Opinion on Epsom salts for Phalaenopsis Orchids

[Orchid grower]

Hi there!

I am looking for your thoughts on using Epsom salts on phalaenopsis orchids. I've read it can help to flush out any salt buildup. I am also wondering if anyone had experience with using Cal-Mag as well? If I were to add any of these it would be in addition to my regular fertilizing routine. Does anyone have any experience with either of these? Or thoughts?? Thanks!

[Dollythehun]

Fertilizers, nutrients, epsom salts, kelp, MSU etc.

[fishmom]

Epsom Salts is magnesium sulfate, a salt. Magnesium is needed for good growth, but it is present in trace amounts in many fertilizers. Same with calcium. Take a look at the analysis for your local water, which should be available from your water company if you are not on a well. Large amounts of these minerals are not necessary.


It is easy to think that finding the right fertilizers and additives will solve problems with orchids, but they are much less important than proper light, temperatures, and watering. Concentrate on culture first, any basic fertilizer applied in dilute amounts will be satisfactory.

[camille1585]

Epsom salts are, as mentioned, a salt. Therefore I don't quite understand how a salt could flush out salt buildup. From what I could find online, people recommend Epsom salts to flush the buildup, then using unfertilized water to flush out the epsom salts... Flushing with tap water (or pure water if your tap water is high in TDS) is more than enough to remove salt build up. The general advice is to flush with plain water every 4-5 waterings or so, and that's more than enough, unless you have some very salt sensitive orchids.

[Ray]

@ orchid grower - please don't be looking to add, add, add to improve your orchid-growing. Magnesium and calcium are essential to plant growth, but might be sufficient in your water supply or current fertilizer, so be certain about that first.

Orchids, for the most part, have definite, but meager demand for nutrients. "More" is not always "better", and can actually be detrimental.

As to the use of Epsom Salts to flush residues out of growing media, I think someone has taken a little piece of knowledge (not understanding) and is spreading it into an unrelated area:

When preparing new LECA for use, an extended soak in an Epsom Salts solution can help extract manufacturing residues, which are sodium salts. The magnesium ions precipitate as the sodium ions go into solution - along the same lines as a water softener, but we're dumping the water in this case. When trying to remove mineral buildup from used pots, it can also help, but less so, as the minerals tend to be calcium and magnesium carbonates.

In the very brief, transient nature of pouring a solution through orchid potting media, none of that is going to happen, plus, the precipitated minerals in potting media are far less reactive.