Variegated foliage plants
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I don’t really know why, but variegated foliage is often viewed as something second class. Gardeners are frequently quick to dismiss variegation, but I think that most of us have a secret soft spot for it because even those who profess to loathe multicoloured leaves often have a few variegated treasures they dote upon.
Well, I’ll admit right now that I quite like variegated plants. Despite some of them being a bit artificial looking or vulgar, many are strikingly beautiful and there’s nothing like white-splashed foliage for brightening a dull corner. It’s really not that there’s anything inherently bad about variegation, which would be a silly thing to think about any plant’s attributes, it’s just a matter of how you use it.
Utilising variegated foliage
By their very nature variegated plants are different from the norm. For that reason many of them are suitable for planting out where they’re highly visible, as specimen plants. That’s especially true of the variegated conifers, which, in order to keep the variegation and maintain healthy foliage, often need to be out in the open with plenty of light.
Combine bold variegation with large glossy leave and the ability to grow well in a pot and you have a superb container plant. Many of the large-leafed New Zealand natives, such as the variegated karaka cultivars (Corynocarpus laevigatus cvs.) and the variegated puka (Meryta sinclairii ‘Moonglow’) make ideal potted specimens, either outdoors or in a bright unheated room.
As mentioned earlier, the use of light-coloured foliage is a good way to relieve the darkness of shady corners. Boldly patterned variegated leaves are even better for this job and can even substitute for flowers, which are often hard to come by for deep shade. Just be careful to use plants that retain their variegation in shade. You shouldn’t have to many problems with variegated perennials like hostas or shade-loving shrubs such as the gold-splashed Japanese laurels (Aucuba japonica cvs.), but the foliage of variegated plants that prefer brighter conditions may revert to plain green — more on this soon.
Like silver foliage in coastal gardens, masses of variegated leaves act as a great contrast or foil to brightly coloured flowers. This makes variegated plants particularly effective in annual and perennial borders. Plants like the variegated giant reed (Arundo donax ‘Variegata’) or the variegated water figwort (Scrophularia auriculata ‘Variegata’) can be just as impressive as any flowering plant and look even better when offset against dark flowers or deep green foliage that emphasises their variegations.
Brightening a dull fence with a variegated plant is difficult. Apart from the ivies, variegated climbers are rare. It would be great to be able to nip down to the nearest garden centre and buy a variegated wisteria like gold-splashed ‘Hagoromo Nishiki’ or the freckled ‘Nishiki’, but it’s just not possible. Instead, if you want a variegated climber while avoiding the possibly invasive ivies you’ll have to content yourself with the variegated jasmine (Jasminum officinale ‘Variegatum’) or the star jasmines (Trachelospermum jasminoides ‘Variegatum’ and ‘Tricolor’).
Reverting to green
Variegated plants usually start life as a variegated branch or small growth on an otherwise green-leaved plant. That growth is removed and the variegated cultivar is then vegetatively propagated and perpetuated.
But because the white and pale grey parts of their leaves lack the chlorophyll necessary for photosynthesis, variegated plants are often
less vigorous than their plain green counterparts. Consequently it’s not
surprising that, if grown in deep shade or when starved, drought stricken or
otherwise stressed, variegated foliage often shows a strong tendency to revert
to green. Reversion is usually just a survival mechanism: when the going gets
tough the plant has a better chance of survival with plain green leaves that
are best able to make use of their ability to photosynthesise light.
Occasionally variegations are simply unstable and may revert for no apparent
reason.
Whatever the cause, once reversion starts
it will usually continue unless the gardener intervenes. That means
keeping an eye open for branches with plain green leaves. Remove these twigs or
branches immediately, cutting them right back to the stem from which they are
growing. Any delay could cause problems because the reversion tends to speed up
as green leaves begin to outnumber the variegated ones.
Plant selection
New Zealand natives
Variegation seems to be common among New Zealand natives and has resulted in some very popular cultivars. The variegated form of Griselinia littoralis for example, known rather uninspiringly (like so many variegated plants) as ‘Variegata’, is far more widely cultivated than the plain green species. Flaxes (Phormium cvs.) too, display a huge range of variegation and foliage colour.
Coprosmas are probably the most widely grown variegated New Zealand plants. The small-leaved forms, such as C. × kirkii ‘Variegata’, ‘Kiwi Gold’, ‘Kiwi Silver’ and ‘Beatson’s Gold’ are superb groundcovers or dense twiggy shrubs. Although it’s probably the least widely grown, my favourite among these is ‘Beatson’s Gold’. It is a 2–2.5 m high shrub with olive green leaves that have a central dusky-gold blotch. Having grown it for over 10 years and seen how tough it is and how well it adapts to trimming, I can’t understand why it’s not more popular. ‘Beatson’s Gold’ is in many ways just as versatile as box — use it for hedging, topiary or anywhere a small-leaved densely-foliaged hardy evergreen shrub is desirable.
