A variant of the game Twenty Questions begins with simple Linnean categories: “animal, vegetable, or mineral?” In the minds of most, only one of these categories — animals — contains thinking and feeling organisms. Recent science, however, has complicated this picture.
What if plants are actually closer to animals than minerals in terms of their ability to perceive and interact with the world? Does that then make gardening a social activity rather than a solitary one?
The emerging and sometimes contentious field of plant neurobiology has been accumulating evidence that plants are perceptive and proactive in their environments, rather than simply being reactive automata. Founded by the Italian plant physiologist Stefano Mancuso and chronicled in his book Brilliant Green, the study of plant neurobiology rests on the belief that — even with their notable lack of neurons — plants are fundamentally intelligent life forms that can communicate with each other, navigate their environments, and solve problems. Mancuso’s ideas have been promoted in the mainstream by the popular but often controversial journalist and commentator Michael Pollan, creating debate among scientists, horticulturalists, and even vegetarians.
Though the field plant neurobiology was officially born with Mancuso and his International Laboratory of Plant Neurobiology (est. 2005), the ideas themselves are much older. The polymathic Bengali botanist, archaeologist, and physicist Sir Jagadish Chandra Bose (1858-1937) — a pioneer of radio science and Science fiction alike — made the biophysical discovery that plants conduct information about their environments electrically, rather than just chemically (as previously thought). He published his findings in a book entitled The Nervous Mechanism of Plants (1926).
In the 1970s, a book called The Secret Life of Plants attempted to expand upon the work of scientists like Bose, tying it together with rather odd contemporary experiments involving attaching polygraphs to plants. The book concluded that plants were supernatural, and had attributes like memory: these claims, however, have been roundly debunked as non-reproducible pseudoscience.
So while not all the science on the matter has been reputable, some recent discoveries validate more the conservative claims of plant neurobiology: for example, trees have been found to ‘talk’ to each other using an underground network of fungal mycelium.
Outside of the realm of conventional science, there are many indigenous traditions that consider plants as perceptive beings. The Kuttia Kondh of Odisha, India, for example:
[...] perceive trees and other plants as creatures akin to animals and human beings. The life of a plant, its pattern of growth, germination, and association with other plants inspire the Kuttia Kondh to believe that all plants socialise with one another and communicate and interact with other plant species. 
This view is one that is sometimes shared by gardeners, who often come to name individual plants, or perceive that the plants in a home or garden react to each other and their environments over time.
Even for those who don’t buy into the hype about plant sociality, there are ways in which social relationships with plants can be symbiotically beneficial. The long-held folk belief that talking to plants makes them grow faster is bolstered by the fact that plants use the CO2 that animals like humans exhale into the environment. So while a plant that is talked to is perhaps not growing from sheer encouragement, it is taking a byproduct of speech and respiration and turning it into oxygen and cleaner, filtered air.
While there is much to be discovered in terms of how plants interact with the world, there is no doubt that taking care of them can certainly feel like an intimate symbiosis.
1. Klaus Seeland, and Mihir K. Jena, "Knowledge Systems: Indigenous Knowledge of Trees and Forests," In Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures (Springer Netherlands, 2008), 1195.