Is it worth using Hormone Rooting Powder?

Kristen - I did a little calculation, which seems to say that if you have a 1 litre bag of air there is only enough C02 in it to support 0.4 grams of new plant growth. During the 10 days or so my Salvia cuttings take to root, they often grow several small leaves, not to mention flower buds and even flowers. I used to cut the buds off as they formed, but they grew more so quickly that nowadays I don't bother. I let the cuttings flower if they want to, and they often do. Without cutting off the new growth and weighing it, my feeling is that in 10 days they can put on quite a bit more growth than 0.4 grams.

The calculation is :-
volume of C02 in 1 litre = 1000 cc x 0.039/100 = 0.39 cc (0.039% by volume)
weight of C02 in 1 litre = 0.39 x 1.5 = 0.585 grams (CO2 is 1.5 times as heavy as air)
weight of carbon = 0.585 x 12/44 = 0.1595 grams (atomic weight of carbon = 12, atomic weight of CO2 is 44)
weight of plant material = 0.1595/0.4 = 0.3988 ( carbon makes up 40% of plant weight)

 

I root a wide range of plants from cuttings ,and in general never use rooting hormones and have good success rates .
I feel the key is taking cuttings at the right time of the year (not always possible I know ) and good compost drainage ...
This is not to say don't use it ..it's trial and error to find which suits your needs ..there are also other factors to take into account when rooting cutting so hormones are only one factor ...

Dave

 

Sorry, haven't had time to put my thinking cap on Peter. I've not forgotten about this thread, and I appreciate your figures - thanks. Definitely something to consider. The A-Level Chemist will break up in a few weeks so I'll give it to her as a holiday project to research.

Yours ever, Scrooge