Some people are convinced that giving free hugs to your plants and stroking them like you would your beloved pet is what completes your green thumb. It is true that touching plants is calming for the human mind but do plants also enjoy these human cuddles?
Plants are generally best not touched to avoid stressing plants and activating their natural defense mechanisms. The sole exception is when plants must be touched for care tasks such as pruning, repotting, or treatment of infestations. In all other respects, plants prefer to be left untouched.
Scientific evidence suggests that touch is part and parcel of a plant’s interpretation of its environment. This means that touching plants causes them to react and the reactions are not always beneficial for your plants.
Read on to find out why touching your plants has more to do with defense mechanisms than green thumbs!
Can Plants Feel When You Touch Them?
Before we go into how or not to touch your plants at home, we need to know whether plants can feel touch at all. Because if they didn’t, we wouldn’t have to worry about it at all, as touching or not touching would be just the same from a plant’s perspective.
Feeling Without Nerves: Plants Perceive Touch Through Pressure Changes
As a matter of fact, plants can feel touch and react to it according to their interpretation of that touch.
You may know or have heard of certain plant types that visibly move when being touched such as Humble Plant (Mimosa pudica) closing its leaves or Venus Flytrap (Dionaea muscipula) snapping its tubular leaves shut. However, the majority of plants have invisible reactions to touch.
How can plants “feel” touch if they lack a nervous system? A recent study from Michael Knoblauch, Washington State University, tested plants’ reaction to touch microscopically and found out that plant cells react to pressure changes and pass the information on to neighboring cells like a wave flooding through plant tissue. The scientists were surprised by how finely tuned and sensitive this reaction is.
Humans and animals sense touch through sensory cells. The mechanism in plants appears to be via this increase or decrease of the internal cell pressure.
Michael Knoblauch, WSU (Accessed 2023-06-29)
The idea of Knoblauch’s team is that plant cells have strong cellular walls and even the slightest touch increases pressure inside the cells. That way plants can sense not only human touch but also softer touches such as the wind, heat, air pressure, humidity, insects, or other animals.
Tip: If you’re keen to learn more about how plants feel touch, check out this very informative video from the University of Western Australia on how plants are “in touch” with their environment:
What Touch Triggers In Plants: The “Fight or Flight” Response of Plants
One of our evolutionary acute stress responses is what psychologists generally term the “fight or flight response”.
In a stressful or dangerous situation, our nervous system prepares our body to either flee if the dangers seem too big to face or to stand our ground and fight. The bodily reaction to the situation leads to tension in our muscles, adrenaline outpours, and faster blood circulation.
These responses are evolutionary adaptations to increase chances of survival in threatening situations.
Psychology Tools (Accessed 2023-06-29)
Now, plants can neither punch insects to defend themselves nor run away from potential dangers. They have evolved as stationary beings. Does that mean they are defenseless victims of what happens around them? Not at all!
Their sense of touch is one of the crucial defense mechanisms plants have evolved over time and is just as elaborately fine-tuned and sensitive as our nerves are. Plants have their very own strategies to increase their survival in the face of threats.
How does their bodily defense work if not with nerves like ours? The answer lies in chemistry:
Nature’s Chemical Weapons: What Plants’ Defense Systems Look (And Smell) Like
The bodily reactions plants have come up with are mainly of chemical nature.
Plants release chemical substances (what we call smells) into the air to warn fellow plants of the danger or in the case of a bug or parasite attack to attract another insect that eats those little enemies that are munching on its leaves.
But that’s not all: When plants face imminent threats, they also start producing chemical substances like toxins in their leaves and stems to make them inedible or unsavory for herbivores or insects.
Professor Jim Whelan of the La Trobe Institute for Agriculture and Food at AgriBio calls this the “genetic defense mechanism” of plants as touch prompts the activation and alteration of certain genomes which are responsible for the production of these “chemical weapons”.
The lightest touch from a human, animal, insect, or even plants touching each other in the wind, triggers a huge gene response in the plant.
Jim Whelan, La Trobe (Accessed 2023-06-29)
As biologists Essam Darwish and Olivier Van Aken of Lund University state, this molecular defense mechanism has been known since Darwin but scientists only recently found out just how it works and research still needs to find out much more about how plants are able to intricately and precisely distinguish between different touches.
Does Touching Houseplants Stress Them?
Now that we know that plants certainly do feel and react to our touch, does it stress our houseplants out completely or do they not mind being touched all that much?
Well, if you’ve read through the first part of this post, you already know that touching plants causes them to react to it by activating some defense mechanism corresponding to the danger they feel exposed to by that touch. Hence, touch does create a stress response in plants.
Interesting Fact: While touch stresses out plants, touching plants however calms the human mind. As the authors Koga and Iwasaki mention in their 2013 study: “People experience an unconscious calming reaction to touching a plant”. They conclude that plants are indispensable to the human environment.
But is it that bad? Does it mean we have to tiptoe carefully around our houseplants making sure we do not ever even so much as brush the tip of a leaf? If you have houseplants, then you know that your plants did not die from touching them (and I am sure you did touch them, everyone does).
Touching plants doesn’t kill them but being too touchy with your plants can in the long run potentially stress your plants and reduce their overall growth.
As a General Rule: No plant enjoys being handled the way humans like to touch and cuddle. This is a simple but important fact to keep in mind about your green housemates. It is usually best to just let your plants be instead of fussing about them all the time.
