Coffee for Fertilizer?

[Kevinator]

After meeting with a professor at UC Irvine I have now officially jumped onto the carnivorous plant train and I can't get off. When doing research on growing Nepenthes pitcher plants, I read multiple reports that coffee worked miracles for these plants, whether for the terrestrial or epiphytic species (and from what I heard, many of the highland species seem to require similar conditions to Masdevallias). Since I'm too lazy to order MSU fertilizer online, I was thinking if I could use RO water coffee with my orchids. Any of you guys have experience with this?

[naoki]

Have you seen any side-by-side comparison? I see those anecdotal discussion, but I haven't seen any convincing evidence that coffee works as fertilizer. There are some evidences that COMPOSTED coffee grounds can help plants. But I guess any composted organic matters have nutritional values to plants.

I would rather use regular fertilizer to Nepenthes (at low concentration).

Also, caffeine has shown to have phytotoxicity. The roots growth is generally suppressed. I have killed lots of orchids by caffeine in an attempt to eliminate bush snails. It was a big mistake to follow the scientific paper which claimed that it is effective against bush snails and they didn't see phytotoxicicity. Brewed coffee may not achieve this high concentration (1-2%), but you should be careful.

[estación seca]

I would wonder whether the effect is pH. Coffee is often quite acid. Most CP like an acid environment, and people accustomed to using alkaline tap water for them might notice a difference with acidic coffee.

Raising relative humidity is far more important for Nepenthes than coffee could be, even if it does what it's supposed to do.

Coffee grounds applied as mulch have been found to kill a nasty scale insect that itself kills Cycas species.

[Leafmite]

I have no experience using coffee with orchids or my tiny CP collection but after making coffee, I dump the grounds in the pots of my other plants. It seems (no proof to offer) to help deter scale. I have not seen any harm to the houseplants.

Good luck with your new hobby!

[PaphMadMan]

Coffee is often used as for composting or direct fertilizing by organic home-growers but that is the used grounds, not the brewed coffee. The spent grounds are not so acidic, 6.5 or so. Uncomposted used grounds act as a slow release fertilizer, about 2.5-0.1-0.5, with magnesium and some micros. That might be good to put a little in the potting mix, but I wonder if brewed coffee could have nutrient levels that might be high for carnivores. Still, I can see why it might make sense for plants from a tannic acidic environment. If I was going to try it I would cold-brew, test pH, and proceed with caution on a few easily replaced plants first.

[kg5]

Will just stick to drinking coffee when watering!