Salix integra ‘Hakuro-nishiki’ Dappled Willow
Every season, there have been more questions about the care of ‘Dappled Willow’ shrubs and trees than any other subject. I will try to answer all those questions.
Finding complete information has been difficult in the past, to say the least. I first took an interest in the ‘Hakuro-nishiki’ willow shrub about ten years ago and at that time, a great deal of research produced very little information. Until recently, the information was incomplete and conflicting in some cases. But there are over 300 species of trees and shrubs in the willow family, many species and cultivars being difficult to identify and often mislabeled even in field studies. Apparently inaccuracies in Salix identification and nomenclature has been long standing, and the clarification of cultivar names and information has begun in recent years. The widespread use of the variegated dappled willows as well as other dwarf willow forms has encouraged some accurate collection of data, but it still seems to be scattered among many sources.
General culture information specific to the Salix integra ‘Hakuro-nishiki’ Dappled Willow:
‘Hakuro-nishiki’ is synonymous with ‘Albo-maculata’, also commonly named ‘Dappled Japanese Willow’ or ‘Variegated Willow’. It may also be marketed as ‘Fuiji Koreangi’, ‘Fuiji Nishiki’ or ’Albomarginata’. It is one of the smaller members of the family, grown as a small tree form or large shrub.
Delicate catkins, which are a yellowish pendant, appear in early spring, usually April, just before the leaves unfurl. Willows tend to leaf out as much as 4 to 6 weeks before most woody plants. Foliage is deciduous, emerging pink in spring and maturing to variegated creamy white and green, giving the foliage the dappled appearance. The leaves are delicate oblong shaped, up to 4” long. Leaves eventually turn yellow in fall and will drop quite late, perhaps October or November. Stems turn red in winter, continuing the colorful interest for your landscape or garden. Best foliage color is achieved in cooler summer climates north of zone 7, making the dappled willow an ideal choice for northern and midwest gardens. Pruning will encourage more colorful foliage, as it results in new growth. Pruning may also improve the red branch color for winter, as the newest growth is the reddest. In the coldest regions, zones 4 and 5, only the new growth will turn coral red. The entire length of the branches will turn coral and red in warmer climates
Salix integra ‘Hakuro-nishiki Dappled Willow’, as well as other dwarf shrub willows, are available as a tree form. These are grafted to a compatible, strong and straight growing, upright willow trunk. The growth structure of the dappled willow and other grafted dwarfs is not strong or sturdy enough to prune to tree form. Any shoots from the trunk or roots should be removed as quickly as possible. They can eventually overtake and choke the grafted top if allowed to grow, and of course will not produce the variegated foliage of the graft. The grafted portion, the tree top, can be pruned as desired when dormant, in late winter or very early spring before any new growth has begun. Continued shearing through the season will encourage constant new growth to maintain the colorful foliage and the desired form
Grow ‘Hakuro-nishiki’ in moist, fertile, well drained soils. I will tolerate poor soil, somewhat sandy soil or clay soil but may not produce ideal growth and color. Dappled Willow trees and bushes will thrive in moist soils, but will tolerate drier conditions once established better than many other willows. It will also do fine if the soil is occasionally wet. Do not over water, just try to maintain a regular water schedule by supplementing rainfall. And do not let your willow dry out completely between waterings for best health. Make sure your dappled willow receives consistent water in its first year while it establishes a good, deep, root system. It will also want consistent water during its spring growing season. Dappled willow will tolerate salt well so ‘Hakuro-nishiki’ is a nice choice for street and boulevard ornamental trees. A slightly acidec to alakline pH is preferred, from 5.6 (acidic) to 7.8 (mildly alkaline). Although willows are somewhat adaptable, a combination of adverse conditions will be detrimental to the plants health. For example, prolonged heat, drought and compacted clay soil can be damaging.
