A rescued plant and an appeal for a better definition of the term 'fast-draining mix'

Yesterday I went to a garden center looking for a plant of lavender (Lavandula sp.) to be used as infusion for bathing purposes for my newborn son, when I chanced upon a solitary plant of Haworthia attenuata var. radula in one of its many variegated forms. Almost immediately I noticed one of its leaves being in the early stages of rot and reckoned that it will collapse within a few days, which can spread to surrounding tissues and lead to the plant's demise if nothing is done promptly. Already while being on the lookout for a good sized lavender I noticed quite a number of people taking interest in the myriad forms of succulents also being offered for sale, and basing from what I am hearing from their conversations, I am quite certain that most if not all of them are novices to the hobby. I ain't no seer, but being a member of quite a few cactus and succulents group on Facebook, I thought that there is a likelihood that pretty soon, someone will post a photo of this very same radula, asking for tips on what to do with the rotting leaf, or worse, on how to keep it alive.* Whichever the case, the plant already has one of its roots teetering on the edge of mush-dom, which is already a crying shame considering the plant's potential. And so before anyone else beats me to it, I staked my claim as its new owner, but the decision was driven more by a (heroic) desire to save it than anything else.

The discoloration on the rightmost leaf is a sure sign that rot has set in, at least on that leaf.

Photo shows the extent of rotting. Healthy tissues at the leaf bases are supposed to be white.

Here's a normally colored radula in comparison. Aging leaves should be turning brown all throughout, and not localized and eventually spreading. Which reminds me, I need to move this chap to a bigger pot now that it's beginning to outgrow its present one.

The following day (today), I removed the entire plant out of the seedling bag it was in, then gingerly removed the old media off, which is leaf litter already in the advanced stages of decomposition. After freeing the roots, I washed off the remaining particles and was rather horrified when a small earthworm crawled out from the plant's base. Don't get me wrong. I have no qualms handling earthworms at any size with my bare hands, but one is not supposed to be found crawling on a succulent plant! Photo below shows the old medium. At that stage, it is already highly acidic** and would have killed the plant in a matter of days or a few weeks before it totally turns into sludge. Needless to say, I just had to chuck this off away; I will not even consider using it for my emersed aquatic plants.

No, that is not a pile of crap.

To rectify the situation, I prepared a fast-draining mineral mix consisting of ungraded pumice and S1, or crushed aggregates. This is my default mix which constitutes the main bulk of the mixes I use, but also augmented by other rocks that I am keeping for such purposes.

Ah, that nostalgic feeling of being in a hardware yard...

Some of the rocks that I keep around for my succulent mixes. These are of course in a plastic bag; some are just scattered around and likely to be kicked around or stepped on to.  

Potting the plant is pretty straightforward. An important consideration is just to be very careful not to break off any of the roots, the wounds of which can be avenues for infection. Because the infected leaf's base is still quite turgid, I opted not to pull it off or even cut it, as doing so may result in a proverbial Pandora's box.

After potting the plant, I sprayed it from above, all the while removing particles from the medium off the leaves. I know, many of you would be appalled by this and would choose not to water a plant that already has one of its leaves showing some early rotting. Most will even recommend air-drying the plant for a few days before potting it. But my growing area receives plenty of air movement and the choice of an open and inorganic soil allows quick drying around the bases, but retains enough moisture around the roots. After this, the plant won't be watered again until the infected leaf collapses and dries up and pulled off the plant.

The fast-draining mix

As mentioned above, if the plant was bought by someone else, then it will almost be surely moved to what has been termed a 'fast-draining mix/medium', whether it was due from an advice given by someone else, or the new owner's decision. However, a fast-draining mixture is actually very vaguely defined: Styrofoam chips and chopped coconut husks are both fast-draining materials from an horticultural point of view, but are hardly useful for succulent cultivation. Its old medium of leaf litter started out as a fast-draining medium too, before it began turning into muck and impede drainage. For sure, many will advocate using inorganic materials as additives to an otherwise nutrient-rich mix, but this only solves the issue within a certain time frame. Once the organic matter starts to break down, soil chemistry swings to the direction the plant's roots will have difficulty adjusting with (i.e. progressive acidity), and if not amended in time, can result in irreversible damage to the plant involved. For the latter, the course of action is repotting, but this is not without attendant complications. I do not enjoy repotting, and am certain that none of my plants do too. Repotting runs the risk of roots breaking off, which can invite infection and overwhelm an already embattled plant. Sure, one can air dry, but this method further adds to the plant's already heightened stress levels; the longer the plant roots are exposed, the longer the plant recovers. And even if everything went smoothly, it would be just like starting over again, as if the plant is a new purchase. Growth comes to a halt until such time that the roots start growing again. Of course, one can delay the inevitable by watering the plants under a careful regimen and I will not even question the efficacy of that approach, but I think I will rather opt that risks are eliminated for my plants if these can be eliminated anyway. I am not really into playing Russian roulette with my plants. Those who have been quite familiar with my approach surely would have noticed that I tend to over-pot, and this is for two reasons: to allow better root development, and minimize, if not eliminate, the possibility that repotting will have to be undertaken again. Given the choice I'd much rather repot for reasons of moving a growing plant to a larger container than as a last ditch effort to save it.

So when we say 'fast-draining', it is imperative that we qualify the term. Too many times I have seen recommendations about using a quick-draining soil, but the concept is not often expounded well. Do we mean a mix that is purely organic, or something like an organic soil and pumice mix in varying proportions? Or are we referring to a mainly mineral, and thus inorganic, mix? Almost any substrate can be fast-draining but their properties aren't the same. There are fast-draining mixes that eventually become clogged, and there are fast-draining mixes whose structural integrity stays for an indefinite period of time. I have repeatedly advocated against the use of organics except when used in very small amounts, or in special cases like the maintenance of seedlings or mass propagation, although still advising against using it as the main bulk of the mixture. Organics always present the possibility that something will go wrong, inorganics does not. Once you see earthworms shimmying around your plants' soils, then you know that something is out of place.

And yes, I did not forget to get that lavender.



*The cactus and succulents hobby is particularly notorious in having practitioners that are driven by impulse buying, then asking people on how to maintain their new purchases. Such a practice is seldom the norm in other groups of specialized plants, such as carnivorous plants, where collectors take pains in researching about a plant's need before actually buying one.

** Many succulents prefer slightly acidic substrates, but there is a limit to the degree of acidity they can appreciate before they start to react negatively.