Have used it on plants in pots in the back garden. Seemed to do the job ok.
The way that plants feed from soluble fertilisers like this is exactly the same way they feed from nutrients in the soil.
However, there are other things to take into account. The processes involved in making the stuff use energy and deplete earth's resources, and they contribute nothing to the structure of the soil. The more expensive soluble fertilisers do contain a wide range of trace elements, but by adding a wide range of things to the compost heap, you will get the same effect. It may be harder to get the range of nutrients required into a sandy or silty soil, but in my opinion anyone with a good clay soil and good composting methods doesn't really need to use soluble fertilisers.
