Like so many fads, vertical gardening has become trendier than it should be. It certainly has practical applications, and is very appealing in the right situations. However, in the wrong situations, it can be more problematic than it is worth.
Vertical gardens can shade and insulate exposed walls, but really do little more than strategically placed shade trees, large shrubbery or even trellised vines can do in that regard. The disadvantage of vertical gardening is that it can hold moisture against the affected walls, and can promote rot if the planters are not installed properly. Planters over windows or decks drip just like any other planters do, staining or dirtying whatever is below. Only free-standing vertical gardens (that are not attached to a wall) or those on concrete walls that are not susceptible to rot will not cause such problems.
Water-borne pathogens (diseases that disperse in water) can proliferate more in vertical gardens because they get carried with the natural flow of water from top to bottom. Wherever any such disease gets established on a vertical garden, it will likely get carried to everything below. In the ground, such diseases spread more slowly since they travel only as far as water flows or gets splashed.
The obvious advantage to vertical gardening is that it makes it possible to grow many more plants in very limited space, which is excellent if there is no open ground for vegetable gardening. It can also be a great way to display plants like orchids and certain bromeliads that are more appealing if they hang from above. Staghorn ferns cling to walls naturally.
Another advantage is that vertical gardening can be so aesthetically appealing and unique. Vertical gardens of small, densely foliated succulents hung like tapestries to adorn exterior walls are so much more interesting than simple vines or shrubbery used to obscure such walls. Northern exposures that are too dark for most plants can be adorned with ferns.
Flower of the Week: Gazania
The most familiar of the gazanias are the trailing types commonly appreciated as groundcover. They are rather shallow, but dense enough to prevent most weeds from getting through. Their yellow or orange composite (daisy-like) flowers bloom initially in spring, and then continue to bloom sporadically as long as the weather stays warm into autumn. Some trailing gazanias have interesting silvery foliage.
Clumping gazanias do not spread efficiently or thoroughly enough to be practical as groundcover over large areas, but bloom a bit more profusely with bigger flowers in shades of yellowish white, light yellow, bright yellow, orange, brownish orange and brownish red. The foliage gets a bit deeper to form irregular but dense low mounds. Clumping gazanias can be lined up as an informal border around blooming annuals or perennials, or incorporated individually into mixed urns or vertical gardens.
Gazanias are not too discriminating about soil quality or frequency of irrigation. They need only good sun exposure. Trailing gazanias are rather easy to propagate by cuttings made from scraps from pruning around the edges. Clumping gazanias do not get pruned as much, but are easy to propagate by division from dense clumps.
Horticulturist Tony Tomeo can be contacted at 408.551.9931 or lghorticulture@aol.com.