Dappled willow trees and shrubs will grow well in full sun, part sun or part shade. Best color is produced in full sun. But in zones with hotter summers, the dappled willow will not tolerate prolonged heat. It is best to plant in part sun or part shade and water weekly where summers are long, hot and dry. Plant your willow in very early spring before the earliest plants have leafed out, or in mid to late autumn when the soil is still warm but the air temperatures have cooled. The tender young shoots of a dappled willow seem to be a favorite of rabbits, so you may want to cage in your new plant with chicken wire to prevent nibbling. Once the willow is established and growing rapidly a little nibbling won’t be a problem.
Growth habit of the dappled willow shrub when young is upright, and outward in all directions. As the plant matures, branches will arch gracefully. It is quite elegant with the drooping branches, delicate looking variegated leaves, and dangling catkins. It is almost a shame to shear back the elegant foliage just to produce more colorful growth. You may prefer to cut back only several branches to about half or more to maintain the lovely form and still produce new colorful foliage In ideal conditions the mature height of the dappled willow shrub will be about 10 feet. Generally, projected growth reaches 4-6 feet in height. ‘Hakuro Nishiki’ is a little slow to establish, but then grows quickly at a rate of 12-18’ per year.
‘Nishiki’ willows take to pruning and shearing very well, to either promote good color or maintain a manageable size. Pruning should be done while dormant, in either early winter or VERY early spring before catkins appear and any growth begins. You may hard prune it down to about 12” every few years, which will produce a lot of regrowth and a very dense plant. If you prefer a more open and natural form, simply remove up to one third of the branches down to the ground each year or two. By thinning rather than shearing you will have an 8-10 feet tall and wide, elegant fountain of gorgeous variegated foliage. Or shear as needed to maintain size, or every 4-6 weeks to produce new colorful growth.
Eventually your dappled willow (shrub form) will develop thick central branches that become trunk-like, particularly if you are not pruning hard every year. The old trunks no longer turn red in winter, but do produce many, many branches that turn red. Growth will be dense to the ground, or you can remove branches up a length of each trunk, resulting in a multi-stemmed sem-tree form. Maintenance pruning is generally necessary as twigs develop up the length of the bared trunks. If there are too many main trunks, a few may be pruned out completely depending on the form you desire.
Fertilize dappled willow with a general purpose fertilizer very early in spring before any growth begins. Somewhat heavy fertilization will help maintain its’ foliage color, but don’t overdo it. Just be sure to fertilize each and every spring, being somewhat more generous than you would for other low maintenance shrubs.
The beautiful foliage is best set off against a dark background. For a striking display, plant beside or in front of deep purple foliage plants such as a ‘Black Lace’ elderberry or Purple Smokebush. Japanese willow is an excellent choice for a specimen plant in a large open space or near a water feature, hedge, screen, or windbreak. They will thrive in low areas that are generally more moist. Dappled willow will also do a very nice job of erosion control on slopes and banks. When sheared frequently to maintain size, the bush can be well used as a bed or border plant, or as a foundation planting. ‘Hakuro Nishiki’ will also do well in a very large container, as will other dwarf willow shrubs.
The very large tree form species willows have not been recommended for home landscaping due to their invasive, water seeking roots and weak wood. The root systems, which are excellent at seeking out moisture, can be particularly damaging to septic systems. The root systems of the dappled willow and dwarf shrubs, although well developed at maturity, do not compare to the size of a full size willow tree. The tree form ‘Hakuro-nishiki’ has been grafted to the trunk of another willow variety, and therefore will have a larger, more extensive root system than the shrub. Although there is little information available regarding damaging roots of the trunks used for grafting, these grafted tree forms were developed specifically for use in small home landscapes. It is highly doubtful that a trunk would ever be used from one of the very large willow trees that can be so damaging to septic tanks. Willow roots in general grow very fast, just like the willow plant. They can grow several feet per year and will usually spread equal to their height (a mature ‘Hakuro Nishiki’ may reach about 10 feet). In general, willow roots are invasive and can exceed the width of the tree’s branches as much as 3 to 4 times. But again, that refers to the large tree form willow. If you have a septic system and are concerned, why stress? Plant your grafted tree in a very large container, or at least at a great distance from the tank and pipes.
