Auxins and plant hormones

[nickykinz]

Our biology students are doing plant EEI's this term and we will be using some plant hormones. We did this last year and I struggled a bit to work out the best concentrations to use. I tried to use the instructions on the website of the supplier but couldn't work it out. The students will be watering the plants with solutions so would like it to be fairly dilute otherwise we will get through a ridiculous amount. Also is it best to use the specialist indole acetic acid or would I be just as good using root strike powder and making solutions from that?
Last year the students didn't get good enough results to be able to tell if we did the right things or not (they didn't look after the plants very well or we killed them by giving too much hormone!).
Anyone who has successfully used IAA or any kind of auxin, I would love to get your opinions.