The Great Soil Debate

jasonwipfJuly 19, 2014

Updated with best answers(7-22-14)

So while there is probably no perfect answer to this since different climates and species prefer different mixes I still see such a dizzying array of advice and growers out there doing different things and wanted to get some real world experience from everyone.

I'll start with some observations and questions:

Indian Mixes: Every video or pic I've seen from india looks like they took Grandma's ashes and mixed in sand, fine dust and pebbles. Whats up with that mix? Never looks like there is a drop of moisture in there and I have to say their adeniums look a little weird compared to Adeniums anywhere else. Thin and less vibrant in color.

Thai Mixes: They seem heavy on coco chunks/chips. From 70-100% coco chips with top layer of Coir/soil/manure. Sometimes heavy on small to medium stones mixed with coco chunks. Seems to be the best draining mixes and no one can deny the Thai get great results with their adeniums.

Western Mixes: On this side of the pond I see more of an emphasis on vermiculite and perlite. While these do the job is their a difference between these light weight fillers or just using small pebbles or grit? Then, since adeniums are to be kept on the dry side, extensive use of these very light weight mediums make it easy for plants to be blown over in strong wind.

Soil Questions:

"Never dry out seedlings" When are they old enough to start completely drying out? What defines adulthood?

If drying out between watering do we water right when it drys out or is the aim to keep dry for a full 48hrs+ to trick the plant into thinking water is scares so it fattens its caudex as drought reserves?

In the case of using full coco chunks in the bottom 50-70% of a pot like many Thai mixes do, are we trying to keep the roots lightly moist with lots of air? If Air flow is good like in Thai mixes wouldn't that allow for almost daily watering in warm sunny weather instead of waiting for long periods of dry out with more compact, smaller particles mixes?
BEST ANSWER: Yes and Yes

Any clarifications, answers, info and real world experience from you guys would be great, Thank you.

This post was edited by jasonwipf on Thu, Oct 16, 14 at 2:23

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kodom087 z9a

My head exploded with info overload. LOL

I go with cheap and easy if it works. I just haven't taken the time to track down all the stuff for the gritty mix that everyone raves about but at some point I will. I like it's texture and weight. Perlite does get messy unless I put river pebbles on top.


    Bookmark   July 19, 2014 at 12:16PM
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Hey kirk,

Overload? I thought you would be the information bank for my questions here. :-P

Have you tried wicking on your adeniums? seems as if it would be a good idea to get any lower layers that are holding moisture to release and drain water and salts.

This post was edited by jasonwipf on Sat, Jul 19, 14 at 12:39

    Bookmark   July 19, 2014 at 12:31PM
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kodom087 z9a

Haven't tried that but it's a good thought. The only thing I miss about growing up in the Beaumont/Orange area was having a water well. Seems all of Houston water has salt buildup issues. LOL


    Bookmark   July 19, 2014 at 12:38PM
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Boy thats an understatement. We have lots of hard water here. I sometimes buy bottled or distilled water for my adeniums but wondering if I should feed captured rain water full time if I can.

    Bookmark   July 19, 2014 at 12:41PM
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I'm going to take a stab at answering your questions:

Soil: The bottom of most pots are the last to dry out because potting soil retains a lot of water and gravity makes that water sit there, slowly melting the roots of plants. This is the notorious "perched water".

So what needs to happen is for the potting material to get wet, not clogged.

Layering--This idea never made sense to me. How do they keep the top part from mixing up with the bottom part that has large particles?

The layer of large-sized things at the bottom of any pot will not prevent smaller-sized particles from eventually falling into those nooks and crannies between these large-sized things. Ultimately, the pot becomes uniformly clogged with water-retentive stuff (usually peat), eliminating air spaces that roots need and the result is plant death.

Imagine putting a sponge on top of a layer of pebbles. The sponge will not absorb more than it can, but when I'm done pouring water over it, those pebbles will dry out but that sponge will still be sloshing with water. For a long long time. So I don't think layering different-sized stuff will eliminate perched water, it actually raises it, putting it even closer to plant roots and speeding up plant death.

Soil Mixes: My sister uses something very close to the Thai mix and her seedlings bloom sometimes as early as the 6th month. However, she is in the Philippines, with similar weather to Thailand, year-round temperatures between 26C to 36C, humidity at a constant 80% and higher during the monsoon season). It's like living inside a giant nostril, only sunnier. The growing season is basically twelve months long.