All willows, the Dappled Willow shrubs and grafted trees included, are susceptible to disease problems which include blight, crown gall, fungus, root rot, cankers, rust, Willow Scab, leaf spot and powdery mildew. May also be afflicted with insects including aphids, scale, borers, lace bugs, beetles and caterpillars. If your willow has been affected by insect or disease, or winter injury, remove all affected branches. You may severely prune out all damage, leaving very little healthy plant if necessary. The problem may be overcome by the complete removal of afflicted branches. Thinning out a third of the oldest branches to the ground every year or two may reduce problems, as older wood is more susceptible to disease and pests.
The family of willow is susceptible to a long list of insects and disease but they are not necessarily particularly damaging much less fatal to the plant. A few of those may specifically be common for the Dappled Willow.
- Anthracnose diseases are fungi the can cause defoliation (leaf drop) to several types of trees, including the willow. The damage usually occurs after cool wet periods during bud break. A single attack will generally not be harmful, but yearly infections will definitely reduce growth and may contribute to the demise of the tree.
- Rust causes small brown powdery areas of fungus on leaves and stems.
- Aphids leave a sticky sap on the leaves, which can then be afflicted with a black sooty mold. A serious infestation will leave the plant vulnerable to other pests and disease. The aphids are usually small fat green insects, about 2mm long, but may also be black, yellow, pink, or brown.
- Caterpillars eat the leaves, quickly leaving an unsightly plant.
- Leaf beetles strip the tissue of leaves, leaving leaf veins exposed. There are various beetles that attack willows (and poplars). They are small, ‘metallic’ blue, brown or brassy and about 4-5mm long.
- Sawflies larvae eat leaves, causing extensive damage. The adult is up to 10mm long with 2 pair of wings and dark bodies and legs. They may look like flying ants.
Dappled willow can be propagated from softwood or semi hardwood cuttings. To produce new plants, just plant 8” cuttings of stem without leaves into consistently moist soil in a small pot or nursery bed, they will generally root easily. When the roots become visible through the drainage hole in the pot they are ready to plant in the ground. Willows root fairly quickly, and cuttings potted in October should be ready the following spring. Full grown dappled willows also transplants quite successfully. A large plant should be cut back to about 12” in very early spring or late Autumn, then moved to a new planting hole.
Salix integra ‘Hakuro-nishiki’ Dappled Willow is hardy in zones 4-9. However particularly cold winters in zones 4 may cause loss of much of its variegation the following season. Shearing and fertilization will help to regain the colorful foliage. Since the dappled willow is hardy up to zone 4, you should not need to do anything special to winterize your dappled willow. Do follow standard practices to winterize shrubs and trees in cold climates: Water regularly and thoroughly in autumn to allow the plant to take in as much water as it needs, it will naturally decrease water intake as freezing weather approaches. And do NOT fertilize after about mid august. Fertilizing will encourage new growth, which may be damaged by freezing temperatures.
When you do prune your dappled willow, take some of those beautiful branches inside for a fresh arrangement. They are quite lovely in a bunch on there own, but also are great as filler and to add height in a vase with other cut flowers and branches. Put a few dappled willow branches in a vase with delphinium or lupines for a striking arrangement.
That should cover the more general questions about the ‘Hakuro-nishiki’ . Some questions are more specific to variable conditions that may affect growth.
My dappled willow seems dry even though I water, the leaves are drying up.
Most likely it IS dry. Dappled willows need consistently moist soil without being wet. Depending on soil conditions and weather, you may need to water weekly. Do not water lightly and frequently. Give it a good soaking, weekly if your soil is not moisture retentive or sandy, and if it is hot and dry. Every 4 or 5 days if the conditions are severe, less often if the conditions are less severe, but try not to let the soil dry out.
