Chlorotic Diplosoma

[JCMad]

Hello All. This is my first real post on this forum, so I will thank you all in advance for the help. I’m looking forward to learning from your collective wisdom! I am having an issue with a seed pot of Diplosoma retroversum. The seeds came from Mesa Garden and were sown in my standard mix of pumice, horticultural sand and “PRO-MIX HP Mycorrhizae” (peat based, but high porosity). Seeds were sown in March of this year and germination was excellent with subsequent rapid growth. Most of what I grow is maintained under LED lights (Spider Farmer). I started, this summer, making some adjustments in my irrigation water (which comes from a well) using Elton Roberts & Malcolm Burleigh’s recommendations for low pH (5.5 to 6.5pH) and ammonium nitrogen additions (Cactus & Succulent Journal, Vol. 82, No. 6, 2010). These adjustments to my irrigation water have produced generally positive results with the exceptions of Glottiphyllum nelii & Gibbaeum velutinum…it seemed to enhance their proclivities for becoming “morbidly obese”, unfortunately, and I have learned that I need to grow these plants pretty “hard”. As you can see from the attached photo, the tips of the leaves have become highly chlorotic, and in some instances, necrotic. There are, however, a few normal “green” looking leaves. By all indications, this would seem to be an issue with a non-mobile plant nutrient, perhaps a micronutrient, and I am wondering if there is something that I am doing culturally that is not satisfying the needs of this species. Has anyone seen anything like this? Any ideas? This is a new species for me - I haven’t grown it in the past - so my experience is limited. All other neighboring plants…Mitrophyllums, Lithops, Conophytums, Tanquanas, Rhinephyllums, Namibia, etc. are doing fine, though Mitrophyllum grande seems a bit chlorotic.

[Davey246]

If you search the website there is a thread from a few years back of several posts long about D. r. . Concensus was/is that it is a challenge to grow after it has gone dormant for its first time after germination and is naturally short-lived.

So far as nutrients go, there is a pool of wisdom that many SA geophytes require little to no nitrogen and some growers avoid it altogether. That said, if D. r. is the only species showing problems, it might just reflect the nature of the plant in cultivation, if not in habitat.

[iann]

Overwatered? Although that wouldn't be easy to do! Scorched?

[Aiko]

I would think scorched too. Where in the US do you live?
This would never be able where I live between October and March. We have had clear grey skies for quite a while now...

[Astro]

Did you keep them going over the summer months? If so, they may not have been overly happy with the higher summer temperatures. My own plant dies back in Spring and does a great job mimicking a dried out husk for 6 months out of the year. I thought it was gone for sure this year, but it just popped back up with two heads instead of one.

I have mine in 60% Turface (moler clay), 20% coarse sand and the rest sandy loam (i.e. local garden soil). I keep it bone dry between end April-October but out of the sun. During the Winter I keep it outside here in Northern CA in full morning sun (shaded in afternoon, I imagine they could overheat), but sheltered from the rain. It can be quite thirsty when in active growth.

[JCMad]

Hi all! Thanks for your input. Sorting through your questions about the growing conditions, these seeds were sowed in March of this year and grew vigorously through the summer. I am in Northern California, but - as of now - do not have a greenhouse, so these seedlings were raised in a south facing garage with a large roll up door (facing south) that allows some natural light, but the bulk of the light comes from LED grow lights. Temperatures are essentially ambient, and are fairly similar to those in much of South Africa. I should mention that I live in an area that is littered with Cannabis grow farms and with that comes retail shops that offer an amazing myriad of growing lights, fertilizers, supplements, etc.! I think that “scorching” can be ruled out. The only issue I have had with LED lighting is with young cacti seedlings (Copiapoa, Matucana and Tephrocactus in particular) and Conophytum seedlings that tend to “brown” and get stunted until they are moved to a lower light situation (some recover, some do not…I’m still learning). I also have a hard time over-watering plants…it can be very dry here, even in the winter, though we are experiencing some very foggy days right now. I have started to apply small doses of a micronutrient fertilizer (thanks Cannabis guys) to this seed pot and I think(?) I am seeing some improvement. Also, I have found that this species is found around Piketberg in South Africa which is pretty rich in limestone (there is a limestone mine there, I believe) and I think my amendments to my irrigation water may have pushed the pH too low for this species. I’m always looking for more wisdom, but I will report back if I figure things out. Thanks to you all!

[Davey246]

Diplosoma is a winter-grower so its season is upside down with you. It may just be going dormant, albeit at the wrong time of year. It should have been sown late summer or into early autumn to get the correct synchronisation.