In those conditions, coco chunks made of coconut coir (the fibres extracted from coconut husk) are perfect for keeping adeniums (or indeed many plants) moist without drowning them. They do not compact like peat, the stay "steel-woolly" longer (thus maintaining airflow in the container) and the moisture in the air keeps them from drying out too quickly and becoming hydrophobic. Water evaporation also slows down if it is very humid since there is little space in the air for water to evaporate into, even with summer noon temperatures rising to 36C. During the monsoon, adeniums in coco fibre or coco chunks just get generous showers that wash out the roots, removing whatever salts accumulate from fertilization and what-not.

I can not speak for what they use in India---its a huge subcontinent with highly variable climate. Some places will have dry heat, others will have heavy, humid heat, others will be frigid from high elevation, etc.

I use gritty mix for my adult plants. It completely eliminates the stress of guessing when to water. I just do when it occurs to me and if it rains three days straight, my adeniums and I don't care. We drain fast!

Seedlings: After months of experimentation, I learned that the gritty mix will kill seedlings 0 to 6 months old unless you water them daily in the summer. They will suffer from chronic brown-tip syndrome (I made that up) because they are always thirsty. So what I have done is return my seedlings to a more moisture-retentive substrate consisting of 1/4 potting soil and 3/4 gritty mix. If I had more bark, I probably would have added that instead. I also have seedlings in substrates that have more pumice (holds more water than grit, but less than bark) know--improvise, adapt, overcome!

Growing up Adenium: Mark Dimmit's go-to article (link below) will tell you that the first three years of an adenium's life is when it grows the most and the fastest.

Personally, I have pinched, pruned, root-trimmed and spilled adenium seedlings of all ages up to 4 years (which is the oldest plant I own and I've only had it for a full year). I just learned from kiwijoe earlier here that he has grafted seedlings as young as 6 to 9 months old. So I'm actually going to try that!

Water: There are finicky plants that will tolerate only rain water or distilled water or RO water. Adeniums dont care as long as they get lots of it in summer and just sips in the winter, if at all.

Finally, this: on a scale of 1 to 7, where 1 is weed and mesembs are level 7 in terms of difficulty, I will put adeniums at 3, maybe even 2.

I hope this helps. If I got anything wrong, someone fix me at once! Adeniums are fun plants, yo.


Here is a link that might be useful: Mark Dimmit

    Bookmark   July 19, 2014 at 9:33PM
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Great questions!
I'd like to throw one in as well.

Given that most adeniums recommended to plant ON TOP of the soil, how deep should be the pot itself?

I see many members here have quite large pots underneath with all the fat caudexes above. Is that for stability? Or does the large layer of drainable media promote root growth?

The only one I have currently sits only on a few inches of gritty soil. It's being attached to the plastic walls with some gardening ties. I'm too cautious not to overwater but then one wonders if it's enough to stimulate further growth?

Thanks, everyone, for your insights!

This post was edited by LiliyFlower on Mon, Jul 21, 14 at 22:58

    Bookmark   July 21, 2014 at 10:56PM
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Hi lily,

I'm actually in the middle of packing but I'm grateful for the chance to procrastinate!

So here. Adeniums develop fat roots under the soil--often very dramatically over a single growing season, if there is enough heat and sunlight. Most growers slowly raise their plants to expose these fat roots little by little. I think it was Marie who does this every year or so, exposing about an inch at a time.

The size of the pot is, for the most part, largely a personal preference. For instance, I have all of my adult plants in wide shallow pots because I want the roots to grow that way. Also, I have not started raising my plants either because I want them to have at least two to three seasons of undisturbed growth before I start doing it.

So the adenium is not really on top of the soil per se. They're still in in the soil, just raised a little.

Other people here have more experience than I do with exposing roots though.

This is my Rik Ni Ran, planted in about 3 inches of gritty mix.

The downside of such a shallow, porous and wide pot is that it has to be watered more often--in this case, nearly every day, especially when in bloom. To make watering more manageable, I top-dressed with pea gravel which helps keep the moisture in. It now gets water every 2 to 3 days.

I hope this helps.


    Bookmark   July 22, 2014 at 8:01PM
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Thanks for the info pagan. Ay Pinoy?

I put my first batch of seedling i just repotted In Thai mix and yes it's dryiwr than its original soil. Most are starting to have their leaves move up and vertical instead of horizontal like they are supposed to be. 2-3 out if about 30 are developing brown tip. Should I water daily then?

As far as the 70% bottom coco chunk 30% top soil layering that some Thai do I "theorize" that the intent is over about a year ( untill the next repot) the top layer will slowly wash down until it is mixed with the large chunks and over all it is still a very draining type of mix. If I had thoroughly mixed them from the get go and after about a year the large chunks were at the top and the bottom was filled with small particles, that bottom 20% would now hold too much water and rot lower roots. Also that top 30% is actually a bit gritty too, my version is 1:5 each of: top soil, coir, sand, small pebble and manure.

