Are you fed up with slugs, snails, bugs, rabbits, birds, or weeds? Better than salt or pesticide, an electric fence works to protect them all day and all night. But how does electricity affect plants – do they get shocked and die?
Most electric fences nowadays will not burn or electrocute plants; the energy will simply leach into the soil. However, a plant exposed to extremely high voltage for prolonged periods (not common on fences) can cause a serious burn. The magnetic field generated by the electric current was shown to have even positive effects on plants.
Herb growers who use solar chargers and wood posts with two electric wires need not worry about shocking their plants. The benefits far outweigh the occasional power surge. Here’s what you need to know.
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When weeds touch an electric fence, all that happens is that the electric current (electrons) flows to the ground and the fence loses some of its power.
If the electrical charge is extremely high – and this is a hypothetical situation because electric fences have very low energy pulsing through them – a leaf may be burned and turn black, but the rest of the plant will keep on growing. This can happen in remote areas where a plant touches the wire of electric lines on top of wooden poles.
Plants are not affected only by the obvious current flowing on them (as in the case of a leaf touching a fence) but also by the magnetic field generated by electric currents.
In short, a magnetic field is an invisible force that affects all objects around it. All around you, there are magnetic fields (produced by your phone, cables on your walls). The magnetic field is generated by an electric current flowing on a cable. The higher the current, the stronger this invisible magnetic field is (and so the effect).
These are of course totally harmless to us and most of them also to plants. Despite there are many controversies on the real effect of magnetic fields on plants, it was found that strong magnetic fields do affect plant growth, more when they’re near each other and less when the distance increases. Don’t be confused: this rule doesn’t always apply.
Some studies indicate that magnetic fields produced by electricity flowing on conductors can affect plants positively (e.g., healthier and bigger plants). However, current directly flowing plants, especially if of higher voltage, can definitely burn them.. At the time being, no clear indication of the potential impact of electricity on plants has been found, especially when the magnetic field is considered.
FACTOID: Plants have no hearts like humans do, so an electric shock won’t give them cardiac arrest. However, the high electrical charge of a lightning bolt can burn parts of a large tree, yet the rest of the plant can still survive.
PRO TIP: To provide your plants with continuous protection without increasing your electric bill, try out a solar electric fence charger such as this one from Amazon.
Most electric fences work at low voltages so there isn’t enough energy to burn a plant. However, continuous contact with a high-voltage electric wire can burn a plant.
So how much electricity does it take to kill a plant? This depends on the type of fence.
There are two types of electric fence: the ones that produce spark discharges and the ones that produce continuous electricity.
Spark discharges: Electricity can be in the form of spark discharges. These are short, high-voltage pulses from 25 to 60 kV (1 to 3 μs). Spark discharges are effective for speeding up the ripening of fruits. Continuous shock waves can damage plant tissue enough to thin plants and to kill weeds
Continuous contact: An electrode that is connected to a high-voltage source (such as 15 kV, 54kW) can produce continuous electricity. When this touches a plant, the current will continue to flow as long as the plant is in contact. Fast heat can damage plant tissue, clear forest undergrowth, weeds from railway tracks, thin out rows of crops, and kill weeds as well as insects and pathogens.
PRO TIP: When you try out an electric fence such as this one from Amazon, ask if it produces a continuous electrical charge or pulses (or discharges electricity in sparks).
FACTOID: When you see a tree that’s been burned black by lightning, that’s essentially electrocution.
Electric fences that touch herbs divert the electricity into the soil so that the fence becomes less effective at plant protection. There are three (3) ways: keeping a margin of space, relocating, or regular trimming.
Space margin: In many photos of electric fences, you’ll see space kept between the fence and the field of plants. One reason is to keep leaves from contact with the electric wire. Another is to ensure that the power stays on the fence and not leach into the ground.
Relocate: If you’re growing herbs in pots, for instance, simply lift the pots and place them away from the electric fence.
Trim regularly: During rainy seasons, you might find that grass and vegetation grow faster than usual around an electric fence. If a weed hacker hits the power posts or gets tangled up with the power lines, try out a flexible hedge trimmer such as this one from Amazon.
FACTOID: Plants can generate electricity. One leaf can produce at least 150 volts, enough to light up 100 LED bulbs at the same time.
What Electric Fences Are Safest for Herbs?
Although insulated wires are safest for herbs to touch, electric fencing uses exposed wires to shock away plant feeders. The best strategy is to use an electric charger that emits low-voltage pulses. These won’t harm herbs and would only leach to soil or clay pots.
