Jane Schofield has given me an idea for just the plant I need for the garden’s only sunny border, which we have struggled with for years. The problem has been that a sudden and solitary herbaceous border in the ordinary sense just doesn’t fit comfortably with our relaxed informal woodland-type beds. We have juggled ideas for ages and tried lots of plants that have never really worked. Partly the problem is that much of the border is in the rain shadow of one of our huge Leyland cypresses, in which without irrigation, nothing is willing to grow apart from Helleborus foetidus. So H. foetidus takes care of a good part of it. The other end of it is occupied by Rheum palmatum, which started as a single plant, and has grown into a clump of three huge plants (we have not the space nor the wet in which to grow Gunnera manicata here,so R. palmatum serves as a substitute). I also have a number of Euphorbia characias subsp. wulfenii for planting out this spring. I think these three plants should thrive, and I now intend to get Melianthus major to join them.
Rheum palmatum
M. major is an evergreen sun-loving sub-shrub from South Africa, and is tender, no question about it. The RHS says it may survive temperatures just below freezing “if the wood has been well ripened in summer”. However, underneath a dry mulch, freezing is rare here, and besides, I doubt whether an occasional frost does much harm in a sheltered place, as distinct from a prolonged cold spell. Anyway, I am going to risk it, and treat it as a herbaceous perennial, expecting it to die down or be cut down in the winter. It will have plenty of shelter, and in summer will receive piped water (because the whole bed needs it). It may not want to flower very enthusiastically, but I don’t mind if it doesn’t flower at all. There are three colours I would like to add to what will be an essentially green mixture of textures. Some very bright pink tulips amongst the early leaves of the Rheum, a lupin, L. ‘Thundercloud’ which has a dusky pink/mauve flower (duskier than this rather lurid picture to be sure) to accompany the Euphorbia and the Melianthus, and a clump of Fritilleria imperialis ‘Prolifera’ to beef up the H. foetidus a bit, to be followed later by the Dahlia ‘Bishop of Auckland which I spoke about yesterday. 
24.1.2012: Received three roots of M. major by mail today, together with a leaf stalk showing how the leaves and their colour are (and how robust, considering it is late January). The roots will go into individual pots tomorrow, with a mixture of the soil from the spot they will eventually occupy, some sand, and some compost, and stay, rather dry, in my (cold) greenhouse until the spring. Meanwhile, I have turned the leaf stalk into two “softwood cuttings”,without rooting hormone, and with all but a pair of leaves cut from each one, and the remaining leaves halved. I have no great expectation that this will work, but if I didn’t try, I would never know. 
Oooh, I do like to be the source of inspiration! However, there are variables of this plant – some are a much steelier blue/green than others, and some have a better leaf shape too. I think mine is pretty tough as it has survived 2 VERY cold winters here (minus 17 several nights running) under no more than a few fern leaves. The only drawback is it does have a slightly ‘foetid’ smell if you bruise the leaves, but not very unpleasant. I would definitely select your plant when it is in full leaf so you be sure of what you are getting. Or would you like me to heave you out a root? Or both?
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I’ve heard the smell described as peanut butter, but not by me. (Remember the leaves are poisonous if eaten). It’s a mediterranean plant, so it grows in winter and rests in summer. Out of gardens and irrigation, we find it growing along stream banks. Mine is waiting for March and rain, then it will take over the world again!
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Edward Reply:
January 22nd, 2012 at 11:28 am
This is interesting, thank you. When you say “waiting for March”, being in the southern hemisphere, that means the onset of autumn for you presumably, so the plant is dormant during your hot dry summer. Here in Scotland, if we did hot at all, it would be July/August, and the time the plant needs maximum protection is right now – we can get temperatures down to -15C, and frosts prolonged for weeks on end. Although the RHS and other authorities warn that Melianthus is half-hardy at best, I hope that by treating it primarily as a non-flowering herbaceous perennial, and giving it an effective dry mulch in our winter, I may get away with it. It’s well worth a try anyway, for such a splendid plant.
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