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Alternative growing media for carnivorous plants.

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This section is intended to provide a home for the increasing interest and threads in relation to sustainable and peat-free cultivation of carnivorous plants, to enable members to feed in and get out the information they need and to share their experiences in one place.


· Enable carnivorous plant growers who want to use no or less peat, to do so without detriment to the plants they grow.

· Contribute to sustainable growing media stewardship and the protection of peat bogs.

Primary ambitions:

· Better information on sustainable and peat-free growing materials

· Qualify the merits of those materials, their availability, reliability and security of supply.

· Differentiate between products and sources.

· Provide information on how best to use sustainable and peat-free ingredients

From 2014 the Carnivorous Plant Society is beginning a trials programme (18ft x 14ft polytunnel, supplied through the Society’s conservation fund - £497 donation). They will be testing a variety of sustainable and peat-free ingredients on the market and comparing them, through a series of pot trials, against traditional methods of peat cultivation. This information will be openly shared.

Example mixtures include:


Peat: 2 parts Sphagnum peat : 1 part perlite


Peat-free mix: 2 parts coir : 1 part perlite

‘Sustainable’ mix: 1 part coir : 1 part river peat : 1 part perlite

Reduced peat: 1 part coir : 1 part extracted peat : 1 part perlite

They will also look at the quality of some ingredients, for instance between ‘organic’ coir and ‘washed’ coir.

The Society will also be engaging with the market place re primary ambitions mentioned above.

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Marvelous addition to the forumn Andy.

I desparately need an alternative to peat, but nothing I have tried so far even come near an equivalent result, (only based on one off pot trials) bearing in mind that most of my growing is outdoors, any small retardation in growth bought about by the growing medium, is somewhat magnified by the cooler conditions that my plants experience, so I will watch this section with baited breath. I have tried mixes with perlite, rockwool and pine bark, clay balls peat and perlite and various other mixes, with some, but little success.

Is the general consensus that the acidity moisture retention of the substrate more important than an open texture? or am I over simplifying?

Very best of luck.



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Have you tried coir at all Steve? I don't mean on its own but as part of a mix such as 2 parts coir and 1 part perlite (or grit)? Although I've never used it, I have read that coir does need something to open it out and help it drain better, peat does too but I think the coir even more so. I'm not sure if it will need opening up more or if it just needs the same to be added as a must.

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This should be a good topic.

Where are the trials to take place Andy? I only ask because there is a difference between growing down south and up north.

Also there's a difference in the quality of some clones of various species when grown further south due to a warmer/longer growing period.

I have used moorland gold for the past couple of years but i'm coming to realise that there is something missing that the plants need.

It can be too dense or wet in winter.

I have just started a few trials of my own (with peat) waiting for the howls of disapproval.

But as you stated in the opening passage

to do so without detriment to the plants they grow.

This peat was recycled if you like,the original buyer bought too much,so i took it of his hands.

These trials are only my personal ones,not very scientific but its the results that count.I have left some plants in moorland gold,repotted some in peat/perlite and repotted some in mid season just to see what happens to those against the other two.


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still never understand the sustainable quote made when it comes to coir just need to look at vast area's of india,sri lanka and thailand(not seen the damage anywhere else but seen it there)that have been destroyed and polluted to provide growing area's for coconuts. the waters ways and mangroves swamps destroyed to manafacture the coir

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Hi ada

Might be a little confusion. I asked Andy if he would be kind enough to set this section up, and I wrote the opening text to kick start things.

The trials are happening in Somerset, Wellington and I'll be leading the work for the Carnivorous Plant Society.

As you say there will be differences across the country, and I would hope when we are in the swing of things other growers around the country will look to replicate what we are doing. Not everything of course, but one or two mixes and one or more species. Perhaps even additional ingredients too!

No howls of disapproval re using peat, though of course I would hope from a personal point of view that over time that we can become less dependent on extracted peat from what we learn and share. Certainly quite a bit of hope in regards to Sarracenia which are usually by far the biggest users of the stuff, as my experience is that they seem to do quite nicely without peat. I've been growing all mine, apart from a few other trial mixes, in just organic coir (Fertile Fibre) and perlite for 5-6 years.

I would class the CPS trials as semi-professional, as of course we do not have the full resources available to us in comparison to scientific institutes. What we do have is dedication and at least I'm in a good way a soil scientist in my non-cp profession.

