I've read on here that Orchids like Kelp/seaweed, and it's got me curious. I've not seen any orchid specific Kelp products, but I've got some pure, freeze dried kelp powder and I'm wondering if anyone knows if I could use in on my Phal orchid?
If so, what sort of concentration and how often would you recommend using it?
I wouldn't say that "orchids like kelp/seaweed", the more precise way of understanding this is, "many orchids like the nutrients and hormones present in kelp/seaweed".
You may use kelp/seaweed products for use in gardening for your Phals with no negative side effects.
I don't know the concentration to recommend because that depends on each product. When in doubt use 1/4 to 1/2 strength of what is recommended on the bottle for the time being and work your way up to the full recommended dosage by the company that produced the product.
Kelp or seaweed contains plant growth hormones. The positive effect it has on orchids is the production of more and larger roots. Kelp is a very mild product that doesn't contain anything that will burn the roots. To be on the safe side you can start off by using 1/2 the recommended dose. During the summer growing season I use the full recommended strength and I've never had any adverse effects.