Your resource for information on weeds, identifying weeds, weed control, weed killer, herbicides, organic and natural weed killer treatments, weed history and where to buy chemical weed killer. Also check out our hints and tips section for lawn and grass weed control advice.
Check out the links below to navigate the site and find what you are looking for:
Where to Buy Weed KillerDobbiesIdentifying Weeds Weed Killer InformationOrganic WeedkillersWeed Guns
Application Weed TypesHealth & Safety Edible Weeds Weed Quotes Invasive Weeds Noxious Weeds
Notifiable Weeds Injurious Weeds Pernicious Weeds ApplicationPopular Weed Killer IngredientsWeed Killer Links
There are many different types of weed killer; there are organic weed killers, systemic weed killers, non-selective weed killer, selective weed killer, pre-emergent herbicides, post-emergent herbicides and residual herbicide. As you can see there is quite a lot of choice. So which one do you need? If you require a grass killer see non selective herbicides. Below is a table which places the weed killers in their prospective categories:
Categories |
What do they do |
Weed Killers |
---|---|---|
Organic Weed Killers Natural Weed Killer | Organic or Natural Weed Killers are good alternatives to chemical weedkiller and are more eco-friendly. On the whole these ingredients are non-selective. Unless using your hands or hoe!! |
Distilled White Vinegar |
Non-Selective Systemic Weed Killers | Like it sounds a non-selective weed killer is not selective. So it will kill any plant it is applied to. Unlike contact weed killer, systemics will kill the root of the plant. Although it may take longer to see any results. Suited in control of annual and perenial. Less effective during times of cold and drought |
Ammonium sulphamate (AMS) Glyphosate Amitrole Fluroxypyr Imazapyr Picloram Triclopyr |
Non-Selective Contact Weed Killer | Like it sounds a non-selective weed killer is not selective. So it will kill any plant it is applied to. It does not kill the root system but provides rapid top growth killing. Suited to control of annual weeds but less so to perenials |
Quick Pro Dry Scythe Brush Killer BK-32 Ammonium Octanoate Ammonium Decanoate Ammonium sulphamate (AMS) Paraquat Diquat Gluphosinate-ammonium (Glufosinate) Pelargonic acid - (nonoaic acid) Weedol MAX Sodium Chlorate Atrazine - Banned in EU dicamba Linuron |
Selective Weed Killer | As the name suggests, this is a more targeted type of weed killer. Normally targeting broadleaved plants and leaving grasses unharmed. Commonly used for weed control on lawns. Selective weedkillers action is also systemic. |
2,4-D aminopyralid clopyralid Imazapic Dichlorprop Dicamba Dichlorophen Mecoprop-P (MCPP) MCPA Metosulam Bastion T Super Selective Greenor |
Pre-Emergent Herbicide | See non-selective residual Weed Killer |
See non-selective residual Weed Killer |
Post Emergent Herbicide | See non-selective contact weed killers |
See non-selective contact weed killers |
Non-Selective Residual Weed Killer | Also known as pre-emergence herbicides, they are non-selective and remain in the soil, killing germinating seeds and shoots from perennial roots. |
Atrazine - Banned in EU Metolachlor Pendimethalin Dichlobenil (2,6-dichlorobenzonitrile) Diflufenican Diuron Flufenacet Metosulam Oxadiazon Simazine Sodium Chlorate Tordon |
Popular Weed Killer Ingredients:
Below is a table of popular weed killers and their active ingredients:
Trade Name |
Type |
Active Ingredients |
Use |
---|---|---|---|
B&Q Complete |
Systemic |
Glyphosate |
General and spot weed killer |
Casaron G4 |
Residual |
granules |
On areas where no growth is wanted. |
Gramoxone |
Contact |
Paraquat |
fast acting ground clearance (agricultural use only), perennial weeds not completely killed |
Pathclear |
Systemic and Residual |
Diflufenican and Oxadiazon |
paths and gravel |
Roundup |
Systemic |
Glyphosate |
general to clear for planting and as a spot weeder |
Tumbleweed |
Systemic |
Glyphosate |
general to clear for planting and as a spot weeder |
Weedol |
Contact |
Diquat |
fast acting ground clearance, perennial weeds not completely killed |
Weedol MAX |
Contact |
Pelargonic acid |
fast acting, perennial weeds not completely killed |
Obviously all the major DIY stores, Garden Centres and even Super Markets will stock weed killers like Roundup, Path Clear and Weedol. Roundup weed killer is probably the most well known and used of the spot weed killers.
