Bio Gold is good stuff...but not for every species.

I use it on pines and junipers along with Miracle Grow for Azaleas. 0-10-10 in spring and fall.

On elms I use Bio Gold.

On maples I use rapeseed cakes.

On others I use Bonsai Pro.

It's all basically the same depending on its ratio. Some are 10-10-10. Others 5-10-5. Others are 20-20-20. If you like doing the work, use any maricle grow type fertilizer according to instructions with minor adjustments depending on time of year and plant vigor, or use a slow acting, soil addition fertilizer. Do not use maricle grow types (the type you mix with water), in ratios more than what are on the directions. If anything, use them half strength or quarter strenght and administer more often that directed. Plants need the three basic elements that are in most fertilizers. More or less, all fertilizers are more or less the same. Some are slow acting and don't wash away, some are fast acting and will wash away after a few good waterings.

Don't use miracle grow types on Japanese maple. It can cause leaf burn. If you use the osmacote types you should know that it is more a temperture release than a time release. It may only be feeding your trees for a short period of time in the northern climates.