There are many gardening tips. Some suggest playing music for your houseplants, having conversations with them, or even giving them a gentle touch now and then. Most of these practices are probably more for the benefit of the gardener than the garden, and generally harmless enough but except the last one. Your plants really dislike it when you touch them.

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(遏制) their growth. "The lightest touch from a human, animals, insects, or even plants touching each other in the wind, can cause a huge gene response in the plant," said Jim Whelan, who led the new study. "Within 30 minutes of being touched, 10% of the plant's genome(基因组) can be changed. This involves a huge expenditure(消耗) of energy which is taken away from plant growth. If the touching is repeated, then plant growth is reduced by up to 30%. "

Whelan and his team are still trying to find out why plants respond, at the genetic level, so strongly. They do have some theories, however. "We know that when an insect lands on a plant, genes are activated(激活) preparing the plant for defending itself against being eaten," said Dr. Yan Wang, coauthor of the study.

Until more research is done, it's just a guess at this point. Still, the findings might already lead to new methods for how agriculturalists deal with their crops, to best promote healthier growth.

It's worth noticing that while the study found that plants often respond to just a single touch in negative ways, it's really repeated touch that causes lasting stunted growth. That's because the plants are looking for patterns in the touching, to tell harmful touch from random touch. So it doesn't matter if you accidentally brush up against a bush during a walk through the woods.

More than half the planet's population now live in cities, with limited access to the natural world. For Europe and Latin America, the figure is more than 70%. ①

Gardening in particular is an opportunity for everyone to have such kind of experience, even if they live in built-up areas. It is typically seen as moderate(适度的) intensity exercise equal to playing doubles tennis or walking at a speed of 3. 5 mph, so it has similar fitness benefits.

Home and gardens have long been important for family food production, but gardening can also encourage people to eat more healthily and act as an educational resource of nutritious food. In fact, children who take part in gardening and grow their own food have a greater preference for, and increased consumption of, fruit and vegetables.

Research has shown that gardeners generally have greater life satisfaction, raised self-esteem and fewer feelings of depression and anger than non-gardeners.

This last point suggests that the mental benefits of gardening may be more than just a side effect of the physical exercise involved. People with strong social networks have increased life expectancy, less stress and fewer visits to the doctor. In addition, spending time outdoors in a natural environment helps us to feel less stressed, reduce the symptoms of depression, and improve our concentration and attention.

All the evidence shows there's a strong relationship between gardening and health, but we only know for sure that there is connection, not "cause and effect". We also need to directly examine the immediate effects of gardening on people who have never previously taken part or are suffering from mental and physical ill health.