How To Use Weedkillers

Weedkillers are not cheap and to get the very best from them, they need to be used at the right time and in the right way. Here are a few tips:

Apply on a bright day when no rain is expected for at least six hours. This gives the product time to dry and to be absorbed by the leaves of the weeds.

Apply sparingly. Contact weedkillers and the most popular systemic weedkiller on the market - glyphosate - are absorbed mainly if not entirely by the foliage. Apply too much and it simply rolls off onto the soil where it is wasted.

Do not apply during hot weather. Rapid evaporation causes the product to dry up before the weeds can absorb it leading to a reduced 'kill'.

Do not cut down the weeds prior to applying. Since most weedkillers are absorbed through the leaves, cutting them off can only reduce the amount of weedkiller that is absorbed.

Apply when the weeds are growing actively. To improve absorption, avoid applying when the weeds are growing slowly, such as during hot and dry, or cold weather.

Always read the label very carefully before use since different active ingredients have a different mode of action - some are safe to apply around

Deep-rooted docks require a systemic weedkiller to control them wanted plants, some such as sodium chlorate and path weedkillers, are not.

Keep a well-labelled sprayer or watering can (fitted with a dibble bar or fine rose) handy especially to apply weedkillers. It is all too easy to pick up the wrong can and apply to plants you wish to keep. Similarly beware of picking up a ready-to-use weedkiller spray, thinking you are applying an insecticide. Some look remarkably similar and it is an easy mistake to make.


Will weedkillers harm pets or wildlife?

Most modern weedkillers will not harm pets or wildlife once they have dried on to the leaves of the treated plants. Of course, it is important to keep both the concentrated and diluted product well away from pets and children. As with any other chemical, packs should be locked safely away and out of reach.

Will they harm the soil?

Most weedkillers are neutralised or broken down on contact with the soil. There are some exceptions - sodium chlorate and dichlobenil, for example, are residual weedkillers, designed to keep weeds at bay for several months. Products designed for paths, patios and

Patios Ideas


Doff Portland Ltd tel 0115 963 2842

Bayer Garden tel 0845 345 4100

Vitax tel 01530 510060

Scotts tel 0870 5301010

Gem Gardening tel 01254 356600

Growing Success Organics tel 01722 337744

drives often contain a residual element and should never be used on the veg garden.

Can I plant after using a weedkiller?

Always check the label before using a product to ensure that it is not going to render the area unusable for too long. As you will see from our chart on page 52, the most readily available active ingredients, glyphosate and glufosinate ammonium are biodegradable.

Will weedkillers affect my edible crops?

Not if you are careful to choose a weedkiller that is approved for use around growing plants, such as glyphosate and glufosinate ammonium. These will kill only the plants that they touch and are neutralised on contact with the soil. They cannot therefore be absorbed through the roots in normal use and will not persist in the soil to affect following crops.

Which weedkiller should I choose?

For use around fruit and veg, select one of the following:

  • Contact weedkillers (such as Weedol Gun!): Fast-acting, non-selective weedkillers, usually safe to apply around wanted plants provided they do not touch the leaves.
  • Systemic weedkillers (such as Roundup GC): These are absorbed through the leaves and travel throughout the plant in the sap. Excellent for killing deep-rooted / perennial weeds.

Sodium Chlorate Weedkiller

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