Begonias in the garden – 6

They’re a funny group of plants, Begonias. In the UK, for most people what comes to mind when you mention Begonias is the bedding plant Begonia semperflorens and all the other brassy and brash bedding types, followed by the houseplants, typified by the rex tribe and their propensity for dying in short order.

I already knew there was more of a story to tell when I joined the American Begonia Society in August but reading through back issues of their bi-monthly bulletin has opened my eyes to what a huge, diverse, fascinating and in very many cases, threatened, genus it is. The Begonias with which most UK gardeners are familiar are a thin and unrepresentative veneer over a vast and much more interesting tribe of plants.

Things are getting serious when you go down the road of joining a specialist society for a plant group and I have to admit it was a bit of a leap in the dark when I did so. I have been working my way backwards through their publication, the Begonian, published six times a year since way before I was born. That alone is worth the 20 dollar membership several times over. There is a huge amount of information available on their website, even without a membership.

The genus is tropical and subtropical for the greater part, with very many species highly adapted to particular niches in rainforests and similar environments, almost all of which are very much under threat from human activity. I am interested in such plants, but not interested in growing them. The ones I like are those I can grow in my garden, either planted permanently in the soil, planted out or plunged just for the summer season, or just stood outside in a suitable place in pots while the weather permits.

We paid a visit to Tremenheere Sculpture Garden for their September plant fair and went for a walk round the garden while we were there. At the lowest point of the garden a stream runs in a wide and boggy area and there are some sizeable drifts of Begonias growing there. They were unlabelled but I have just discovered that their website includes a map and plant list; confirming that they were drifts of Begonia aff. panchthareasis and Begonia omeiana. I bought “Begonia aff. panchtharensis” a couple of years back and it seems that it’s actually Begonia pedatifida ‘Apalala’. Begonia omeiana is correctly B. emeiensis. I have both in the garden but Tremenheere was an eye opener onto the conditions they really want. Constantly damp, even boggy ground, and plenty of space for them to spread in.

B. pedatifida ‘Apalala’ is a robust plant with large deeply lobed leaves, attractive enough to be worth growing even without seeing much of the flowers which remain below the canopy of leaves. However, it really wants more moisture than my garden provides, meaning I had to water it frequently or it wilted alarmingly, and it will need to be kept in check if it is to stay in the space I’m prepared to give it. When all is said and done, I have other varieties which I think are better.

Begonia emeiensis doesn’t so far seem to be as strong a grower as B. pedatifida, doesn’t seem to need quite such wet conditions, flowers more freely and over a much longer period and is open enough to at least get glimpses of the flowers. I could say that its foliage is less striking, but it’s still pretty good. It is also easy to propagate because it produces a swollen lump at the point where the petiole joins the leaf blade which when the leaf collapses outwards, grows into a new plant at the edge of the parent plant’s canopy. I potted one of these bulbils in mid August and put it in my propagator where it has made good root and leaf growth.

Top of my list as an alternative to B. pedatifida for foliage effect would be Begonia koelzii. Like ‘Apalala’, this is a Nick Macer (Pan Global Plants) collection, from Manipur in India, It has similar deeply lobed leaves to pedatifida but they appear more sharply defined. The petioles are attractively spotted red, though largely hidden beneath the leaves. I have my plant growing under a large bamboo, it is clearly nowhere near as moisture demanding as pedatifida. It has produced flower buds on stems rising vertically from the ground but I am not confident that any of the flowers will open this late in the year. If they do they will be pink. Like B. emeiensis it produces bulbils at the top of the petiole which start leafing out while still attached, at least in summer and early autumn. I think that from November they would likely stay dormant until spring. I have not had this outdoors over winter yet, but now that I have bulbils that I can keep under cover, the parent plant will stay out this year, with a covering of leaves for frost protection. I have seen a pot-grown flowering plant of this species, the flowers are similar to B. emeiensis.

