Brinda posted this link on the coleus forum and I'm wondering if it would be safe to use the coffee grounds on staghorn ferns and to spray the fronds with "coffee tea". I've been having a scale problem with my staghorns. So far I've just cleaned them off with alcohol on a rag. If no one knows if this is safe or not, I will just have to experiment with a small portion of the fern.
Did you read that coffee article ? It's fascinating, even thought the guy who wrote it is incorrect when he says that espresso coffee has more caffeine in it. Most people assume because of the strong taste it must have more caffeine, but it doesn't. It has less caffeine than any other coffee except for decaff. I am going to get some coffee grounds and try them on the very next plant I find with mealy bug on it. I'm going to try saving tea leaves too, and see if they make a difference. I've been using horticultural oil and it works, but for things like staghorn fern, it strips off the natural coating on the leaves. Just wiping the leaves can remove that fuzzy stuff. Doesn't seem to harm the leaves, but it's a permanent change in how they look. But pouring coffee water on them shouldn't change anything, and it should also be fairly simple to place a layer of grounds in the pot, unless the fern is mounted on bark or something. Many thanks for posting that pdf. about coffee grounds.. I am definitely going to experiment with that. Not only is going to be MUCH cheaper than alcohol or oil, it's also non toxic and potentially free !!
Forgot to say, but I'd be amazed if coffee water did any harm at all to the staghorn fern. They are pretty tough plants, compared to many others. I know alcohol won't hurt them and alcohol is pretty harsh stuff. I'm pretty sure coffee water wouldn't hurt them at all. It's not nearly acidic enough to do any harm, and so long as it's not actually hot when you spray it on, I can't see how it could hurt.
I have been using coffee grounds for several years on my cycads (revoluta, circinalis) - as well as my staghorns. I haven't had any scale or mealy bugs since I've been using it. I let the grounds dry for a day or two - and then I throw them all over the target plant. I don't use any liquid as I have found the grounds to be very adequate. I apply the grounds on a regular basis, ie: every third day to one week, depending on how many grounds I have on hand. It really works very reliably!