Think the manure on young seedlings hurt them?

    Bookmark   July 22, 2014 at 8:39PM
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Hm. Interesting. I didn't know the Thai mix had those proportions. That's still very fast draining if they use 70 percent coconut chunks. My sister uses coconut chips as well as chunks. Chips work like tree bark (made of the hard part of the coconut shell) that is used in gritty mix.

I have zero experience using manure so I can't tell you what they will do to seedlings. You use composted and not raw manure, right? If it is composted manure then it will probably work like any organic fertilizer.

So you layered your soil? I suspect that will result in uneven moisture at different levels in the pot but I'm interested in seeing how it turns out, given your heat and humidity levels. Don't forget to update.

If I didn't have to worry about winter, I would have enjoyed trying out a variety of potting mixture.


p.s. Yes Pinay

    Bookmark   July 23, 2014 at 12:03AM
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hi Pagan,
Thanks for your reply and insights. It makes sense what you said.

Love your DR!

I hope packing goes well! :)


    Bookmark   July 23, 2014 at 1:20AM
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greenclaws UKzone8a

Hi folks, an interesting thread. I have for the first season used perlite in my DR mix.... and I positively hate the stuff! I used to use vermiculite but was persuaded that it wasn't quite right for the job so swapped to perlite. I find it continually works it's way up the mix and ends up in an unsightly layer on top of the mix....just my opinion you understand! The rest of my mix is a screened mix of same size particles of equal quantities of 'reptile' bark, horticultural gravel, a very small amount of general purpose potting mix and the dreaded perlite. I have always thought that the particles need to be the same size (whatever their size) so as to prevent the smallest from working their way down to the bottom of the pot. I have never had a problem with the vermiculite holding onto too much water as suggested elsewhere so they don't ever get root, bearing in mind the conditions I can provide, next year come re-potting time I will revert back to vermiculite as it works best for me and my plants. I fully appreciate that others will argue for the virtues of using perlite as opposed to vermiculite, but I know which will get my vote next spring!

Gill UK

    Bookmark   July 23, 2014 at 3:51PM
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Ok so in the quest to answer which type of soil adeniums like I have taken 2 month old seedlings and planted my best 56 of 72 seedlings in 4 rows with the following mixes inspired by different mixes I have read about. Each of the seedlings started the first 2 months of their life from a 100% coir mix that came with Burpee seedling kits.
Four Mixes:
1. Gritty mix= soil, stone, sand, coir, chic grit equal parts.
2. Gritty mix/Coco chunks 50/50 mix
3. Coco chunks/Coir 50/50 mix
4. Coco chunk 100% mix

I'll report this winter or next spring if one row outgrows the next!

    Bookmark   September 16, 2014 at 7:15PM
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I keep and breed Adeniums in Phoenix, Arizona and have been for about 3 years. I have experimented with many soil mixes. I like to error on the side of larger grain and more drainage because I like to water my plants a lot. It helps in the cool months too as the roots breath and tolerate watering better.

For my medium to large adeniums I use mixes that include coco husks/chunks. For me mixes with coco chunks overwhelmingly outperform soil mixes without. I mix 2 parts coco chunks, 2 parts cactus soil mix, and 1 part pumice.

For small plants and seedlings I use 1 part pumice with 1 part cactus soil. The coco chunks can float so they dont work as well in smaller pots.

I have used other items like turface and large grain diatomaceous earth (Napa floor dry) in my adenium soil mixes very successfully.

My Adeniums do enjoy acidic conditions a bit. Also, for me a big factor with adenium success is the type of pot planted in. Plastic or glazed ceramic pots require lots more drainage than clay pots. I avoid these altogether and try to use only clay pots for adeniums.

    Bookmark   September 19, 2014 at 7:23PM
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Here in Florida it rains about every day during the late Spring through early Fall. Hot, humid, and wet. (It's been raining for the last two days constantly). In addition to growing Adeniums, I also grow other succulents (mostly Euphorbia's) and cacti. Over the years I've tried various combinations of soil’s, some of which others have already mentioned. However, the one that works the best for me and provides optimal root growth (with virtually no root rot) and optimal plant growth is the following:

(1) One Brick of Coconut Coir (11 pounds)
(2) One 8 quart bag of Perlite
(3) Break up the Coir in a large bin and add water. Mix until it is nice and fluffy. Mix in the entire bag of Perlite. That’s it. It’s ready to go.

My Adeniums are all potted using this mixture. I use this same mixture for starting my seedlings. Most of my plants are outside and get rained on every day. All are large size, flowering plants and are potted in 8” plastic pots. I get my pots from WalMart and they are the Colonnade Planter series of pots. You have to punch out or drill out the molded holes in the bottom. In addition, I drill another hole in the bottom/middle of the pot for extra drainage. Although they are 8” at the top, they taper to about 5 ½” at the bottom. The results speak for themselves, which you can see under a previous post: An Abundance of Blooms.