Can I overwater my dappled willow? What are the symptoms?
Symptoms of over watering generally begin with yellowing leaves. If the wet conditions persist, the leaves will begin to drop. Unfortunately, the symptoms of overwater, drought stress, and root rot fungus can be very similar. They all typically begin with yellowing leaves, then leaf drop, and eventually limb dieback. Poke into the soil, and if it feels moist, stop watering until the soil begins to dry quite deep. Then water generously, but do not water again until the soil begins to dry. If your willow begins to improve, over watering was likely the problem. If it has not improved, wait as long as you can stand it for improvement. Often the best thing for a sick plant is to do as little as possible. If the condition worsens, the problem could be one of the many diseases that afflict willows. Take a few close up, clear pictures, and a few freshly cut branches to a good local nursery to see if they can diagnose the problem. One last possibility, did you fertilize in the spring? Dappled willows do best with a generous dose of general purpose fertilizer in spring. Yellowing leaves, usually with no other symptoms, can be a lack of fertilizer.
Will pruning keep the roots on my ‘Hakuro-nishiki’ small?
Not substantially, I know the standard rule of thumb is that the root spread will generally be at least as large as the branches spread, and for large willow trees the root spread is much greater, but keeping top growth small will not affect the root system much. I expect that if you keep a 10 foot shrub pruned to a consistent 2 feet, the root growth will somewhat retard just because the plant does not need so much root. If you are concerned about the notorious willow roots tapping into septic tanks and water lines, see above.
When should I plant a Japanese Willow?
The best time to plant is early spring or autumn when the weather is relatively cool so the plant and soil do not dry out too easily. Planting anything can cause some stress, so try not to add to it by planting on a hot, dry, or windy day. Most shrubs and trees can be planted anytime, even midsummer, with proper care. But those that don’t tolerate the long hot summers even after established will struggle. If it is already summer, wait until fall or spring to make it easier on the plant, AND you!
Can I transplant my dappled willow?
Yes, they tolerate transplanting quite well. Take note of when best to plant in the previous question. If your shrub is already quite large, reducing the size will make it easier to manage.
My variegated willow is reverting to all green - the foliage on a few branches is completely green. Is there anything I can do?
Many of the plants with variegated foliage can begin to revert, particularly the variegated Norway Maple. In the case of a dappled willow, there are several thinks you can do to reduce the occurrence. First, the colorful variegation is most prominent on new growth - frequent pruning will encourage new growth. Next, best color is achieved in full sun. Unless you live in a hot zone with long dry summers, do plant in full sun. And, fertilizing will also encourage good color. Be sure to fertilize generously each spring with a general purpose fertilizer. If your soil is extremely poor you may want to fertilize again 6-8 weeks later. And finally, prune out branches that have all green foliage. The all green limbs always grow the most vigorously, and if allowed to continue will overtake the variegated limbs.
Are the dappled willows susceptible to disease?
This is one of the areas that information is sparse related specifically to the ‘Hakuro-nishiki’. The general species of willow is susceptible to many different diseases and insects, some are known to specifically affect the Dappled Willow, as noted above. Whether or not the ‘Hakuro-nishiki’ is an “improved” (by human intervention, hybrids) cultivar I am not sure. Generally a hybrid will take the best characteristics of different plants to develop in improved variety, often improving the disease resistance. The Salix integra ‘Flamingo’ is an improved variety of ‘Hakuro Nishiki’, though not by hybridization. The ‘Flamingo’ has been propagated from a whole plant mutation that occurred naturally. It has a more upright and spreading growth habit; smaller and thinner leaves; thicker stems and sunscorch resistant leaves; and more red color in young leaves and branches. There is no difference in the disease resistance. If your dappled willow is ailing in some way, investigate the disease and insect possibilities noted above.
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