Weed control without chemicals

Farming without weed problems is possible and can be done with no chemicals at all on many farms.

It may seem that good weed control can only be achieved with a massive amount of weedicide, but many farmers and graziers achieve excellent weed control without herbicide.

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The key is to change the balance such that your crops get more support, and the weeds get less.

What it takes will vary from one farm to another and from one farmer to another and from one season to another.

However there are some basic points that must be kept in mind:

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Once you have answered the question: "Why is there a space right here that this weed has managed to take over?" you can prevent those weeds coming back and stop other weeds from taking over similar spots.

"Crop" means more than plant crops: "Crop" on this website refers to anything you grow or manage that has some benefit that can be harvested in some way. "Crop" includes pasture, animal crops (such as milk, wool and meat) plus what are more commonly called crops such as corn, citrus or carrots, barley, broccoli or bananas
Any ground that is not presently 100% covered with actively-growing plants is ripe for a weed coming from the farm (including from seeds right there) or from outside. This is where Ground cover is a huge benefit.

The fewer spaces your plants leave, the fewer spaces weeds can take up. However, if you cannot maintain full ground cover of actively-growing plants year-round, then the next best form of ground cover is Litter.

This is where perennial plants really come to the fore. Because they maintain a high level of ground cover throughout the year, they leave few spaces for weeds to colonize.

In the absence of suitable perennials, or when you are resowing a field, choose a single variety or a mix of crop or pasture plants that covers the ground quickly. Plants that cover ground quickly snare space, light, moisture and nutrients as well as becoming stronger and more able to compete.

Generally, weeds are more of a problem when your crop is having difficulty. When there is plenty of sun, water, nutrients and no limiting or damaging factors, weeds are not as much of a problem as when your crop is not performing optimally.

This is because weeds are better adapted than desirable plants (crops and pastures) are to almost any difficulty.

Most crop and pasture plants are fussy and less capable in any but ideal conditions.

Pioneer plants such as weeds are usually well adapted to hard soils and to soils low in moisture, nutrients or in any other way below ideal. If you let your soil deteriorate, you take the advantage from your chosen plants and give it to the weeds.

Perennials, annuals, biennials
ANNUAL plants complete their life cycle in a year or less, starting from seed and producing another generation of seeds before dying.
BIENNIAL plants take more than one year but not always less than two years to complete their life cycle. The first year is often spent establishing and the second and later years are spent producing seeds. The plant generally dies after this.
PERENNIAL plants continue to live from one year to the next, often producing seeds each year.
Weed control is particularly important with perennial weeds because as well as weed seeds, you will have weed plants that may continue to set seed for years.

In theory, it is easier to eliminate annual and biennial weeds (than perennial ones) because they can be beaten by eliminating the seed phase. If you stop them seeding, there will be no weeds once the seed bank in the soil is exhausted. The existing plants will die after one or a few years and if they are not replaced, that weed problem ends.

Plants have few opportunities to move. The best opportunity to move or spread is when they produce seeds and they have many mechanisms for getting seeds to move.

Some plants have ways to spread other than through seeds: Because plants have limited opportunities to move, this is often the easiest point to protect yourself from weed spread.

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The points where you can beat weeds are: If you can beat the weed at any one or ideally at every one of these stages, you will have few weeds and weed problems.

Any weed infestation begins with at least a single seed or any other part of a plant that is capable of developing into a full plant. If you can beat it when it is a seed, a seedling or before it has a chance to flower, you will only have a brief problem with it. If you allow it to set seed, it can turn into a major problem.

Remember that what matters is the relationships between things rather than the things themselves. If you can work out where the relationships fall down, you will find it easier to resolve the problem than if you focus on any single thing.