Although some scientists like James Cahill from the University of Pennsylvania, showed that regularly stroking plants on a field harmed certain species tremendously, these results have to be treated with care.
In his study, they stroked certain plants from the bottom to the tip with bare hands over several weeks (not to mention all other external factors that come into play on a field). Such hands-on treatment is not something you would be doing on your houseplants – or are you? Well, if you did until now you should better let that habit become a thing of the past!
Why Some Plants Handle Touch Better Than Others
There are certainly some plant species that handle touch better than others. This depends on how they grow and live in their natural habitats.
In the tropics, for instance, light is rare on the ground level due to the dense foliage and growth above. Hence, many plants evolved not growing their own stem but as climbers that grow on other plants, trees, or objects to support them on their way up towards the light.
Those plants actually seek touch because wherever they touch something, they can latch onto that surface and keep growing up. Such plants naturally get less stressed by simple touches and include the following common houseplant species:
- Chinese Money Plant (Pilea peperomioides)
- Philodendrons
- Devil’s Ivy (Pothos)
- Waxplants (Hoya)
Other plants can’t handle touch at all. There are many succulent and cacti species living in arid, desert-like habitats where the heat of the sun burns down on them all day long. Many of these plants developed a powder-like sunscreen that covers their whole surface.
This powder is also called farina (= flour) or epicuticular wax and cannot be replaced once wiped off. If you touch these plants with your fingers, you will see a visible hole in the powdery protection layer. Other plants have developed an extra protection layer in the form of small hairs (trichomes) on the leaf surface as a protection against herbivory. Such protection can get damaged by touching the plants.
For those plants, refrain even from wiping dust away as it can harm their protection. It is best to only slightly blow on them to clean up.
This includes many of the following species:
- Echeveria (Wax Agaves)
- Sedeveria (Stonecrops)
- Pachyphytum (Sugaralmond Plants)
- Graptopetalum (Mother-of-Pearl-Plant)
Rule of Thumb: If a plant has a visible layer on its leaves, meaning they look covered in powder, glimmer, or with small hairs, do not touch the leaves at all.
When and How to Touch Your Houseplants: Practical Tips
As I already mentioned, touching your plants for care tasks is ok as the plant benefits from these tasks and they are not done as frequently as to stress your plant out. Still, there are some major things to keep in mind about when and how to touch or not to touch them:
How to touch plants:
- Wear gloves or clean hands with soap before handling plants
- Use a duster instead of wiping off dust with your hands
- Be gentle, never apply force
How not to touch plants:
- Do not touch plants with your bare hands to avoid distributing the oils of your skin on the leaves
- Do not press or squish on the leaves as it can destroy plant cells and protection layers
- Do never use force
When to touch plants:
- To eliminate pests and bugs
- To check for their health
- To prune them
- To repot them
- To gently wipe off dust (only plants where leaves have no powder/wax on their leaves)
When not to touch plants:
- Do not touch plants too often just for the pleasure of it
- Do not touch plants with a protective powder/wax on their leaves
- Do not touch seedlings or other parts of plants that are newly emerging such as new leaf tips as you might damage them
Reading Recommendation: Not only knowing how to handle your plants is essential, but knowing how to water your plants is just as if not more important. Read all about the proper way to water your houseplants in my post linked here.
Should My Houseplants Touch Each Other?
Generally, plants touching each other can provoke a similar stress response as human, insect, or other touches. It is recommended to leave enough space between plants in your home and to pot only one plant per pot.
“Social distancing” applies to plants as well: If one of your houseplants gets a pest it will spread more easily on others if they stand close to each other. Spreading them apart makes it easier to contain the spread of pests.
Now, you might think this goes against the grain of all current indoor gardening and design trends of making whole plant walls tightly packed with all sorts of greenery. But plant walls aren’t actually contradicting this as distributing plants on different hights and positions is a good way to keep them out of each other’s reach.
Please Note: When grouping plants or making plant walls, just make sure you don’t forget to trim them once they grow in each other’s way.
Plants touching each other lightly does not cause tremendous harm really. It can even have the benefit of securing equal growth among them because all have similar amounts of space and light available for growth.
So, even if the plants might grow a little less than when placed separately, all in all having less but a more equal growth among them might be a desired effect.
Tip: If you have a balcony and plant herbs in a container, make sure to check out which herbs do well next to each other and which don’t. For instance, basil can grow well next to parsley, but mint is best potted by itself as it takes away other herbs’ space to grow.
Short Wrap-Up: Refrain From Cuddling Your Plants and Only Touch Them Gently When Care Tasks Require It
Some plants don’t mind being touched, while others do. Generally, do not touch your plants unless it is necessary for their care.
Touch triggers a stress response within plants which will be bigger or smaller depending on how the plant interprets the danger it is facing from that touch.
Probably no houseplant will die from the effects of occasional stroking but if you can do without caressing them that’s better.
Related Questions
Do Plants Like Music?
While plants apparently do not like to be touched very much, there are plenty of scientific studies that show how music or sounds can stimulate plant growth. If a plant grows better with music, one would assume it likes it!
Keen to find out what type of music plants like and what to watch out for when playing it to them? Just click through right here to read my answer!
What Do Plants Need?
Plants might appear to simply need some earth, water, and light to be happy. Simple pleasures!
Though it is essentially true that plants do not need much to be healthy, what type of water, how much light, or what is in the soil they grow on matters a whole lot. Click right here to read more about what it is that plants need and why.