|View of south terrace with Melianthus major in the middle|
|Melianthus major up close|
|Flowers of Melianthus major|
|Seed pods of Melianthus major|
Even though it is an evergreen shrub in warmer climates, it is not always evergreen here, and indeed, even if it makes it through a winter here unscathed, it looks better if it is cut to the ground each spring and allowed to grow new foliage. That is what I did on the Melianthus in the top two pictures above and you can see how nice looking it is now. This last winter was very mild here and so all the melianthus in my garden (I have several plants in various locations) made it through the winter unscathed, but I cut all of them back, except one which I left so it would develop flowers and, hopefully, seeds. You can see what the flowers look like on the third picture above, and in the fourth picture you can see the seed pods. There are a lot of those seed pods on my plant so I expect to have mass quantities of melianthus plants next year.
Others have written that the flowers on Melianthus major are not that great, and I think I agree, but they are not bad either. Anyway, the hummingbirds seem to like them.
There are two cultivars of Melianthus major on the market--'Antonow's Blue' (named after the late great gardener Steve Antonow who grew this plant in his garden) and 'Purple Haze'. Both of these cultivars have more purple in the foliage than the normal melianthus. 'Purple Haze' has more cut leaves than 'Antonow's Blue' and is perhaps a more dramatic plant, but it is not as hardy. Indeed, I have lost plants of 'Purple Haze' over the winter and others have told me they have had the same experience with it. The plants in the pictures above are the normal melianthus, not named cultivars.
Melianthus is a very long lived plant once it is established in a spot to its liking. It wants full sun and well drained soil in our climate. It is extremely drought tolerant and it is deer resistant. The plant in the top two pictures above has been there at least 15 years. Christopher lloyd wrote in his book on succession planting that he had had a colony of Melianthus major for over 50 years.
I have had gardeners who have visited my garden express confusion about when to cut back their melianthus. Like all borderline hardy plants, it should not be cut back until the spring. The old stems help protect the plant and they can also be used as anchors for old leaves or other mulch which can be put over the plant to help protect it from the cold. That being said, I never mulch my melianthus, but if I lived in a slightly colder climate, I might.
Sometimes growers offer Melianthus minor, a cousin of Melianthus major. In my opinion it is not worth growing. It just looks like a less attractive Melianthus major but without the blue hue and with smaller leaves. The same can be said of other species of melianthus to my knowledge.
Although in our climate Melianthus major is a great plant, in warmer climates I have heard that it can be invasive. I just had a garden visitor who told me that it was a big weed in New Zealand. I have heard similar tales from California.
The easiest way to create new plants of Melianthus major is to grow them from seed which is not hard. Seed may be obtained from a number of sources, most notably Silverhill Seeds. You can also take cuttings of melianthus. I have found that I was most successful doing this if I took the cuttings in late August or early September. I have just read in Christopher Lloyd's book on garden flowers that cuttings can be taken from young shoots below ground in early spring. I have never tried this, so don't know how well it works. I have tried the late August method and can tell you that it does work.