Leaching orchids

[peeweelovesbooks]

Do any of you leach orchids?

I read on a wholesaler's webpage that they leach their orchids with epsom salts or citric acid.

Do you do this? if so, how often and at what concentration?

what are the true benefits of leaching? is it harmful to plants?

Thanks.

[Royal]

I flush with plain water every so often. This seems to be enough. If the media gets really bad salt buildup, I just repot since salty media is usually old media.

I have used Epsom salt as a supplement, but now I just use a complete fertilizer so there is no need.

[Ray]

All type of potting media will accumulate mineral salts and plant waste products over time. How you feed and water can affect the rate at which they accumulate. Frequent waterings and the use of dilute fertilizer solutions slow that down significantly, but don't forget that if you use dilute fertilizers, you're going to need to fertilize more often. (I feed at every watering, but completely flood every pot when I do.)

There are "leaching" products available on the market - mostly sold to hydroponic growers - and we have heard recommendations of Epsom Salt, citric acid, etc., but none of them are particularly effective, simply because of the nature of buildup in the media particles. (I have two articles about that: Mineral Buildup, and Mineral Buildup in Inorganic Materials.)

Concentrated Epsom Salt solutions have been touted as a good way to remove mineral deposits from flower pots, but that takes a very concentrated solution and a lot of time, so is inappropriate for application to plants themselves. Likewise, citric acid solutions have been used to remove mineral deposits from leaves, but that needs to be washed away quickly (which you cannot do in potting media), and I'd be concerned about that pH in the root zone.

Pure water is probably the best leachant available, but it will only mitigate the buildup process, not reverse it.