Standards - flowering shrubs or woody vines trained to look like small trees - have never been in greater demand. Patio trees in which the plant's crown is at least 30 inches above the top of the container are especially popular.
The demand is so great, in fact, that some wholesale nurseries have shifted their production emphasis to meet it. At Hines Nurseries in Irvine, California, 10 acres are now devoted to growing patio trees versus just 2 acres for full-size trees, reports Felix Barron, field operations manager at Hines. Twenty years ago, that ratio was exactly reversed, he says.
The main reason for the surging interest in patio trees, says Barron, is the ever-shrinking size of Western gardens. The yards of newer homes, in particular, are often too small to accommodate a full-size tree, he says. But even the smallest courtyard has room for a patio tree, some of which can be maintained at 4 to 5 feet tall by pruning. Another contributing factor to their popularity is versatility: Patio trees grow equally well in a large container as they do in the ground.
At the same time, gardeners are learning to blend standards into their landscapes. Tree roses, for instance, don't have to look like isolated exclamation points, says Tom Carruth, hybridizer and horticulturist for Weeks Roses. They can serve as vertical elements in mixed borders or mingle in beds with shrub roses.
For all these reasons, patio trees are available in greater quantity and variety than ever (see below).
Prune to promote bloom
"Often and lightly" is the best pruning policy for all standards, according to Barron. Tree roses are no exception. "Hard pruning just encourages long shoots to form," says Carruth. Plants that flower almost continuously, like Paraguay nightshade (Lycianthes rantonnei), benefit from trimming as often as once a week. With shrubs that set buds once a year, like azaleas, wait until after bloom to shape.
Vigorous plants like bougainvillea occasionally need to be pruned hard. The nearly 40-year-old bougainvillea standard pictured above at Sherman Library & Gardens in Corona del Mar, California, is cut back by one-half to two-thirds every three to five years, according to John Bishop, manager of horticulture. The rest of the time, it is pruned lightly for shape. "If you want flowers, you have to keep pruning standards or your flower production will gradually decline," says Bishop.
Stake young plants
Standards are naturally top-heavy, especially when young. To keep their delicate trunks from snapping in the wind, support them with a sturdy wood stake or 1/2-inch-diameter galvanized pipe. As they mature, some plants develop trunks strong enough to support crowns. But if you live in an area with gusty winds, you might want to keep them staked indefinitely.
15 standard choices
You'll find many standards sold in 2- and 5-gallon containers. Tree roses usually come in 36- and 60-inch-high sizes.
Azalea, Southern Indica varieties
Cape mallow (Anisodontea hypomandarum)
Euryops pectinatus 'Viridis'
Flowering maple (Abutilon hybrids)
Gardenia jasminoides 'August Beauty', 'Mystery', 'Veitchii'
New Zealand tea tree (Leptospermum scoparium)
Paraguay nightshade (Lycianthes rantonnei 'Royal Robe')
Roses (floribunda, ground cover, shrub, and hybrid tea)