How to Grow Globe Willows
The globe willow (Salix globosa, Salix babylonica "Navajo" or Salix matsudana "Navajo") is not a only a non-weeping willow, but -- with its upraised branches and lollipop shape -- is practically a jubilant willow. What might not make you giddy, however, is the tree's propensity for trunk and branch damage from winds, as well as its vulnerability to a host of diseases and pests. On the plus side, globe willows are prized for their preference for moist soils and their corresponding ability to tolerate occasional droughts. If you're determined to grow the globe willow, which prefers U.S. Department of Agriculture hardiness zones 5 to 9, give it the care it needs to help it withstand the climate.
Apply commercial tree wrap around the base of the trunk in late fall for the first two years after planting a globe willow. Tree wrapping prevents sun-scald during winter. Secure it to the tree so the black side faces the tree and the exterior portion is white.
Remove the protective wrapping in early spring.
Mulch the tree in a wide circle around the tree's base in a layer about 3 inches deep. This step suppresses weeds and keeps a safe boundary between fertilized grass and tree. Fertilized soil can be problematic for globe willows during the fall because it causes "greening up," or pre-winter growth in the trees. This new growth makes the tree more vulnerable to winter damage.
Look for branches that have split at the crotch of the tree or which appear discolored or oozing. Damaged branches may show yellowing or drooping foliage, or have a hollow sound when you tap them. Globe willows are susceptible to a disease called frothy flux, believed to be encouraged by damaged tree tissue. The disease not only endangers the life of the tree, but makes the globe willow more hospitable to tree borers, which also threaten tree health.
Remove damaged branches from the tree when you spot damage. Use pruners, loppers or a saw to cut the branch as close to the trunk as possible. For large limbs, make one cut halfway through the branch from the branch's underside, then move saw a few inches higher and saw cleanly through from the top to bottom. You may need to hire a tree service for large limbs or secondary trunks.
Fertilize globe willows in the spring with a balanced fertilizer, such as 8-8-8 or 10-10-10. This feeding helps encourage healthy tree growth and reduces susceptibility to such diseases as Cytospora canker. Broadcast the fertilizer on the ground under the outer edge of the tree's branches. Apply 1 1/2 to 2 pounds of fertilizer for every 100 square feet. Use a commercial push fertilizing cart or a large tin with holes punched in the top for even application. Water the area so the fertilizer dissolves in the soil.
Monitor the globe willow's trunk and branches carefully for signs of insect damage. If you identify specific pests, such aphids or tent caterpillars, consult your extension service for treatment methods that are either organic or low in harmful insecticides. Spray aphids with a garden hose set to a forceful spray to knock them off the tree.
- Compacted soil can be problematic for globe willows. During planting, loosen soil around the planting area and add sand, or other humus-like matter, if the soil is extremely compacted.
- When planting, set the globe willow in the hole so the tree will be sitting 2 to 4 inches higher than the surrounding area. Add extra soil to the bottom of the hole if you need to raise the crown above the soil. This encourages proper drainage, helping to avoid root rot.
- Because globe willows are especially prone to wind damage, staking the trees can be helpful. Set two stakes on either side of the newly planted tree and attach them to the tree with nylon strapping adjusted in figure-8 configurations.
Ellen Douglas has written on food, gardening, education and the arts since 1992. Douglas has worked as a staff reporter for the Lakeville Journal newspaper group. Previously, she served as a communication specialist in the nonprofit field. She received her Bachelor of Arts from the University of Connecticut.