Lewisia cotyledon is now so hybridized and selected in cultivation that it has lost some of it's former refinement although it can make an incredible display. It turns up regularly in UK garden centres but I wonder how many survive the winter. I bought a number and despite frame protection I lost most. The reason was that they had been grown in what looks like almost pure peat with the neck (caudex) of the plant set down – so most simply rotted off. As repotting is ideally February and not in the summer trying to do a complete pot on isn't so easy. Even in February it's hard to get the old peat compost off.
So the lesson there (which hopefully I will remember) is to either buy them from a proper alpine nursery who hopefully use a gritty loam based compost and have the caudex protected with a thick layer of grit or grow your own from seed.
Lewisia tweedyi is then possibly the best of the evergreen species coming in white, yellow, peach and pink forms. Books tell you now to water in the winter and I found when growing it in the greenhouse it's best to have it plunged so the roots are perhaps in the plunge. Unplunged it tends to get too dry and then it is hard to get restarted in the spring and then it rots or it survives but doesn't flower.
I'm now trying it in the frame as I don't have space in the greenhouse plunge and so far it has gone well. At the time of writing all of the plants have come through the winter and are plumping up and all have flower buds.
I've grown most of my plants from seed and that seems to be fairly straight forward.
Lewisias – possibly create some of the boldest flowering display in the greenhouse and frames. There are many interesting species, evergreen and deciduous but I only grow a few currently.
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Lewisia rediviva is possibly the nicest deciduous species in general cultivation. Unfortunately its one I've never done well with. I've got plants, grown it from seed but although it lives for decades it never seems to get big enough to flower except one or two times.