Friday, December 14, 2012

A Coffee Break for Nepenthes

Fertilizing Nepenthes is a pretty hot topic. When I first started growing them everything I read said to never fertilize. This made sense at the time because the whole reason they are carnivorous plants is because they evolved to take in nutrients through their leaves instead of their roots. Nepenthes naturally grow in very nutrient poor soils, just like all other carnivorous plants. Watering them has probably cost me a lot over time as I use distilled water on mine. Our tap water back in NY was pretty hard, so it would kill them eventually trying to water with that. I used to collect rain water, but I now only use it on the Neps that go outside seasonally. I found it brought too much fungus and mold if I used it in a closed environment. There's also the option of using Reverse Osmosis water, but I won't have extra money for even a small one anytime soon.

Now nutrient poor doesn't mean nutrient devoid, so some brave people were spraying low doses of fertilizer onto the leaves or into the soil. It turned out well for those that found the right way to do it. Too much and the roots could burn and it could kill the plant or the plant would just stop pitchering and not do well. Too little and it was a waste of time. I passed on trying too find the right way to do it back then as the last thing I wanted to do was kill a healthy growing plant, just to try and make it grow better. However, within the last few years coffee has come up as another way to fertilize them.

Coffee works. I decided to try it after I let those brave, experimental people before me risk their plants first. I didn't have any to experiment on at the time, so waited to see how it worked for others for a while before making any decisions.

Coffee works for Nepenthes for a few reasons:

1. Coffee is acidic, most Nepenthes like their soil on the acidic side. If you use media that doesn't break down quickly, re-acidifying the soil at some point between re-pots isn't a bad idea.
2. There isn't a lot of minerals in coffee, but there is nitrogen and other trace nutrients which Nepenthes can use. Not so much that it can damage the roots, as long as you don't brew the coffee with mineral laden water, that is.

So I've been brewing a pot of coffee at regular strength with distilled water, letting it cool down and then watering some of my Nepenthes with it about once every six months or longer. This isn't exactly the most scientific experiment, as they are different species and my only control are ones I haven't tried fertilizing yet for one reason or another.

Below is newest leaf produced after a coffee treatment on my N. robcantleyi. All the old pitchers had dried up when I moved it to a lower humidity environment indoors for the winter. Now maybe this burst in growth is a coincidence, but the humidity levels in my apartment had gotten worse, not better. This looks like more than it's adjusting to new conditions to me. I've never seen a Nepenthes put out a bigger leaf right away, usually it throws out a smaller one or one that's slightly deformed before going back to growing normally when it has to adjust to a new environment.

Newest leaf after coffee treatment growing towards the bottom of the picture

Below are the newest leaves on N. ventricosa. I gave this one a coffee treatment back on the same day as the robcantleyi. The leaf growing straight to the bottom of the picture and the new one that hasn't unfurled yet are post-coffee leaves. N. ventricosa is a faster grower here than robcantleyi anyway, but this one had to endure a move to lower humidity than it likes too. Not quite as big a jump up in leaf size as robcantleyi, but still significant.

Post coffee leaf #1 growing straight down the picture, #2 not unfurled yet top right

I'll wait a few months before feeding them or fertilizing again, because too much could still cause the plant to stop making pitchers. A Nepenthes that wants to catch insects makes pitchers, an over-fertilized one won't. Same thing applies if you stuff the pitchers full of insects, it''ll temporarily stop making more. It seems pretty simple a concept when you think about why a plant would grow the way it does. Everything in nature happens for a reason.

Small Disclaimer: Coffee isn't a substitute for normal fertilization. I wouldn't recommend it for any other plants as it does not have all the nutrients the vast majority of other plants need.


  1. Very interesting read! Thanks. In a sense there is some equal notes to succulents, but we use 1/4 strength balanced feed.

    1. That's true, I fertilize my succulents very carefully as well, another type of plant that doesn't need much.

  2. This is really interesting Melody. I wonder if tea has similar properties? Like watering, sometimes it's easy to over-fertilise as well. I've got to be careful to not over-fertilise my plants because that would be really sad if they died from being overfed, lol.

    1. I have heard of people using tea on houseplants, but I don't know if it is missing trace nutrients that most plants need or not, I have no clue as to the nitrogen content either. I don't think you really have to be as concerned with over-fertilizing any non-carnivorous plants as with the carnivores though. They are much more nutrient sensitive as they cannot pull nutrients in through their roots due to their adaptations leaving them more vulnerable at the root system to a build up than most all other types of plants. They can't use the rest of the N-P-K ratio as well as the minerals other plants absolutely need to survive.