I Have 9 Clethra Anifolia’s In Garden With Hydrangea. I Prune Back The Clethra In Late Winter/early Spring To Control Size. I Don

Question

‘t et many blooms, only at bottom They are in sun to part sun locations. Any idea why they don’t bloom at the top? They have lots of green. Also, is it ok to prune back the new top green growth in summer after they have bloomed make them look neater?

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Answer 1

This could, likely, be due to low phosphorus and potassium in soil. You can test and amend as necessary.

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm.

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/amend-soil-around-existing-plants.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/too-much-nitrogen-soil.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/phosphorus-plant-growth.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/plants-potassium.htm

A far as pruning goes- This should be done in Spring. A summer pruning may lead to stress that may hinder growth. This article will help to care for it:

https://www.gardeningknowhow.com/ornamental/shrubs/summersweet/summersweet-plant.htm