Promix and PH

by Ken Cole
(Mississauga, Ontario)

Hi Doug

My understanding is that both Promix BX and HP have no need for PH adjustment. Is this accurate?

Another question which is more specific: Will a Hydranga (blue or pink) planted in a container stay blue or pink in Promix or do I need to make the necessary PH adjustment just like in the ground?

Thanks so much for all your time and effort and just for caring.

Ken

Doug says a good artificial soil will be slightly acidic. Container plants require more acidic soils than the same plant grown in the ground (a little arcane bit of knowledge picked up from 25 years as a grower but don't ask me why this is)

So you can grow a hydrangea in artificial peat-based soil just fine but if you want it to really go blue, you're going to have to acidify the soil even futher with some acid-plant food. (conteiner growing is one of the few times I'd recommend an aluminum sulfate type of plant-food product because it has been linked to plant death in the garden but is one of the few good ways to lower plant pH in container soil without wrecking the plants with application problems.