Gardeners with their ears to the ground may have heard this advice lately: Grow up.

Yes, many gardeners already add variety and balance to their gardens by breaking up the flat, horizontal planes with fences, arbors, trellises and perhaps an old shed or garage, all covered with climbing vegetation.

But now the notion of even more intentional vertical gardening is taking root. In fact, a whole subset of gardening is being propagated in spaces well above the soil.

For those who haven’t caught on to vertical gardening – that is, growing up rather than out – here’s a chance.

One of the world’s leading proponents of covering walls and other upright structures in plants will present a workshop on the subject on March 5 at the Davidson Horticultural Symposium.

Dr. Noel Kingsbury of the landscape department at the University of Sheffield, England, will discuss what works and what doesn’t and how vertical planting can support biodiversity and improve the environment, especially in urban areas with space limitations.

Kingsbury has written more than 20 books on gardening and is known for his advocacy of what’s called an ecological or naturalistic approach to designing with plants.

His last book, “Planting Green Roofs and Living Walls,” co-authored with Noel Dunnett (Timber Press, 2008), makes the case for including green plants in every aspect of urban design, using vegetation to visually soften hard materials as well as to help heat and cool buildings.

As vertical gardens bring nature into the city, they also help rid us of air pollution and some other negative environmental factors of urban living, Kingsbury said. They are especially valuable for wildlife habitat in gardens, he said.

The obvious way to make a vertical garden is to plant climbers in soil at the base of a building or support structure.

Yet, there are gardeners who see a canvas on every blank surface, inside and outdoors. That has led to a more ambitious approach: the living wall.

The field of living walls, often called green walls, has vegetation growing in or without soil.

Queens University of Charlotte installed a living wall in December at the new Rogers Science and Health Building.

The wall – designed to be inspirational, functional and educational – uses vegetation to reduce energy consumption by keeping the building cooler in the summer and warmer in the winter, according to Reed Perkins, professor of environmental science.

The green wall at Whole Foods Market at SouthPark grows indoors, bringing nature’s beauty in, said marketing representative Jennifer Wosniak.

In the orchid pavilion at Daniel Stowe Botanical Garden in Belmont, the living wall thrives without soil, thanks to hydroponics, the technology of growing plants in a nutrient solution. The wall presents nature as art.Green walls might not be practical for a novice or occasional gardener because they can be demanding and expensive.

The grower should be comfortable with plant selection, hand-pruning and grooming, timed drip irrigation with recirculating water, liquid fertilizers and, when needed, supplemental lighting. All of these are necessary for keeping a wall healthy, said Brad DeHaven of Oasis Plantscaping, who maintains the Whole Foods wall.

Indoor greening, especially with climbers, is a new area of enormous potential, especially as more people spend more time inside, Kingsbury said.

Given the scale of many modern buildings, climbers and facade-greening technology have a major role to play in removing pollutants and raising humidity levels, he wrote in a chapter on living walls. Green walls are good for the psyche, as well.