Fish emulsion and kelp fertilizer, works pretty well as an all around fertilizer.

Worm castings are great

Thanks to both of you!

Funny thing abut worm castings.....
One day I got a small hand digger and dug down about 8-12 inches into the soil of my container grown trees to check the moisture level. I was really shocked to find a whole lot of earth worms crawling around in the soil on almost all of the trees!! I had to wonder what efforts it had to have taken for those worms to get into these pots. Some of pots are sitting on the grass in the yard which would make sense, but some of them are placed onto a concrete patio that the worms would have had to cross just to find an opening to crawl into--kinda crazy! Either way I am happy for the help from these worms as my trees are liking the free worm fertilizer!

Another suggestion to the good ones given here are Osmocote or Dynamite brand fertilizer...both are SAFE for containers, slow release and won't burn the roots if used according to directions.

I've used the red, green or yellow containers with great results. Home Depot carries some of them.

Here is a link that might be useful: Dynamite Fertilizer

Thanks pug!

Thanks pug!

EEK! Sorry about the double post. Has anyone ever tried the brown dynamite (Organic All-Purpose) fertilizer?