What you do will be of value, what's key is to record at the least the ingredients/source(s), mix/ratio, species trialed and of course growing condition (e.g. lots of cloud and rain in your case, though hopefully not when I come up north on holiday this summer!).


Tim Bailey

Chairman and Publications Editor

The Carnivorous Plant Society

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Hi pulsar

You comment is a fair one and why sources of materials are key here. I would hope these issues would also be explored to give the overall picture. Perhaps a topic for a thread of its own?

Coir of course is a by-product of coconut production and if not used would still be produced and produce ever increasing coir mountains as it has for many years. Most coir (washed coir) is still being mined from historic heaps, and I for one need to learn more of what happens to the water that is used to wash out the salts.

For now I just use organic coir certified by the Soil Association as my kite mark.

The word sustainability on its own is an interesting term, and is better defined 'as sustainably as possible' or 'sustain something for as many future generations as possible before it eventually runs out'.


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Hi Steve

Basic requirements for cp's are water, pH, oxygen (roots) and something to support the plant. My best VFT grows in bubbled water (supported in a mix of gravel and perlite in a netted pot) and out performs my conventionally growing ones.

Open texture is very important to give the roots plenty of oxygen, and to stop anaerobic condition developing and an overdose of carbon dioxide that comes with it. A mix with an open texture will give the best results, though as you state it must still be able to hold and supply the water needed by the plant. So about balance really.


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Tim, i have used coir,a long time ago.It was crap!

Moorland gold is o.k for mature plants, they grow o.k and look o.k but compare them to sarras grown in peat/perlite and i think there is no comparison.

Also seedlings germinate in it o.k and grow,very slowly.There is something they need missing!

I have the same batch of seedlings in peat/perlite and moorland gold,the ones in peat are double the others size.

I'm not against giving up using peat,but the stuff in its place needs to be at least as good.

There is a post on the forum today about someone who may give up growing cp's(not what we want to hear)because they can't get a suitable growing media locally.

I compare my plants in the peat i got this year,to when i first started growing cp's,the peat is of great quality and the plants look good,like they used to.

Why would i want to grow plants that don't look as good as they did years ago because we can't get the right stuff to grow them in?

IS europe banning the sale of peat? or just England?

Could a few people get together and import some good stuff?maybe the CPS if the carnivorous plants need it to survive and thrive.

just me letting off a bit of steam

keep the news and views coming.


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Hi ada

Different experiences re the coir I use (source is very vital here), I personally do not see the difference and have a totally difference experience to you (based predominantly on my Sarracenia). The question then is why has it been crap for you and good for me. There are lots of potential reasons.

To me this section is not about Defra policy making peat very hard to get hold of in the future in England and trying to find a way around it. It's also not about being anti-peat. Simply a place to focus and help increase our knowledge re sustainable and peat-free cultivation.

If I can't grow a species without peat I simply won't grow it, with the exception for endangered species conservation where it is needed, which of course is a personal choice. Likewise yours is a personal choice based on your own experiences, etc., and entitled to it.

Your experiences with alternative ingredients may not be good to date, but it's very important they are expressed and to learn why.

As for your question Defra are not banning the use of peat as such, though their Policy will make it incredibly hard to get hold of by the general grower. There are no plans to do similar in the rest of Europe, at least as far as I know.

Glad to have you along for the debate.


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Hello Mobile,

Yes indeed Coir does contain humic acids in the form of Tannins.

Tannins gives the very brown tinge in the water when passed through Coir medium, the first time.

I personally flush a pot of coir with boiling water 10 times and the water is clear when I do this.

I'd love a more numerical experimental approach to Coir by testing the soil properties instead of trialing by carnivorous plants because

this will eliminate "lurker" variables in your experiment that also effect the growth of the plant (which you are using to evaluate results) e.g such as: sun amount, pot type, climate/location, etc etc. A good design of experiment (DOE) will be the difference between results which are solid and conclusive or can be interpreted in different ways by other people.

One numerical example (not completely DOE perfect):

1) Test TDS (total dissolved solids) of the boiling water flush from a pot of coir and graph it from 0 to 10 flush (or more).

2) Test pH cause I've heard coir isn't acidic enough but we need evidence.

I've also heard that salt content is related to the location of the Coir Harvest e.g. Sri Lankian product is harvested more inland and hence is not exposed to sea salt where as Indian product is, but don't know if it's a valid claim.

