Q.Fennel grown near other plants
I’ve read that Fennel is allelopathic to other plants and can actually kill other plants when planted near it. Is it true? If it is, how far should it be from other plants to prevent damage?
Also, if it can ‘kill’ other plants, can it kill full grown trees too?
Thanks

It's true, Fennel does not have many friends.
Fennel is allelopathic to most garden plants, it inhibits growth and causes bolting or even can kill plants.
You can grow in a container quite easily.
I plant Fennel in with my perennials, the Swallow Tails love it!
https://www.gardeningknowhow.com/edible/herbs/fennel/growing-fennel.htm