I\’ve Five Horse Chestnuts, About 20 Yrs Old, And They\’ve Never Flowered. Why Might This Be?

Question

They are in a sunny position, though planted rather close together. They appear healthy.

Answer 1

You don't specify your area, but it could be that they are outside of their native region. Otherwise, there are a few diseases that can affect the trees. This article will help:

https://www.gardeningknowhow.com/ornamental/trees/horse-chestnut/common-horse-chestnut-issues.htm

Alternatively, the soil pH or nutrition can be out of balance. These articles will help:

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

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