Scottish Rock Garden Club Forum
Cultivation => Cultivation Problems => Topic started by: Mark Griffiths on January 31, 2019, 02:55:23 PM
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A couple of years back I got a number of Lewisia cotyledon Elise plants from a local garden centre. I picked out the shades I really liked and they were glorious for a while. Now I am down to one.
I had them in frames or under a polythene mini greenhouse for the autumn, winter and early spring. But they still rotted.
Looking at them the were in a peaty compost which covered the caudex (neck). Despite carefully removing the compost around the neck and putting grit around them they still died.
I was thinking of trying again but are these plants in a peat mix a lost cause? Ashwood suggests repotting in Feb so I doubt it they would take kindly to having the peat washed off (assuming that is even possible) after flowering in summer?
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Hi Mark,
I don't know whether or not they would accept washing the peat off in summer. But being too wet - especially at the wrong time - is usually what causes them to rot. "The wrong time" isn't just during winter (when it is usual to keep them barely moist, from about October to late February) - but also when the weather is hot in summer. Counter-intuitively, watering should be reduced to a bare minimum if the weather is hot. This is because they are succulent and in the wild this helps them get through hot periods - at which time it does not rain. So they expect hot periods to also be dry periods, so too much water then will rot them. When I was at Wisley we had quite a large collection of Lewisia cotyledon. We grew them in a mix of 2 parts John Innes no. 2, 1 part perlite and 1 part composted bark. They prefer a neutral to acidic mix. Like Ashwoods, we always repotted in late February, just as they want to come back into growth. They usually tell you they are ready for this by the centre of the rosette turning a brighter, fresher green colour.
An alternative might be to grow your own from seed. They are pretty easy from seed (sown now because they are cold-germinators). You can then keep them in your own chosen compost mix from the start.
Don't know if any of this helps but good luck if you try again!
Paul
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Thanks Paul, I hear what you say about watering less during hot weather - I'm learning that things like Primual allionii go into a sort of dormant state in the summer and heavy watering causes them to rot.
I'm thinking perhaps I should give the lewisias cover after flowering as an answer.
I did think of growing them from seed - I have a number of nice L. tweedyii from seed - but oddly I didn't get any from the AGS seed exchange - I got plenty of rare stuff as I'm a donor but no Lewisia Ashwood strain. I may try a couple of plants if I see can keep them and then try for seed again next year.
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Mark
Like Paul I use a mix of 2 parts JI2 -1 part perlite but 1 part grit - I always use a 3 1/2 inch pot and then into large squares for ease of stacking
Anything up to about an inch of larger gravel round the neck
Most of mine live in a tunnel - which has a limestone chipping floor - winter they get a splash of water every couple of weeks - remove anything dead
Summer get a soak in the evening once they flop a bit
I really need to get some of the larger plants of named varieties split up for cuttings this year- but it probably won't get done again
I have two 'Pinkee' that came from DHE plants a very very long time ago - they never seem to get done
L. Tweedyii I have in all the sand in the plunge benches in one of the alpine houses - I tend to dig them out in spring and pot the best of them up and give them to one of the nurseries I know. They are a good yellow and very prolific - originally came from Mike Bramley a very long time ago
I have bought quite a bit of Lewisia seed this year - mainly 'Sunset' strain as although I have a lot of plants with good clear colours I do like the darker veined ones
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Unfortunately Lewisia Cotyledon Hybrids are sadly misunderstood. All the relevant literature appears to assume that they are succulents and therefore should be kept dry, especially in winter.
For over a decade now I have grown thousands of these amazing plants and proved this widely held belief to be simply ill-advised.
In their native habitat they grow in rock crevices at high altitude. In this environment there are significant temperature fluctuations over any 24 hour period, at any time of year. Lewisias are most adept at harvesting the resulting condensation from the rock surfaces. They always have access to moisture.
In our environment we discovered by accident some years back that we got larger, healthier Lewisias that flowered better & longer if we grew them in one of the pots with a water reservoir underneath. I then adapted my growing environment to allow me to grow hundreds, and sometimes thousands by this method. My quality and success rates have improved out of sight. i do back the water level off a little in winter, but they still have a top-up every week.
Please stop torturing these lovely plants and try a water-well type pot.
If anyone is having difficulty accessing good quality seed with a very diverse range of colours (yellows, whites, magentas, bi-colours, etc., as well as all the usual shades) and styles, please drop me an email.
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In their native habitat they grow in rock crevices at high altitude. In this environment there are significant temperature fluctuations over any 24 hour period, at any time of year. Lewisias are most adept at harvesting the resulting condensation from the rock surfaces. They always have access to moisture.
The attached picture is Lewisia cotyledon growing on Black Butte in the Kalmiopsis Wilderness, Oregon and I think illustrates exactly what Neil is saying. The temperature at the time was in the 80s f and the rocks almost too hot to touch.
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thanks both - I guess my question is that why do they then rot off when wetter during the later summer / autumn?
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I have grown from seeds lewisia species, and soon as they were big enough they were put outside on the rockery. They have had no protection fro the weather, and whilst they are smaller than those that led a cosseted life they are doing well and some flowered for the first time last year. http://www.srgc.net/forum/index.php?topic=14591.msg362200#msg362200 (http://www.srgc.net/forum/index.php?topic=14591.msg362200#msg362200) for a bit more info
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thanks both - I guess my question is that why do they then rot off when wetter during the later summer / autumn?
Mine have not rotted off, the crowns are sitting in gravel and have good air circulation.
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ok, then the problem is probably that the plants from the garden centres have compost that covers the neck.