B. U614 was a plant that this time last year I split in two. One half stayed in the ground through the winter, protected with a covering of dry leaves. The other half went into a ten litre pot and was overwintered in a frost free glasshouse. I left the potted plant in its pot but plunged it in the ground close to the outdoor half back in the spring. The plant in the pot made more growth, flowered earlier and has seed pods which should give me ripe seed. The plant in the ground started into growth much earlier than the potted plant, in January, long before the risk of frost had passed. I took the leaf covering off to let light and air to the new leaves but could almost see them shivering in the cold January air. I kept a bag of dry leaves and put them back over the plant every time frost threatened but the plant didn’t really start to properly grow until at least May. Slugs did a small amount of damage but lack of warmth seemed to me to be what was holding it back. Later in the year it produced a good flower display, has seed pods that may yet ripen and has markedly better foliage colour than the pot plant which is clearly low on nutrients.

B. U614 has flowers above the foliage, not spectacular but reasonably freely produced over about two months. The foliage is finely divided and silvery, with reddish tints on the underside. It seems to be one of the hardiest species, surviving with me even when left in the ground without protection.

The American Begonia Society is responsible for the taxonomy of Begonias worldwide and started using U numbers to identify species and cultivars whose identity was unknown in 1981. U614 was collected by Michael Wickendenof Cally Gardens and initially distributed as B. sikkimensis, a name subsequently recognized as wrong.

Begonia sutherlandii has come through the last two winters as an outdoor plant with flying colours, something it hasn’t done in the past. It’s another bulbil producer and is starting to spread itself around; it perhaps has the potential to become something of a weed but is not at that point yet. From around mid September it flowered more than it ever has before, the only upkeep being to water those in the driest of the several locations where it is growing.

Begonia grandis is a somewhat variable species from China and Japan with two subspecies, evansiana and grandis, and a number of varieties and selections. I have long had a white flowered and a pink flowered form without having a clue whether they are recognized clones or not. In the last couple of years I have tried out a number of other variants, only one of which I regard as a useful and significant addition.
B. grandis ‘Nanjiang Silver’ hasn’t established itself in the garden, it seems to have less vigour than the other forms, or maybe I have just not put it in the right place. It does have rather lovely pale pink flowers; though the silver refers to markings on its leaves which were nothing special in the plants I had.
B. grandis ‘Sapporo’ is a form I bought from Farmyard Nurseries, pink flowered, red backs to the leaves, very similar but not the same as the pink I already had.
B. grandis ‘Herons Pirouette’ came from Growild Nursery and is pink flowered with all green leaves. The flowers are carried on somewhat lax stems but it is not very different and in no way an improvement on my original pink.
B. grandis ssp sinensis ‘Red Undies’ BWJ8011 was a selection Bleddyn Wynn-Jones (of Crûg Farm Plants) made from a Chinese collection and is the one I rate highly as a distinctive and meritorious addition. It has smaller leaves than the others, red below and red flushed above and on the stems. The mid pink flowers are by far the most prolific of any of the forms I have.

My original white form is perhaps the most robust of them all; it may be what people are selling as B. grandis supsp. evansiana ‘Alba’, I cannot be sure. It is reliably hardy, free flowering and undemanding. The flowers are pure white and really light up a shady area in late summer and autumn. My pink form has mid pink flowers in reasonable abundance and is only a little less robust than the white. Both have a red reverse to the leaves, both are superb when backlit by a low sun, both get yellow tints as they fade in November, again a welcome splash of colour in a shady garden.

All the grandis forms produce bulbils at the leaf axils at the end of the season and these detach and drop into the leaf litter when the plants die down for winter. They readily produce new plants if collected and “sown”, the only requirement being that they don’t dry out or get much below freezing over the winter; essentially mimicking the conditions under their leaf cover. I plant them in pots of compost like tiny bulbs, with the tips level with the soil surface, put them under the greenhouse bench and keep them moist.

Begonia ‘Torsa’ is effectively a giant version of B. grandis and is really something of a monster. It has huge leaves and thick stems which take it up to 75cm or more. The flowers are not disproportionately large but still make a fair show. Like B. grandis it produces bulbils, the size of overgrown peas, from which it is easy to increase its numbers. I can’t bear to dump the bulbils and am now getting several hundred every year from my fast growing stock of plants.

Also like B. grandis, a week into November, the chlorophyll in those enormous leaves is breaking down and they are beginning to turn yellow. I’m not expecting a firework display but while it lasts, I am savouring the tracery of red veins against yellow as the low autumn sun backlights the leaves.