I took a look at some plants this morning and I noted that roots are coming out of the bottom on many of them. Sure signs of healthy, vigorously growing plants. The pots are saturated, but the mixture and the pots I use allow for quick drainage with no compaction. Due to the weather, I fertilize with Dyna-Gro Grow every other week. Any excess fertilizer is flushed out with the constant rain.

    Bookmark   September 20, 2014 at 12:41PM
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The majority of the growers in both Taiwan and Thailand grow there Adeniums under the roof of a greenhouse or shed row. The rooves are coated with a lime based whitewash during the hot season and when the monsoons come. It washes off the coating.
They grow them indoors as they can then manage the watering.
There growing medium is very similar with coconut coir husk or peanut shells, coarse river sand and composted manures. Perlite is added some places as it has become more readily available.

I prefer this method of having my plants under a clear roof structure during rainy times, so that I can manage the watering and it does not interrupt my fertilizing schedule.

What works for me in my climate is coconut husk chunks, Tuface and grit #2 in equal proportions. Some others additives also. Gritty Mix.

    Bookmark   September 20, 2014 at 8:27PM
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Great posts guys. I agree Tina mine seem to like the coco chunks too. There have been a few I have repotted prematurely and in each case rapid new root growth has tunneled themselves thru these coco chunks. I suspect they will win in my little test but will wait to see this spring or next summer when I do a proper repot. JJ I know exactly which walmart clay pots you are talking about, I also bought some of those 8in pots and they are great! I didn't do any drilling out but they still seem better than any glazed pots I have.

I did try 3 small sample pots of Silica balls to try a hydroponic sorta test, so far not going well as the plants can't stand up right very well and shift as the balls shrink and expand with waterings.

    Bookmark   September 28, 2014 at 5:59PM
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Well the Hydroponic Silica ball test was a bust. after a while the balls just didn't reabsorb water very well and kept shrinking much quicker than I thought. It looked rather pathetic and I wish I took some pictures so you could laugh. Surprisingly the seedlings I used in the experiment survived. In spite of extremes in water, lack of light where I had them indoors and being lopsided most of the time.

    Bookmark   October 16, 2014 at 2:13AM
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jasonwipf, What were the results of your experiment?

    Bookmark   February 15, 2015 at 11:41AM
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I found some research suggesting that adeniums should be treated more like tropical plants, rather than the conventional wisdom that we should treat them as desert plants.

Stick with what's working for you, but I mix about 50/50 bark mix for cactus with regular potting soil for mine. I have no problems with that, and it does drain fairly well. I do keep mine growing year-round though. Every branch of my first one is currently in bloom.

Copied from that research:


"The Key to Success: They Aren't Desert Plants

A fundamental change in the prevailing perception about adeniums is necessary to grow them well. The common wisdom is that they cannot tolerate a good watering. I've seen many ten-year old plants only a few inches tall stunted by chronic water stress. The essence of this article can be summarized in two crucial rules: 1) Grow adeniums as wetland tropicals, not desert plants. 2) Reject rule #1 when the plants are dormant.


While some populations do grow in extremely arid deserts, it does not necessarily follow that they need to be wedged in a rock crevice and constantly deprived of water. Many xerophytes evolved from tropical species that adapted to aridity rather than migrated as the forest retreated due to climatic change. Adeniums are apparently among these, and most of the taxa have not lost their affinity for more mesic growing conditions.

All taxa (except possibly A.socotranum) respond to generous watering during warm weather. Treat them as if they were tropicals such as hibiscus or gingers and they will respond dramatically. This is especially true of many of the hybrids which exhibit great vigor. Keep the potting mix continuously moist during the active growth season. Root-bound plants may be watered almost daily in hot weather. Adeniums are planted as hedges in the Philippines and India, where they thrive on more than 60 inches (1500mm) of rainfall a year (Alfred B. Lau, Ashish Hansoti, pers. Comm.). The taxa that lack an obligatory dormancy (A.obesum and A.swazicum) can also be watered through the winter if they are kept warm (at least 80F, 27C days, 5OF, 10C nights), but let the medium become nearly dry between irrigations.

This is sufficiently important to justify repetition; Water them as if they were coleus or tomato plants while they're growing in hot weather, but as if they were delicate, rot-prone cacti during winter. Adeniums are extremely susceptible to rot when watered too frequently during cool weather or if chronically waterlogged at any season. Use of a well-drained potting medium prevents most rotting problems.

    Bookmark   February 16, 2015 at 10:26AM
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