Most electric fences are temporary, consisting of three parts: an energizer, insulated posts, and one or more flexible wires that can be quickly assembled. Some sales literature is helpful while others are confusing as each claims a better product than others.
The most common types of electroplastic twine used as electric fencing materials are polywire, polyrope, and polytape.
Polywire fencing: This is an electroplastic ribbon with 3 up to 9 stainless steel filaments (depending on the product you choose). Check out polywire fencing material such as this one from Amazon.
Polytape fencing: Polytape wears out faster than polywire and is bulkier. In other words, a reel full of polytape can give you less fence than a reel of polywire. You can choose different widths of polytape, such as this one from Amazon.
Polyrope fencing: About nine (9) metal strands are braided into a 3/8 inch rope, so it’s a bit more difficult to rewind (and more expensive) than electroplastic twine with less metal strands. However, polyrope such as this one from Amazon is best for electric fences that use many wires.
PRO TIP: In steel or polyethylene wires voltage drops sharply when more than 1/2 mile from the energizer. However, at one mile away, there is no significant voltage drop in aluminum or fiberglass material.
Electroplastic net: A single net (also known as “electroplastic netting” or “electric mesh netting” is about 160 feet long and can enclose about 1,600 square feet (40′ x 40′).
An energy controller such as this one from Amazon pushes electric pulses into the fence wire every second. When an animal touches the wire, excess energy travels through the animal and goes into the ground.
Invisible Fence: An invisible fence is basically a collar around your pet. When they reach the parameters you program into the collar, they receive a mild electric shock. Thus, they learn not to go beyond certain areas. This keeps your plants safe from household pets. Check out an invisible fence such as this one from Amazon.
FACTOID: Although aluminum does not rust and conducts electricity better than steel, thin aluminum filaments corrode and become brittle.
Can an electric fence kill a plant or a pet? No. An electric fence with low current or low-voltage pulses can’t kill or permanently hurt any pet or plant.
What happens when a plant touches an electric fence? If only a plant touches a low-voltage electric fence, the electricity will flow down into the ground.
Why doesn’t an electric fence kill a plant? A properly designed electric fence cannot electrocute a plant because it has low amperage and emits pulses of electricity instead of a constant current. Altogether, the fence is uncharged longer than it is charged. You can adjust your electric fence to different voltages and power levels.
How can an electric fence kill plants? If the voltage is high enough and the leaves or branches are wet, the electrical current can kill the part of the plant that constantly touches the wire. Whether the fence produces a steady current or pulsed energy, the part of the plant touching the wire will begin to burn away and turn black, and will eventually die.
How much electricity can kill plants? Extremely high electrical power is toxic to plants, even big trees. It can take days or even weeks to permanently kill plants, trees, or grass through the roots using electricity only. The plant cells containing water will dry up, wither, and die, but the rest of the plant will continue to live.
Electric fences are convenient and effective ways of protecting your plants from damage by pets, wildlife, slugs, snails, and the like.
Most electric fences have low amperage and emit low-voltage pulses and cannot harm plants that are in contact. The electricity will simply flow through the plant and into the soil.
However, with extremely high-voltage electrical current or in constant contact with a wire that carries a steady current (not pulsed current), parts of a plant – or even the entire plant – can be damaged.
For plant safety, use electrical fencing that has low-voltage electrical current in pulses rather than a steady current. Make sure all fences (not just electric ones) are properly grounded. Use organic pots such as this one from Amazon rather than metal ones.
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“The Art of Electric Garden Fences” by By G. Damerow in Mother Earth News
“Using electric current as a weed control method” by H. Sahin & M. Yalınkılıc in European Journal of Engineering and Technology Research
“Effects of electricity on plant responses” by D. Dannehl in Scientia Horticulturae
“Effect Of Electricity On Growth And Development Of Several Plant Species” by V. Novak & M. Bjeliš in HBD-SBC
“The Effect of Electricity on Plant Growth” by B. Artem & T. T. Albertovna
“Solar based electric fence for smart farming” by K. D. Sharma, et al in International Journal of Electrical Power System and Technology
“Electrical stimulation boosts seed germination, seedling growth, and thermotolerance improvement in maize (Zea mays L.)” by Z. G. Li, et al in Plant Signaling & Behavior
“Electrical methods of killing plants” by M. F. Diprose & F. A. Benson in Journal of Agricultural Engineering Research
“Fences that Work: Temporary Electric Fence Materials Evaluation” by the University of Maine