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This table shows some
Weed characteristic What these characteristics may mean Approach that may assist you against the weed
Large numbers of seeds Poor seedling establishment
Poor seedling survival
Low germination rates
Make conditions (particularly competition) tough at germination and soon after
No bare ground around seeding and germination
Seedheads break off with seeds attached An effective method of dispersal with built-in insurance: If one of the seeds on the seedhead germinates but does not survive, there are several others that may when conditions are more favorable. Use windbreaks to confine seeds to specific areas
Note: A windbreak need not be particularly tall, and it need not be permanent. It could just be a tall crop, such as corn (maize), to catch the seedheads and prevent them spreading
Prickles on leaves or stems The weed would be attractive to stock otherwise Allow pasture to grow tall when the weed is starting to grow. The competition will beat some of the weeds. Others may survive by switching to upright growth and this usually means fewer prickles plus the weed will be softer and more palatable. A hard graze at an appropriate stage may get rid of it
Rosette at base Weed is trying to commandeer nutrient, light and water, most likely for next year when it will seed Vigorous crop or pasture may outcompete.
Make sure there are no bare patches
Grow a broad-leafed crop every few years
Weed is tall compared to crop The weed gets the light and shades the crop Grow a taller crop, such as an older variety
Weed grows from a crown or other underground store Base of plant is providing nutrient to kickstart the aerial part Exhaust reserves by slashing before any stem has returned the nutrient it took to grow it.
For example, if you slash blackberries before they get to about 1 m high, there is a good chance you will exhaust them, although it will take a few slashings
Remains after hard grazing
Survives hard grazing
Unattractive to stock May need to graze the field hard to make the weeds stand out and then remove weeds individually.
You may be able to make the weed more attractive by spraying it with molasses or by providing some high protein feed such as lupins so animals can digest it
Weed is able to get from a germinating seed to producing seed quicker than the crop is Weed has quick lifecycle so it can reproduce even in a short season Consider slashing the crop as a green manure or using it for grazing, silage or hay making before the weed gets to seed.
Then plant an out-of-season crop (a summer crop if the weed is in a winter crop and a winter crop if the weed is in a summer crop) and prepare the seedbed before any more of the weeds get to seed.
Weed is very vigorous A tough competitor that needs an even tougher crop Pick a suitable crop that can grow vigorously, preferably beating the weed at its own game.
For example, a vigorous variety of oats will beat most weeds or at least give them a run for their money. You may be able to take the weed out by grazing or by cutting the oats for hay.
Many oat varieties are suitable for grazing and regrowing to regraze. So, if you let the oats regrow and conditions are right you'll have a second chance at beating the weed by grazing or by cutting the oats for hay. Then it might be time to sow a summer crop and have a third go at beating the weed.
The weed looks and behaves in a similar way to your crop The weed possibly evolved in a cropping system similar to yours You will need to fine tune your management or find some particular weakness in the weed or strength in your crop.
For example, if you grow wheat or a similar winter crop and you have a problem with wild oats, you may have to delay sowing until the wild oats germinate. At this point, grazing, tillage or sowing the crop may kill a lot of wild oats.
You could also choose a tall variety of wheat that can outgrow the oats.
However, the best approach is probably to change crops and beat it with a suitable competitive crop that doesn't match the weed's patterns of growth.
Weed has uses in other places Weed may be an escaper from another farming or gardening situation and thus has had a positive value there, rather than being considered a weed Take advantage of the uses it has in other farming or gardening situations by turning the weed into a benefit:
  • Capeweed (Arctotheca calendula) is a very productive pasture plant and many a farmer in Western Australia would be out of business without it. But it can give plenty of problems if you don't manage it well.
  • If you are willing to run goats, many thistles and woody weeds (blackberry, briar etc) make good grazing or browsing. Some goat farmers are willing to agist their animals on your property.

A suitable next step might be:
Take one weed and apply some of the principles in the table above.

Pick a weed that matches well with one or more of the characteristics in the left column and check whether the middle column fits that particular weed in that situation on your farm.

If it does, then some of the approaches in the right-hand column might work for you.

If you are looking at a printed version of this page and you would like to visit it on the internet and get a stack of other info that may assist you, the full web address is

Related info:

Beat pests by using advantage

Learning from pests


Green manures in orchards and vineyards

Chicken tractor


Non-inversion tillage as a herbicide

Do weeds come to heal the soil?

Selective grazing

SWOT analysis to boost profit

Using SWOT to beat a major weed

Understanding the causes of weed problems

Choosing a farming course and teacher

Ground cover

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Farming without weed problems is possible and can be done with no chemicals at all on many farms. It may seem it can only be achieved with a massive amount of chemicals, but many farmers and graziers achieve it.

The key is to change the balance such that your crops get more support, and the weeds get less.

What it takes will vary from one farm to another and one farmer to another and one season to another.


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This page was updated on December 27, 2007