The Superthrive Test

[Ray]

I did the same thing once - SuperThrive, my own formulation, and nothing added to Dyna-Gro "Grow" formula at a constant rate, applied to 50 plants each of Phalaenopsis Lemforde Novely and Oncidium Sharry Baby 'Sweet Fragrance' AM/AOS - 300 plants in all, purchased in flats from a local wholesale grower. The plants were all together on the bench in the greenhouse (oncids in a brighter spot, obviously), and watered on the same days.

After 6 months of growth, there were still bell-curve distributions in the leaf spans of the phals, and height and number of growths in the oncids, but in both cases, those plants receiving the growth hormones were statistically significantly larger on average than those that did not. There was an advantage for my own formulation, which had humic acid, kelp extract and a few other ingredients over the SuperThrive, but it was not enough better to claim that.

[Bayard]

Chris - Experimentation is great! Don't be discouraged by the comments - I'm sure we're all trying to be helpful.

I agree with Frederico about the sample size being too small. The reason being that any effect seen may be due to chance alone.

Terri makes a very important point about using identical plants (clones). Sister plants are recombinants (not genetically identical), and may respond to your treatment in different ways.

Ramon is correct about not needing to blind yourself as to which plants are receiving the treatment. However, Frederico's caution about bias is warranted - you may feel that the treated plants are growing and flowering better.

How do you minimize that bias? Quantify! Measure size, weight, age at first flowering, root mass, etc. in both groups of plants.