Whether you live in the countryside with treated fields nearby, in the city or even along the road, a protective hedge against pesticides or other pollution will be helpful…
The idea for this article came to me after a question Laurent asked me:
I’m about to make my dream come true or… to make a big mistake.
I found a beautiful plot of 2,300 m² near a village where I could create the garden of my dreams. The only problem is that it is attached to fields at the western limit (latitude). there are 2-3 large poplars, a path between the land and the fields, but hey, I’m going to get all the pesticides and other chemical delights from my neighbor farmer. And since I’ve just read an article in Le Monde stating that it takes at least 100 meters between the field and the boundary of a field to reduce the concentration of these sweet, super healthy products, I’m very wary. Hence my question, since I have space, would you recommend magical shrubby hedges to absorb all the chemicals (bad hedge…) and thus protect the rest of the garden? or else it’s useless because it’s still passing or somewhere else…
Thank you very much for your advice and have a nice day.
Let’s be clear: there is no “magic” hurdle.
A dense hedge will reduce pollution…but not eliminate…
Water, soil, wind are possible vectors.
And all this is not “fixed” (for example, the wind is oriented differently from one day to the next).
But even though it will never be able to catch everything, a suitable hedge will significantly reduce the pollution that ends up in your garden.
Let’s start by looking at some principles to best protect your land from environmental pollution (chemical treatments, road pollution, factory discharges or various types of noise pollution).
A few principles for a protective hedge
Choose varieties adapted to your region
Before making any other consideration, in my opinion it is important to give preference to species adapted to your region.
Indeed, these are the varieties that will grow best in your home.
The acidic or calcareous nature will also be a determining factor in choosing the species to integrate into your hedge.
Different layers of plants
The different heights of the vegetation are called “strata”.
So we have low plants (usually “herb-like”), shrubs and trees (which grow more or less high depending on the species).
Diversifying the species to be integrated in a hedge, by drawing on the different layers, will not only allow to form a barrier at different heights, but it will also play a fundamental role in terms of animal biodiversity (each layer serves as a refuge, or pantry, to different animal species).
A good thickness of the hedge
The thicker the hedge, the better the protection.
For example, you can make a row of trees (for height) along the path, then shrubs and herbaceous plants a bit back (for more width but also to compact the vegetation at the bottom of the hedge).
But also don’t forget to bring plants with evergreen foliage (for example laurel or a few cypress or other conifers), otherwise your anti-pollution barrier will be very bare in winter…
Integrate “absorbent” plants
Some plants are known to be more “pollution absorbent” than others, such as the cotoneaster franchetii, cited by recent studies (see here).
The cherry laurel is also one of the recommended varieties to reduce pollution (see here). But beware… the tempting fruits are poisonous!
In addition to a living hedge, heather strips would be relatively effective at limiting herbicide spraying, at least at the strip level.
Well… All in all, this ability to absorb pollutants is quite relative (the cotoneaster franchetii, for example, only represents a 20% gain compared to other plants).
And for the reasons mentioned above, there is no question here of planting a hedge that would consist of only one of these species.
On the contrary, I advise you to diversify as much as possible by planting different species (deciduous and evergreen), plants of different heights and species “resistant” to pollution … all spread over as wide a width as possible.
Which species to include in a protective hedge?
As we have seen, the choice of species to include in a hedge depends on your region (pay attention to the species present there and do not hesitate to ask your grower for advice), but also on the texture and PH of your soil (I present, in Mon Potager au Naturel, simple tests to determine the main characteristics).
Here is a document that, even if written more specifically for Cantal farmers, will give you a large number of very useful indications (distances to be respected with the neighborhood; species adapted to acidic or calcareous soils or even to the texture and soil depth ; objectives; ecological interests, etc.) to make your choices and plant your hedge:
Your questions and comments are welcome below…