Any Other Topics: Collapsed Dionysia
Started by: Julie Parrott
Dionysia aretioides and 'Charlsom Primrose' developed cratersGo to latest contribution by Paul Ranson, 12 January 2013, 12:44. Go to bottom of this page.
Please could some of you experts tell me why my dionysia aretioides and also 'Charlsom Primrose' have both, since Christmas, develped a crater in the top of their cushion. How do I deal with this and how do I stop it occuring in the future?
Hi Julie. Your post has just been brought to my attention. I'm just going out and will respond more fully later today but can I just say I don't think there is anything wrong from your description but will try and explain and give you some tips to overcome this condition when I return.
Julie. From your description I'd say your plants have 'flopped'. Both are vigorous and shrubby in Dionysia terms. As they grow, as well as forming new rosettes, the existing stems elongate with only the end of the rosette being green. In the tighter, cushion species such as D. curviflora this is is not as noticeable and the marcescent (previous years dead) leaves are not generally visible. In the case of these shrubbier species/hybrids, unless you have a lot of top dressing, the cushion will tend to open up and a gap will appear at the centre. This can be countered to a large extent by adding more grit top dressing around the edges and pushing it gently toward the central crown whilst taking care not to damage the stems. I can almost hear some of my fellow judges muttering about'chocking'. It is important not to confuse the practice I have described with burying the whole plant which I am not advocating. We all top dress our plants to some extent, it needs to be proportional to the plant involved. With very few exceptions Dionysias grow from a central rootstock which can reach 1cm in diameter so there is little risk of damaging adventitious roots, just ensure all stems are above the grit as you apply it, don't bury or break any. Although not directly connected to your question, do keep a watch for botrytis at the moment as conditions across much of the country are ripe for it and I am spending a lot of time dealing with it. Remove any affected rosettes promptly (I even remove individual leaves on some plants like D. viscidula) and also remove any flowers as soon as they start going over as a soggy corolla tube is a primary source. Fortunately the plants you mention are not among the more prone to this potentially disastrous condition. Good luck and please add additional posts if you have further problems.
I should have just added that your's are among the thirstier species/hybrids and although it is a careful balancing act it is important not to keep them too dry at this time as at the very least the flowers may abort. Obviously ensure the foliage is kept absolutely dry.