bonsai fertilizer

what is the best fertilizer for bonsai? Is superthrive ok or is miracle gro ok? Any in suggestions?

Superthrive is not fertilizer. It is Geritol for plants. Some people swear by it, but its value is questionable. It has never been tested scientifically, so we don't know if it's any good. On the other hand, if you want a nutritional supplement for your trees, seaweed extract is a proven winner.
The usual practice is to rotate fertilizers, to make sure your plants are getting everything they need. Fish emulsion is not recommended as a steady diet, but my plants like it once a month. Be sure to use a fertilizer with trace elements periodically. Miracle-Gro is fine, but it is high in nitrogen and might encourage lush growth, which is not what we want. Alternate with lower nitrogen foods, like rose food.
Iris

I like Miracle Gro (All Purpose) but I also have some MG for Rose, and Orchids I plan on rotating with the all-purpose later.

I buy something cheap and balanced N-P-K typically 20-20-20 and it works

hi,
it depends on what trees, how fast you want growth, your prefered soil mix and how busy you are really. I prefer virtually inorganic soil mixes & organic slow release fertiliser in my bonsai fertiliser bags and wherever possibe additional mycorrhiza to actually feed the tree properly. If you only have a tree or two and are busy an organic pellet like biogold will work well - releasing feed at every watering for 6-7 weeks. Once you have alot of trees biogold is a bit expensive so search for other similar things

cheers Marcus