I have a Japanese privet that has turned into a 30-40 foot tree next to my patio. How can I get it to stop blooming and dropping its flower and seeds onto my patio? Is there a hormone or something that I can use to regulate plant growth, similar to what is given to olive trees to stop them from producing?
There is a product called Florel which is an organophosphate pesticide that has been used to regulate plant growth. The active ingredient is Ethephon which has some health concerns, as described by the Environmental Protection Agency.
Florel was described as an alternative to the toxic chemical, NAA (Naphthalene acetic acid) which has traditionally been used to thin fruit, in an article in Arboriculture, by Harris, Clark and Matheny, 2004, p. 403). However, Florel is still a toxic product and overuse can damage your plants.
Another (non-toxic!) option would be to remove the privet and plant something which will not interfere with your enjoyment of the patio.