For some of the more specialised and industrial ones try some of these websites:
Timing the application of weedkillers or herbicides is very important. The best time to apply weedkiller for almost all types of weeds is when they are seeding. Since most weeds spread by seed it makes sense to apply before flowering.
Biennial weeds tend to be more easily eradicated in their first season when they are seedlings or small rosettes.
When attempting to treat perennials an application of a systemic weedkiller in the autumn when they are transferring sugars to the roots and other underground parts for winter storage can be very effective. Especially for weeds that are difficult to control. For the best results allow the weed to develop plenty of leaves to increase the surface area which can absorb the herbicide, which in turn will be passed down to the roots. Make sure and leave them intact until the weed shows signs of dying.
Weedkiller will have less effect on plants/weeds under stress such as waterlogging, drought or low temperature as they are not as healthy and growing poorly. Plants have a vascular system which takes water up through vessels (xylem) and moves the sugars that are produced in the leaves to the rest of the plant through other vessels (phloem), so it is best to apply weed killers during periods of good growth when the sap is moving around the plant at a higher rate and the chemical will be taken with it.
If the weed is well established with a good perenniating system or if there is insufficient topgrowth to absorb enough chemical, one application may not be enough to remove it completely. If the weed has been present for some time there will be a store of seeds allowing it to re-establish itself e.g. Clover, Daisy and Creeping Buttercup in a lawn.
The method of application must also be taken into consideration: How large is the area and what percentage of the area is covered by weeds? Do we have to be selective by using spot weed control methods and killers such as Roundup.
Most domestic use weed killers are available in ready made sprays which are useful for spot treatment of weeds such as roundup weed killer. Use these sprays when you want to target a few weeds on paths or grass etc.
A watering can with a sprinkle bar fitted is the easiest way to apply weedkiller evenly over a larger area such as a garden patio, driveway or path. One of the main drawbacks is nozzle blockages. This can be reduced by flushing them out with clean water before and after use. Sometimes the mixture froths up while diluting due to the inclusion of surfactants which help mixing and improve the wetting of the weeds. To reduce the foaming effect try running the water down the inside of the can or filling down the spout. Using an open ended hose to fill from below the surface will have a similar effect.
Always make sure powdered concentrate is completely dissolved or suspended, as small lumps will clog the nozzle. Liquify the powder in a small quantity of water first, crushing and melting any lumps, then top up to the required volume.
It is of course imperative to apply weedkiller at the correct rate; too little may be ineffective and could lead to the development of resistance; too much is a waste of money and the weedkiller may damage non-target plants. You can calibrate and test the sprayer or sprinkler using plain water.
When carrying out weed control of larger areas more specialised equipment will need to be utilised. Using a knapsack is the next step up and is useful for spraying edges in fields, road verges, allotments and difficult to reach areas. Knapsacks also offer a lot of control and accuracy. If the required area to be treated is large (football pitch, golf course etc) then a tractor sprayer would have to be used and it would be advised to use a professional weed control company. See Growing Concern Scotland Ltd.
Always try and apply weed killer when it is dry and not windy. This ensures accuracy and that the weed killer is correctly diluted. Another benefit is when applying weed killer to concrete, flags or gravel, it is easier to see what areas have already been treated so no area is dont twice or missed altogether
It is likely the chemical's directions give a quantity per square metre (m²). Try marking out an area in m² and apply water at your pace, note the quantity needed to fill the watering can up again and divide by the number of m² marked out. Repeat this a few times and take an average. This is the volume of liquid applied per m², so add the amount of concentrate needed per m², multiplying up for a larger container.
For example:
An area 6m x 10m = 30m²
Will require 2 watering can fulls which contain 4.2 litres
4.2 divided by 30 = 0.14 or 140 mls per m²
So if we assume that the application rate is 6g per m²,
we should add 6g to every 140mls equalling around 43g per litre.
This also shows that a watering can of 2.1 litres covers approximately 15 m² (2.1 divided by 0.14).
Please note that these measurements and figures are from experienced sources and can vary with application volume controlled by vehicle/walking speed.
There are many different weed 'types' that are commonly discussed these include: Invasive Weeds, Noxious Weeds, Notifiable Weeds, Injurious Weeds, Pernicious Weeds. These are discussed below:
Weeds commonly connected with the phrase 'invasive' are Japanese Knotweed and Giant Hogweed.
