I have two pagoda dogwoods in large planters in a rooftop garden, planted in summer 2017. They get a lot of sun and are pretty sheltered, as they are beside an 8-foot wall. The soil is kept moist but far from wet. Right now, they have plenty of leaves, which look quite healthy, but hardly any blossoms and all of those are on the topmost branches. Why are there not more blossoms? Should the trees have had a lot more fertilizer (worm compost) in the fall? Should I try that this fall and hope for more flowers in 2021?
Thank you for your question.
Pagoda Dogwood is best grown in moist, slightly acidic, organically rich, well-drained soil and enjoys full sun to part shade.
As recommended in a previous post, mulching in the spring and fall, applying compost or manure and a gentle pruning in late fall or winter to remove deadwood are good practices to help sustain your trees.
Dogwoods have a very dense, fast growing root system which can make them a challenge for containers. It may be that the plants have become root-bound and may require you to prune the roots back. You may find the following link to the article “Growing Dogwoods in Pots – How to Grow Dogwoods in a Container” helpful.
https://www.gardeningknowhow.com/ornamental/trees/dogwood/dogwoods-in-container.htm
Good luck with your beautiful trees.