I am still learning about Sinningia tubiflora, the ‘hardy’ white ‘gloxinia’. It is grown for its long-tubed, sweetly scented flowers that are produced on long stems above the rather fleshy, downy leaves. It grows from rounded tubers and is on the borderline of hardiness. It has a reputation for being rather shy to bloom and this is usually put down to insufficient winter chilling or disturbance of the tubers. I first got the plant in a 9cm square pot and repotted it in two stages into a 20cm pot. I used a mix containing loam. It bloomed the first year and has done well subsequently. What has been most impressive is the growth of the tubers. Last year shoots started to appear through the drainage holes and the plastic pot was split by the expanding tubers. It was time to do something drastic.

The tubers are formed along subterranean stems and they seem to want to burrow deep. All the healthy tubers are at the bottom and at the sides of the pot. The top third of the pot has few new tubers. So I tackled it by removing all the healthy tubers at the base and sides and these have been potted in fresh compost in loam-based compost. By now I had ten 10-15cm diameter pots packed with tubers, far more than I need. And I still had the original clump of tubers. So I have taken the plunge and planted this, deeply, in a raised bed, beside a palm, agapanthus and grevillea. Only time will tell if it gets killed by the cold or spreads like a weed. Whatever happens I should have lots of flowers in the other pots. And if I don’t then I know that it doesn’t like root disturbance.

While I was in the greenhouse, under the watch of Mia who likes to lay on the shelf, making sure I do things right, I repotted the polianthes, till I ran out of compost. I mention these from time to time, including here. It is usually suggested that they are discarded after flowering. This is because the ‘bulbs’ are not true bulbs – after all this has been renamed as an agave! New shoots grow from around the old, dead bulb, attached to a basal stem. I have left mine in their original pots for too long and there are now clusters of small shoots and there is no way these will be able to bulk up into flowering sized bulbs unless I do something. Each bulb had become a cluster of at least 20 tiny bulbs. Now I could have removed them and potted them separately but I can’t keep hundreds in small pots. So I cut them into smaller clusters, potted in good loam-based compost and will grow them on and see what happens. In theory, if the growing season is long enough, they should bloom this year or next, but Ireland is not perfect country for polianthes so I will be happy for them to just get bigger this season.

I try to keep the plants warmer than 5c in winter and just moist so they are not completely dormant, but they don’t look very happy at this time of year. I may plant some in some rich compost in the polytunnel beds to see if that improves growth. They are not very attractive plants when not in bloom and I don’t think I can cope with half a bench of polianthes leaves when pelargoniums or fuchsias could be blooming in their place! It is a lot of work for the hope of those richly fragrant flowers in late summer but optimism is the best fertiliser for lots of plants.

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