Plants Really Don't Like to Be Touched

Even a simple touch could cause major harm to your plant. Holly Lay/Flickr

There are a lot of New Agey gardening tips that abound. Some gurus recommend playing music for your houseplants, or having conversations with them, or even giving them gentle massages or an intimate touch now and then. Most of these practices are probably more for the benefit of the gardener than the garden, but generally innocuous enough.

That is, except for one. Your plants really dislike when you touch them, apparently.

A new study out of the La Trobe Institute for Agriculture and Food has found that most plants are extremely sensitive to touch, and even a light touch can significantly stunt their growth, reports

It's a finding that flies in the face of an age old green thumb myth, but La Trobe researcher Jim Whelan, who led the new study, says that his research is conclusive, and that we've got a lot still to learn about the growth of plants.

"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," he said. "Within 30 minutes of being touched, 10 per cent of the plant's genome is altered. This involves a huge expenditure of energy which is taken away from plant growth. If the touching is repeated, then plant growth is reduced by up to 30 per cent."

Why plants respond this way

Whelan and his team are still trying to figure out why plants respond, and on the genetic level, so strongly. They do have some theories, however.

"We know that when an insect lands on a plant, genes are activated preparing the plant to defend itself against being eaten," said Dr. Yan Wang, co-author on the study.

He continued: "Likewise, when plants grow so close together that they touch one another, the retarded growth defense response may optimize access to sunlight. So, for optimal growth, the density of planting can be matched with resource input."

Until more research is done, especially research that looks at the genetic mechanisms at play in these responses, it's all just speculation at this point. Still, the findings might already lead to new methodologies for how agriculturalists handle their crops, to best promote healthier growth.

It's worth noting that while the study found that plants often respond to just a single touch in these negative ways, it's really repeated touching that causes lasting stunted growth. That's because the plants are looking for patterns in the touching, to distinguish harmful touch from random touch.

So it doesn't have to weigh on your conscience each time you accidentally brush up against a bush during a jog through the woods.

The study certainly gives a whole new meaning to the idea of tree-hugging, though.