The other day I went to the Botanic Gardens where they had a large and shallow container topped up with sphagnum moss in one of the open glasshouses. Mostly it was home to bromeliads (Cryptanthus) but there was one S purpurea with tall, lush, delicate green leaves.

I came home, all gleeful. I pounced on the S purpurea and huffled it into the sun room, where the daytime temps have been a mild-ish 25C. New leaves are now starting to show above the general mound.

So - it's warmth. The light in the glasshouse was filtered through the whitewash.

Done. :-)))