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I'm still trying to grow carnivorous plants, and with reasonable success.

Recommended: Peat / sphagnum moss

Now generally, these plants grow in "wet, boggy, acidic soils" as every source will tell you. The soil needs to be low on nutrients, since the roots of those plants can't handle those nutrients and fertilizing may even burn the roots.

Peat is the general recommended medium to grow CPs on. However, live or dried sphagnum moss is hard to come by and quite expensive. And you can buy peat which is cheaper, but it isn't environmentally friendly, because it's dug up from wetlands in Belarus and such. The peat bogs here (in the Netherlands) have been destroyed years ago when peat was still used much as fuel.

Alternative, beech leaf mold?

Anyway, since I'm going to plant my plants outside in the garden, I'm going to need quite a large amount, and I'd like to try a different medium: leaf mold.

The reason I want to use leaf mold, is that it has similar properties. It retains moisture quite well and it is low on nutrients.

Now, I've bought some leaf mold from an organic grower. This is compost from beech leaves which are gathered from the area around the grower. It is a great material, but it isn't by far as acidic as the peat I have. The peat is somewhere around pH 5 to 5.5, and the leaf compost is around pH 7 neutral.

Question: Is the acidity necessary?

So the main question: is the acidity a necessity or do they just 'happen' to grow in acidic environments?

If it is necessary: - Why? What is the scientific explanation behind it? - Is there a way to make the soil more acidic without resorting to chemicals and without adding nutrients or other stuff that kills my plant? - Is there another medium that might (also) work? I read that sugar maple leaf mold may have an acidity of around 4.8, but that will probably not be available here in the Netherlands. Are there other kinds of leaves, or maybe another material altogether?

Experiment:

I'm actually trying this our right now by moving some young plants to the leaf compost environment. I must note I'm testing now with drosera binata and drosera capensis, both of which are very easy to grow. They've been in the leaf mold for a couple of days now and so far they seem to do well, although it's probably too early to really tell. Still, awaiting the experiment, I'd like to know the science behind it and be aware of alternatives.

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Question - Is the Acidity Necessary (and why)

Yes, it is necessary, but Drosera will grow in a ph anywhere between 7 and 3, so your beech leafmould should be fine. The reason they require this is because they're genetically adapted for conditions which would normally discourage most plants - soil with a low decomposition rate, such as in peat beds, (too sour and stagnant for most plants) and high water conditions, which inevitably means acidic and poor availability of nutrients, in particular, Nitrogen, Phosphorus and Calcium. The saying 'nature abhors a vacuum' applies here, and Drosera's living requirements are evidence that, no matter how inhospitable the conditions, something will exist there by means of genetic adapation (though of course, not always plants).

If temperatures are appropriate, many of the Drosera would likely do well in bog gardens, where the soil becomes waterlogged and drainage isn't great - this would slow down decomposition, gas exchanges and nutrient supplies, conditions which they appreciate.

The link below should be of interest to you, if you haven't already seen it

http://www.unc.edu/~franco/writings/drosera.html

  • If I understand correctly, the soil (high water, low nutrients, slow decomposition) is what these plants are adapted for, and the acidity is an almost inevitable byproduct of those conditions, so the plant is adapted to that too, although pH 3 to 7 is actually quite a broad range! Thank you very much for this insight, and for the article that also describes this in detail. I'll try to find similar information for other species and continue the experiment. If I've got interesting findings, I'll post updates here. – GolezTrol Aug 14 '15 at 14:27

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