We use a catchall term, weeping trees, to describe trees that are pendulous in nature. But so many other adjectives can be used to describe them. Some cascade; some drop like a curtain of rain, straight to the earth; others puddle and leapfrog along the ground; and a few stretch out as if they have wings and look as though they could take flight. People seem to either love them or hate them. The latter find them sad looking or depressing while the former find grace and elegance in their forms. I have always loved them and my first crush was the elusive weeping katsura (Cercidiphyllum japonicum ‘Pendula’). I met the tree during a walk with my dendrology professor at the Indiana-Purdue Universities campus in Fort Wayne, Ind., and it was love at first sight.
The katsura was old enough to have branched out and begun the cascading effect reserved only for older specimens. The bluish green leaves had a luminous quality and fell like rain from the arching branches. I tried to find one for myself but alas, this tree was much more difficult to find in the early 80s, so I settled instead for a weeping mulberry.
Since then I have planted or worked with many a weeping tree and become familiar with their habits, contributions, and yes, their faults. If I were to plant a weeping tree today, the katsura would still be at the top of my list, and the mulberry would somewhere near the bottom. Read on to learn why.
Ulmus glabra ‘Camperdownii’1
Weeping trees, whether deciduous or evergreen, are most often used as specimen trees. It makes sense to use them singly so that they can grow to a natural size and shape and be viewed without competition from other plants. That is not to say that a homeowner could not use a pair of them to flank a formal drive, ring one side of a pond with weeping willows or group a mass of skinny conifers such as weeping Serbian spruce to create privacy. But a grand weeping cherry, or a mature weeping hemlock is going to display best standing alone against a blank wall or on a lawn.
Select the site before you select the plant. This is difficult for most of us because gardeners tend to be impulsive, bringing plants home and then worrying about where to place them. But the space you have will dictate the appropriate kind of weeper.
An open lawn could accommodate about anything from a huge, mature weeping beech to the lumbering “hills” of a weeping spruce. A small lawn or tight space, however, needs a smaller specimen, perhaps a cherry or magnolia. A wall would be perfect for trees that send out arching branches as they mature and begin to cascade like a fireworks display. Naturally, you will need to consider the soil type and exposure just as you would for any plant.
How They Grow
When it comes to maintenance, it helps to understand how they grow. There are two kinds of weeping trees — those that form pools and mounds along the ground and those that are grafted onto tall, straight trunks called standards. If you are looking for plants that arch and creep along the ground, then you will want naturally weeping or pendulous plants that are growing on their own roots. Dozens of weeping forms of evergreens suit this purpose. But if you want something that stands vertically and weeps down around a single trunk, you need a grafted tree.
Trees weep due to a genetic mutation that causes the branches and stems to be soft, more pliable and able to hang down. To elevate the weeping stems, many trees are grafted onto a related, upright rootstock. Because the mutation is not always stable, some plants will revert to the standard form and send up perfectly strong branches that stretch upward. These must be pruned out annually. Occasionally graft incompatibility can cause a tree trunk to outgrow the weeping top or vice versa. When this happens, the tree must be removed.
Some weeping trees that are grafted onto standards are so vigorous that they put out too much top growth and need constant pruning to keep them from looking like an inverted umbrella. And this brings us back to that mulberry. I’m sure the tree has its cheerleaders, but it is the most vigorous of this group and does need constant attention. The weeping birches and willows run a close second in vigorous stem production.
Plan on waiting a while for your weeping tree to come into its beauty. Most can be a bit awkward when they are young, and some growth spurts may make them look a bit too asymmetrical until they fill in and mature. I planted a small 5-gallon ‘Elizabeth Lustgarten’ kousa dogwood about four years ago. It is just now beginning to fill out a bit and bloom well. I am a big believer in planting small trees because they grow so well and eventually outpace their large, balled and burlapped counterparts, so the wait is worth it to me.
Snow Fountains® weeping cherry2
Weeping cherries are extremely popular but unhappily, one of the most difficult to grow successfully. The two problems most often encountered with these heartbreakers are overwatering and planting too deeply. They need good drainage and will not tolerate wet soil, and because they are top heavy, gardeners often plant them too deeply or mound soil up around them to keep them from leaning, thus exacerbating the water issue. That being said, they do need supplemental watering during periods of drought, especially when they’re young.
Cherries are also susceptible to an astonishing array of pests, including leaf blight, tent caterpillars, cankers and Japanese beetles. Good cultural practices are critical, such as cleaning up around the trees regularly, watering deeply, but never allowing standing water. Plant the tree high, with the root flare exposed.
Standard-sized weeping cherries such as Higan (Prunus x subhirtella ‘Pendula Rosea’) and P. serullata ‘Kwanzan’, which get quite large, will grow branches straight up from the crown. These large cherry trees, should be allowed to grow, only removing stems that appear below the graft. These upright branches will eventually arch and fountain down but may look awkward when the tree is young. Only the smaller-statured trees such as ‘Snow Fountain’ should be relieved of any upright branches.
The term weeping, when applied to many of the conifers, is misleading. Most of the spruce, hemlock and especially pines that are called weeping are more undulating, eventually growing into large hummocks of foliage that lumber or spread along the ground. They may seem like small, more or less upright plants in the nursery, but they will need some real estate as they mature.
Pruning a weeping tree can seem daunting, but just keep a few principles in mind. Always remove each stem or branch all the way back to its point of origin. Don’t leave any stubs or clip the ends off any branches. Trees have a hard time healing from this.
Keep the ultimate shape of the tree in mind as you view it and remove the stems that are going in the wrong direction of your vision. Keep stems that arch upward and outward like a cascade, and remove any that point inward toward the trunk, shoot straight up or straight outward.
Thinning is important for vigorous growers. Get in underneath the tree and remove crowded stems from the crown. Always follow the stem you are about to cut with your fingers to make sure you are removing the right one. I have another person give each branch a shake before cutting so I can stand back and see what we are removing and how it will look.
Weeping tree branches do not need to be cut when they reach the ground. With the exception of mulberries, they will stop growing when they touch the ground. With low, mounding evergreens, touching the ground will make the stem arch back up, forming the desired mounds of growth.
Grafted trees will have a graft scar just below the weeping branches. Remove any new stems that sprout below the graft scar as soon as they appear. Suckers at the base of the tree must be removed annually as well. Weeping cherries should be pruned just after they bloom in the spring. The branches will fork into two stems wherever they are cut, so keep this in mind when selecting which branches to cut.
1. Photo by Ed Lyon
2. Photo by Maria Zampini
3. Photo courtesy of Bailey Nurseries
From Chicagoland Gardening Volume XVIII Issue IX