Haworthia roots are quite different to other succulent roots. They are mostly deep rooted with fleshy large often fragile deep feeding roots. These roots are really storage roots for food Annually they reabsorb some of the older roots. Which end up hollow husks of outer skin. while growing the new roots They do have finer smaller surface roots as well.
One thing I did notice in Japan was that many of the special Truncata and mauhanii types seemed often to be overpotted in rather large and deep pots Up to 200 mm deep for a big specimen plant.
I leave plenty of room for good root development . I was told by Suichi that even though the tops of the plant might be beautiful the roots are more important that they be beautiful and strong and full as well as the tops
The next thing I learned was the soil mix, Japan uses products that are not really available here such as Pumice, Diatamite , Akadama. They also have some nicely graded sands which we find hard to get here they also use perlite which we have.
What these products have and produce is what I have been told is the most important ingredient Air in the mix. Or what we call porosity. Also many use very large Akadama balls for crocking in their larger pots. This practice is not seen here these days very much
The mix I have devised with products readily available in Australia is some of my succulent mix Pine Bark and two grades of sand plus a few other things I will talk about this later. Perlite, large coarse grade. 3mm washed river sand (no clay) chunks of coconut fiber, Coconut crush its sometimes called (a lot of air with a bit of water holding ability)This is used for hydroponic tomatoes and strawberries.
This is first treated with a liquid fertilizer so as not to drain And lastly Scoria. I have seen some mixes with a lot or mostly scoria. I feel too much of this sharp rock can cause root damage as the plants develop big strong roots wounding or cutting them making them break easily as the mix tightens up with large new roots developing. There will always be long debates on what to use or not to use but the proof is in quality of the roots you can produce over a 6 month period
Testing for porosity I filled a one liter container with my normal succulent mix then filled it with water and drained off into a measure cup 250 ml of water and found it to have about 25% porosity. I/e 25 % air in the mix
The Haworthia mix I made I did the same test in the same 1 liter container and found it to have just slightly less than 50% porocity.
The fertilizer I use is 5 to 6 month Osmocote with trace elements, About 30%. I also add GroMax a soft immediately available complete NPK. About 20% And lastly what I think is most important it the addition of about 50% to this blend is Dolomite lime a slow release lime full of trace elements for good plant health. Most good nurserymen use this on their potted trees. Below this enough for a good sized plant
Shade Haworthia in nature often grow in deep crevices under bushes or nearly submerged beneath the soil 70% shade is what is needed. For many of mine I grow them beneath the benches under other plants. They will burn easily in overly strong light going a brown colour and losing the vibrant colours they have
"The Japanese masters I have talked to all recommend potting twice a year once in Spring and again in Autumn. As they are looking for optimum health of the plant for breeding and pollinating those big flower heads full of seed can really drain a plant. They are wanting maximum flower heads good growth and seed production when breeding. My way is to put the plant on its side and squash each of the sides of the pot to loosen the plant then ease it out by the head allowing the soil to drop away from the bigger roots this protects those rather large fleshy roots which can be easily broken.
The particular company that we are working with is specializing in only growing the best from Japan and Taiwan, sometimes paying the previous owner up to Million dollars for very special ones. This company over time has perfected the variegate tissue culture which is very hard to do So next years lot will have many more variegates than we got this year.
So, we are not dealing with $2 tissue cultures here some these are really quiet expensive plants.When we approached this company we were offered exclusive rights to sell their plants in Australia if we continue buying a certain amount for the next three years. We are the sole Australian distributor for these special plants.”
With permission to share - Australis top grower and distributor: James Lucas.