This is the question every gardener asks when faced with an overrun lawn: how can a selective herbicide can it destroy weeds while leaving the grass intact? At first glance, it seems almost magical. In reality, it all rests on a precise biological principle that distinguishes weeds of grasses of the lawn.
This article explains in detail how a selective herbicide works, why it does not affect the grass, what are the advantages for the lawn, and what precautions to take to use it effectively.
Selective herbicide or total herbicide: the fundamental difference
Before understanding selectivity, it is necessary to distinguish two product families. A total herbicide, like a glyphosate product, is non-selective : it destroys almost all plants it touches, weeds such as grass. Applying it on a lawn would be to burn it entirely.
A selective herbicide, on the other hand, acts in a targeted way. It is a herbicide at selective action that eliminates weeds broad-leaved while preserving grasses that make up the grass. This is exactly what a gardener who wants weed its lawn without having to redo everything. The range of selective herbicide is entirely based on this principle.
Why a selective herbicide only destroys weeds
The key to selectivity lies in a biological difference between plants. The grasses of the grass, such as ryegrass or fescue, are monocotyledons: their leaves are thin, upright, and vertical, and their growth point is protected at the base.
The weeds undesirable in a lawn, such as clover, dandelion, plantain, or daisy, are on the contrary dicotyledons: their leaves are broad and spread out, and their growth occurs at the top.
A selective herbicide exploits this difference in three ways:
- Leaf surface. The broad leaves of weeds retain much more product than the fine leaves vertical leaves of grasses, on which the liquid slides.
- The growth mode. The protected growth point of grasses escapes the product, whereas that of weeds, exposed, is directly affected.
- Biological sensitivity. The active substances of a selective herbicide disrupt the growth of dicotyledons, while the grasses are naturally much more tolerant.
Result: the weeds absorb the product through their leaves, transmit it to the roots and wither, while the grass continues to grow normally. This is the whole point of selectivity.
How the selective herbicide works inside the plant
Most selective herbicides are systemic. Once sprayed on the foliage, the product is absorbed and then circulates in the sap of the weed down to the roots. It is this internal circulation that allows destroy the entire plant, and not just the visible part, which greatly limits regrowth.
On weeds broadleaf, the effect mimics anarchic growth: the plant exhausts itself and dies. The grass, it is not affected by this mechanism. This is what distinguishes a selective herbicide than a simple contact herbicide, which would only burn the surface without reaching the roots.
The advantages of a selective herbicide for the lawn
Choose a selective herbicide rather than a total product has several advantages concrete benefits for lawn maintenance lawn.
- You keep a uniform lawn, without burnt areas or bare to replant.
- You eliminate weeds deeply, roots included, which spaces out treatments.
- You clean the lawn without get rid of painfully every plant by hand.
- You reduce manual weeding, tedious on well-established dandelions and clover.
- You get a clean result without completely redoing the lawn.
For paths, flowerbeds, and grassy areas, it’s the right compromise between efficiency and respect for garden. A weeding well managed naturally fits into a routine of gardening maintenance, and weed at the right time prevents unwanted plants from returning. Space out weedings over time becomes possible, since the selective herbicide acts down to the roots.
How to properly apply a selective herbicide
The selectivity only works fully if the product is well applied. Some rules for proper use effective without risk to the grass.
Treat actively growing weeds, in spring or early autumn depending on the product, when the plants grow and absorb the substance well through their foliage. Dilute the product at dosage indicated and apply evenly, at sprayer or at thewatering can, without overdosing. For weeds isolated, a weed knife fully complements the treatment. Avoid windy days or imminent rain, and do not mow just before nor just after, because the weed needs its foliage to absorb the product. Let it work several days before the next mowing, allowing the selective herbicide takes effect while preserving the grass.
A good complementary reflex: after treatment, support the grass with a fertilizers suitable for thickening grasses and limit the return of unwanted plants.
Precautions and mistakes to avoid
Even targeted, a selective herbicide remains a phytopharmaceutical product that requires rigor.
- Respect the doses : overdosing can stress the grass, despite the selectivity.
- Do not use the product anywhere other than on the lawn, nor on the vegetable garden nor on flowerbeds, as it targets plants broadleaf, including those you want to keep.
- Keep children and animals away until completely dry.
- Wear gloves during preparation and application.
- Avoid treating during severe drought, a grass already stressed does not tolerate the product well.
Also keep in mind the legal framework: in France, the sale and use of herbicides synthetic are strictly regulated and reserved for authorized users.
What selective herbicides are available on the market?
There are different selective herbicides for grass, in concentrated liquid form at spray or granules to spread. These herbicides cover various needs: targeted treatment of weeds resistant, regular maintenance of the lawn, fast action or gentler approach. All these weedings selective share the same principle, but each herbicide targets a specific use, and these products selective are aimed at both gardener amateur or professional.
The right choice depends on your area, the type of weeds at eliminate and the season. However, avoid using these products on plants of the vegetable garden : they are not made for that. Choose rather the reference suited to your grass in the range of selective herbicide to find the product that suits your garden.
Frequently Asked Questions
How does a selective herbicide distinguish weeds from grass?
It exploits the biological differences between grasses grass, with fine, vertical leaves, and the weeds broadleaf. The latter retain more product and are more sensitive to it.
Why isn’t the lawn destroyed by the selective herbicide?
The grasses have a protected growth point and a natural tolerance to active substances, whereas weeds broadleaf absorb the product and wither.
What are the advantages compared to a total herbicide?
A selective herbicide preserves the lawn, avoids burnt areas and eliminates weeds deeply, where a total herbicide would destroy everything grass.
What precautions should be taken when using it?
Respect the doses, treat in calm weather, apply only on the grass, keep animals and children away until dry and wear gloves.
If a selective herbicide does not destroys only the weeds without damaging the grass, it’s not magic, but a matter of biology: it targets plants broadleaf, the dicotyledons, while sparing the grasses of the lawn. Properly applied, it offers a lawn dense and clean, without the damage of a total herbicide.
To choose a product suitable for your area and your weeds, discover the range of selective herbicide and select the solution best suited to your garden.
