrated forms found at garden centers.
Acetic acid is available in concentrations up to 20
percent. Concentrated acetic acid is quite effective on
a wide range of both grassy and broadleaf weeds. I have
seen dandelions and crabgrass begin to wither 30 minutes
after the initial application. Vinegar is best when
applied to young plants. Established weeds may need a
second or third application to finally kill them.
Be careful when applying vinegar. Overspray can kill
things you don’t want to die. I use a spray bottle and a
shield when spraying close to my desirable plants. If
you want to spray a wide area, then a pump sprayer works
Hoeing — A sharp garden hoe is
an effective post-emergent weed control agent. Hoeing is
much faster and less physically demanding than hand
weeding. A good sharp hoe can quickly clean up a lot of
space. I use the hoe frequently in my row garden. Hoes
are not effective against plants with a deep tap root.
Wild carrot and dandelion are particularly noxious weeds
with deep tap roots. Chopping these off at the surface
only slows their growth and they are bound to return.
Burning — My favorite organic post-emergent
weed control weapon is fire! I use a small hand held
propane torch to scorch weeds to death. You do not have
to “burn the plant up” for fire to be effective. I
simply scorch the plant by running the flame up and down
its length until there is a noticeable change in its
structure. This is usually enough to kill it all the way
down to the roots. One word of caution, some desirable
plants are very sensitive to high heat, so avoid burning
weeds that are too close to the vegetables or flowers.
Boiling water — I know several people that
swear that boiling water is a great weed killer. The
heat from the boiling water is supposed to kill the
weeds. I have seen some limited success when applying
boiling water to young plants. Unfortunately, 212
degrees is just not hot enough to kill most established
accepted the fact that there is no such thing as a
weed-free garden. I use all of the methods described in
this article and I still have weeds. However, I have
much fewer weeds today than I did four years ago.
The “Four P” approach to organic weed control has
reduced my weed populations to the point that I no
longer consider them my single biggest problem.
Through the persistent use of preparation and
pre-emergent and post-emergent tools I am slowly winning
the war of the weeds. I have now had enough success with
the “Four P’s” to believe that if I just stick to it, I
might actually get to fully enjoy my garden as the years
Jay White is a full time computer
specialist for the M.D. Anderson Cancer Center in
Houston, Texas, and he is completing an M.S. in
Horticulture at Texas A&M. In his spare time he gardens
and maintains “The Masters of Horticulture” blog at