The best times of year to plant hybrid willow trees are the spring.

Aug 13, Why are my hybrid willows losing their leaves so early? It's not anywhere close to Winter here in Sunny So Cal. This happened last Summer as well. They lost their leaves and then grew a complete set of new leaves.

That means your trunk diameter will eventually reach 30 inches for a mature tree.

But the purpose of having shade during the worst of the summer was sort of defeated, as they were bare in August.5/5(K). Oct 11, It is not a true evergreen. If you live in a geographic location that experiences all four seasons, then you will not get to benefit from the year-round evergreen natural barrier of the willow hybrid.

The two trees that make up this hybrid are both deciduous, so it will lose its leaves Estimated Reading Time: 10 mins. Diseases can cause willow trees to drop leaves early.

Fungal diseases cause galls to form, which are growths that encircle branches, eventually cutting off the supply of nutrients to the leaves. Willow scab causes cankers to form, which are areas of cracked, dead wood.

They can grow up to 75 feet in height when you plant them by themselves.

The cankers have the. Hybrid Willows are deciduous trees, so they will go dormant in the late fall to winter and their leaves will fall off. Hybrid willow trees also make a great fast-growing natural privacy screen – saving you thousands over installing a privacy fence!