Weeds Act 1959:
The following 5 weed species are covered by this Act:
Of these, ragwort is the most pernicious. It is poisonous to grazing animals such as sheep, cattle and horses and can prove to be fatal to them. The sap from Giant Hogweed is extremely irratative to skin.
Wildlife & Countryside Act 1981:
The main weed covered by this act is:
Japanese Knotweed [fallopia japonica]. It is illegal to move from one place to another and should not be dug up. It is classified as hazardous waste.
Noxious weeds can reduce crop yields, displace desirable plant species, destroy beneficial native habitat, damage recreational opportunities, clog waterways and lessen land values.
A landowner with Japanese Knotweed on their land is legally obliged to address the problem. You could try eating it as it tastes like rhubarb!!
Land owners have a legal obligation to do something about notifiable weeds on their land.
Japanese knotweed, giant hogweed and Himalayan balsam are not considered to be ‘injurious’. Injurious refers to a number of species listed under the Weeds Act 1959. These are:
Defra has produced leaflets that will help you to identify these species.
If there is any injurious species on your land, you are responsible for controlling them. The weeds must also be stopped from spreading into adjoining land. An enforcement notice can be served to make sure of land owner compliance.
Aegopodium podagraria (Ground-elder or Bishop's Weed)
Cirsium arvense (Canadian Thistle)
Convulvulus arvensis (Bindweed)
Phalaris arundinacea (Canary Reed)
Polygonum cuspidatum (Japanese Knotweed)
Sinapsis arvensis (Wild Mustard)
Solanum dulcamara (Deadly Nightshade)
Tanacetum vulgare (Tansy Ragwort)
Weed wands are smaller than the guns and are more suitable for people less confident working with flammable material and heavier equipment. The wands are perfect for smaller areas like driveways etc, they are also easier to lightr and use. Buy them here:
Weed guns can be very effective over fairly large areas like allotments. They burn at up to 2000 degrees Farenheit, enough to frazzle the hardiest weed. Most run on parafin and sound like a small jet engine when ignited.
When using a weed gun on areas rife with weeds, two burns might be required, normally 5-7 days apart. Once burned, the weeds should wilt and die. Burning does not kill the weeds root system but continual burning will deplete the reserves and eventually kill the roots.
Two of the best weed guns can be found here:
Mower Magic Sheen Flame Weeders
Or if you dont want to buy you can hire one here:
Weed flame guns are not exactly and organic weed control method but are probably less damaging than chemical options, plus the carbon from the burnt weeds must put some nutrients into the soil.
Great care and attention must be taken when storing, handling and applying any herbicide. Some can be absorbed through the skin and contact can lead to rashes, nausea and even death in the case of paraquat; especially through cuts and abrasions.
Dont be fooled by the flashy, innocent looking containers of herbicides on the shop shelves. They may look harmless and easy to use. However, there is gathering evidence that the active ingredients are doing damage to the environment, wildlife and us.
MCPA and 2,4-D are used widely to control weeds in grass, recently more evidence has prompted calls for them to be banned. Research by the US Environmental Protection Agency has concluded that there is an increased risk of heart and breathing problems in new-born infants.
2,4-D and MCPA are chemically similar to 2,4,5-T which is only a few chemical steps away from tetrachlorodioxin, and the latter can be an impurity in production if it is not carried out properly. A combination of 2,4,5-T and 2,4-D make up Agent Orange which gained notariety during the Vietnam war in the 1960s. The 2,4,5-T itself is not toxic, but concentrations of 20 - 30 parts per million of the dioxin impurity can cause birth defects and cancers.
Dont take any chances with chemicals its just not worth the risk!!
Mow your lawn or grass as close to the ground as possible, especially during the late spring and early summer, when crab grass makes its annual attempt to take over the world. By cutting the grass as close to the the ground as possible, you can prevent crab grass from sprouting.
Keep pH level neutral or slightly acid, at 6.5 to 7.0. Dandelions prefer more acid soil while lawn grasses thrive in neutral soil.
Grow dense, deep-rooted grass because deep root systems allow them to keep a dense canopy even during the hot, dry months when crab grass is rampant.
Be careful when applying weed killer to lawns and grass as if a non-selective chemical is used it will act as a grass killer too! If hpowevere a grass killer is what your are looking for then a non-selective herbicide is for you.
Mulch is traditionally applied at the start of the growing season (although difficult to get Autumn leaves at this time).