This article is intended to give a basic overview of Weed Killers used in the garden, including the hard surfaces. Using the wrong product on lawns for example, can have disastrous consequences. We've witnessed this many times and have often been asked for advice on using them, but it’s a lot to absorb and remember. So here you can return to jog your memory, if the need ever arises.
If you understand some basic principles on the selection of weed killers, you'll have much more confidence in working with them. This then gives you a better chance of achieving good results safely. Understanding the main terms as set out below are the essentials and hopefully will give you a clearer picture on their use.
Total Weed Killers - Total Herbicide
A TOTAL weed killer is non-selective, this means that it will kill any green-leaved plant that it comes into contact with. It will NOT differentiate between broad leaved weeds such as Dock, Daises, Dandelions and innumerable other broad-leaved garden weeds and the different species of grass that make up your lawn. The Broad leaved weeds are referred to in botanical parlance as Dicotyledons and the grasses are referred to as Monocotyledons. Total weed killers are designed to kill BOTH. What's the difference between Dicotyledons and Monocotyledons?Well, the former has two embryonic leaves after the seed first germinates and the latter only has one, but we wander off into the realms of botany here, so if you would like to learn more just follow the links above.
You would NEVER USE A TOTAL WEED KILLER ON A LAWN unless you wanted to kill the entire lawn. You would use a total weed killer to completely kill all broad-leaved weeds, Dicotyledons AND grasses, Monocotyledons.
Selective Weed Killers - Selective Herbicide
A SELECTIVE weed killer will work as its name implies; it will target (select & kill) only the weeds that it was designed to eradicate. In the garden a selective is mainly used to control the wide range of broad leaved weeds, Dicotyledons, and leave the grasses, Monocotyledons, unharmed.
Both selective and total weed killers contain a wide range of ACTIVE INGREDIENTS, these are the chemical compounds that kill their intended targets, and they work in various ways. If you examine the label on the container that holds your weed killer, you will see these active ingredients named.
Deciding which selective you should use mainly depends upon the range of broad leaved weeds that are causing you the problem. This is because different formulations of selective weed killer are designed to target different groups of broad leaved weeds. If this is starting to sound confusing, you’re forgiven, because it can be at first.
It does help greatly if you can identify the range (species) of weeds that you want to kill. Then all you need to do is read the label on the container and see if that particular selective weed killer is suitable for your needs. If you can’t identify the range of weeds that you want to kill, you may choose a product that will do a pretty good job but leave one or two species still hanging on for survival, and you will achieve a partial kill. The reason for this is SUSCEPTIBILITY. Some weeds are more susceptible to a particular formulation of active ingredients than others. So, if possible, first identify the range of weeds to be killed, then choose your product carefully.
Residual Weed Killers - Residual Herbicide
RESIDUAL weed killers sometimes referred to as “long lasting weed killers” persist and “reside” in the soil after application. This gives control over a longer period. They are often used on hard surfaces, patios and drives for instance, but not always. One of the ways they work is by killing the weed seeds as they germinate so they don’t get the chance to establish themselves. This residual activity can last up to six months. NEVER USE A RESIDUAL WEED KILLER ON A LAWN unless you have a very good reason, and you know what you're doing.
This is only a basic introduction into what can be a bemusing subject, but the takeaway here is, if this little article has given you food for thought before you buy any weed killers for your garden, and you chose them carefully, then its served its purpose. Quite often it seems, people make the wrong choice and have to suffer the consequences. If you are in any doubt whatsoever about choosing the correct product, please take your time and make your choice cautiously.
One last reminder ONLY USE A SELECTIVE WEED KILLER ON YOUR LAWN! and ALWAYS READ THE LABEL regarding application instructions, or you'll most likely spoil your day!
If you'd like much more detailed information about weed killers, there's a brilliant free Royal Horticultural Society PDF download https://bit.ly/weedkiller-pdf It makes wonderful bedtime reading.