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I like DennyP's approach, as I have had mixed results using coir, others claim good results, whilst some claim bad, so there are clearly some variables here. The tolerance to coir also seems to be species dependent for me.

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The tests on coir will include pH and EC as we will need to differentiate between washed and unwashed coir. Can include TDS.

FYI the Fertile Fibre Organic Coir has a pH of 6.4 and a EC of 240 microS/cm (last analysis they sent me)

Difficult to go beyond this re very lack of money available, but open to further suggestions.

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Will this trial include more specialist plants, like Drosera (tuberous, pygmy, S.American, etc), Utricularia (terrestrial & epiphytic), etc? And not just Sarracenia? It would be useful to include as wide a range of CPs as possible.

Personally I will concentrate on growing Pinguicula (both temperate and tropical species & hybrids) from now on, as I'm sure it's possible to grow the vast majority of these peat-free already (using Coir, Multi-Purpose Compost / John Innes, Clay granules [terramol / Seramis / cat litter], Pumice, Perlite, Vermiculite, etc, and various mixes thereof).

Incidentally, I expect a good alternative to peat would be a 50/50 mix of Fertile Fibre (the Organic version) and chopped/milled Sphagnum moss. Of course we'd have to start cultivating Sphagnum on an agricultural scale to make it worthwhile - maybe several hectares (split over multiple sites) under polytunnel, say in the west of UK / Europe to take advantage of the milder + wetter climate for faster lush growth. Maybe setup a co-operative of CP nurseries / enthusiasts to run the "Sphagnum farms"! Just throwing an idea out there... :-)

EDIT: also, I'm sure it must be possible to grow many CPs without peat anyway, at lots of them grow in non-peat-based habitats in-situ: for example, many Australian Drosera grow in laterite or clay-based soils, quartz sand or Eucalyptus-based leaf litter, if I recall correctly from the Allen Lowrie books, so no peat in sight! So it must be possible to provide something closer to their natural soils anyway.

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Hi Adam

Agree with all your comments. :yes:

We will have to start off with Sarracenia, VFT and some of most commonly grown Drosera and to build from there as we will have limited resources. Over time we will add a larger number of more specialised genera/species. We will also need plant donations. At the moment I'll be using divisions from my collection, Ian Salter's and a few from Dennis Balsden.

One of the mixes will be coir and 'sustainable' Sphagnum as I share a similar view, in particular by helping maintain a suitable pH for one.

You can add VFTs, which in places grow in quartzite sand with low organic matter. When in N and S Carolina last summer I took care to look closely at the soil to around 10 cm, and took some pictures. Nepenthes are also commonly cultivated in a well washed coir-based medium.

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Hi Adam,

I too grow temperate pings in moorland gold.I find these behave like sarras,adult plants grow well,seeds germinate easily and grow well the first year but then slow down unless you feed them.Its good because you don't get the moss growth that will crowd them out.

As you say though pings can be grown in many types of media equally well.

My point is not many people will stand up and say what they think in favour of peat because of the anti peat brigade getting on their backs.

my tests with peat again began because of slow growth rates and division rates when compared to other growers across europe.

This could be due to their better climate or conditions,i think its to do with the slow decline of the quality of peat we have been getting over the last few years.Its mostly black now instead of the nice light brown colour it used to be when i started growing.

So when i got the chance of the peat i have now,i took it.

My trials aren't massive,i simply don't have the room,they are limited to a few pots here and there of various seedlings and plants.

I have left the old pitchers on my seedlings from last year so i can compare growth rates better against each other.

I will try to get some pictures and explain better when the rain stops.

all seedlings are from the same batch of seed sown at the same time without any extra feeding what so ever and grown in the same greenhouse.

any tips on getting better trials are welcome.

pictures to follow


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I think the best way to face critics is to be proactive on the subject. If trials the CPS and others do show that for some species that peat is still essential then we can support that position from a place of strength, particularly for species conservation. It's impossible to defend something without evidence to the contrary. As can be seen from a few posts already experience with peat-free ingredients is mixed and evidence is very subjective.

The CPS trials will be comparative and will help improve our evidence base either way on the subject. As a Society (with my Chairman's hat on) we will then be in a better position to inform both sides of the debate, including the continued use of peat until such a time as safe, productive and cost effective alternatives become available (if ever).

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