Bay bush, looking very sick

I've had a container grown laurus nobilis (bay) for about 8 years, but this year it's looking very sad. It's on a 4th floor terrace, but pretty sheltered. The leaves are going yellow or brown and dropping off. It was fine earlier this year. What's happened? Is it just too old, or have the roots rotted?

I like it because it's tall enough to block my bedroom window from the eyes of the flat-dwellers opposite so, if it has to go, I need a replacement.

Any advice very much appreciated!

 

Jervis, how often are you watering it, and, more importantly, what are you feeding it with, and how often?

 

Jervis

I've kept the same bay tree in a pot for about 30 years. It's been the same height for about 20 years but its trunk is getting fatter as the years go by - a sort of supersized bonsai! Bays need a careful balance of food and water plus a sensible balance between the size of the root ball and the size of the head of the plant (assuming it's a standard lollipop shape). Do you prune it and check its roots each year? Is it getting enough sun?

 

The same thing is happening to my Bay in a pot at the mo. We are going to give it a good feed.

I also have some Leylandii in pots and the same thing is happening with them.

 

Rose, both the Bay and the Leylandii should be fed with ericaceous fertilizer.

 

Many thanks, Daitheplant.