The large variegated coprosmas tend to be selections of the taupata (Coprosma repens). My favourite is ‘Taupata Gold’, but ‘Marble Queen’ and the multi-coloured ‘Pride’ are easier to find in the shops.
Pittosporums also tend towards variegation. I particularly like the variegated forms of Pittosporum crassifolium and P. eugenioides, but the many cultivars of P. tenuifolium show the greatest diversity. ‘Irene Paterson’ is the most obviously variegated, though it can be rather a weak plant. Cultivars with more green in their foliage, such as ‘Tandarra Gold’, ‘Silver Sheen’ and the subtly variegated ‘Limelight’ are generally better performers.
Other medium-sized variegated natives include Pseudopanax ‘Gold Splash’, a great tub plant; Dodonea viscosa ‘Moonbeam’, which needs shelter from drying winds or the leaf edges will brown; variegated kawa kawa (Macropiper excelsum ‘Variegata’); the many Lophomyrtus cultivars; and variegated hebes, such as H. × franciscana ‘Waireka’.
Variegation is also found among the large native plants. ‘Alba Variegatus’ is a karaka (Corynocarpus laevigata) cultivar that not only has boldly variegated foliage, but which also displays drupes that are also variegated until they finally mature to an overall golden-brown. There are two beautifully variegated forms of Hoheria populnea: ‘Variegata’ with yellow-centred leaves, and ‘Alba Variegata’ with white-edged foliage. There’s even a variegated pohutukawa (Metrosideros excelsa ‘Variegata’) with foliage bold enough to compete with the vivid red flowers.
One shade-loving native that has always been popular is the Chatham Island forget-me-not (Myosotidium hortensia), but being such a very dark-leaved plant it can get lost among a mass of deep green foliage. Well, that may be about to change because I’ve recently seen a variegated cultivar in a Christchurch wholesale nursery. It’s still in the early stages of propagation and is at least three years away from the market. It’s a striking plant and the flowers, a slightly lighter shade of blue than normal, really stand out against the cream, grey-green and deep green foliage.
Perennials
Of all the variegated plants, I find the perennials the most useful. That’s largely because of their versatility and adaptability — you can fit them in anywhere and they’re great space fillers. There’s also their ease of propagation to consider: most of them can simply be divided and before long you’ve got enough to start giving them away.
Variegation doesn’t just mean green and white foliage. There’s all manner of shades of green, grey, cream, yellow, gold and silver, and no plants display that variety more freely than the hostas. Because they’ve become so fashionable over the last decade or so we now have a huge range to choose from. It’s not inconceivable that you could make a very interesting and attractive woodland garden just from variegated hostas.
But for variety you’ll want something different. In sunny areas I’d start with the grasses. I’ve already mentioned the giant reed, but if that’s too large try some of the smaller variegated bamboos such as the golden-stemmed Pleioblastus humilis var. pumilus ‘Aurea’ (syn. Sasa pumila ‘Aurea’). Carex morrowii ‘Evergold’ and Hakonechloa macra ‘Alboaurea’, both Japanese grasses are relatively small and clump forming with bold enough variegations to really stand out.
Not a grass, but definitely grassy in appearance the variegated flag iris (Iris pseudacorus ‘Variegatus’) has the advantage of growing in either moist garden soil or in a few centimetres of water. It’s a strong grower though, so take care to plant it where its exuberance can be contained.
Among the more traditional herbaceous perennials I have several favourites. Disporum sessile ‘Variegatum’, from Japan and Sakhalin Island, could perhaps be overlooked among bolder perennials, but once you’ve seen its graceful habit and pendulous Solomon’s seal-like flowers I’m sure it will be in you top ten too. The same applies to the variegated figwort or water betony (Scrophularia auriculata ‘Variegata’) that I mentioned earlier. Descriptions and photographs don’t do it justice — it positively glows. Farfugium japonicum ‘Aureomaculata’ (syn Ligularia tussilaginea ‘Aureomaculata’) is, despite its rather tropical looks, a hardy perennial. Grow it as a foliage plant because, unlike its plain green-leaved cousin, it seems a little reluctant to produce its yellow daisy flowers.
Variegated ground cover perennials are probably the best way to brighten a dull corner; they seem to reflect light back onto the taller plants and structures above them. The silver-variegated dead nettle (Lamium maculatum ‘Silver Beacon’) is one of the best for this purpose and soon spreads to fill a considerable area. The variegated or golden lemon balm (Melissa officinalis ‘Aurea’), is also useful and its foliage is citron- scented. However, it can be rather invasive.
The pulmonarias are also superb ground covers or fillers for shade or partial shade. The degree of variegation differs with the cultivar. ‘Excalibur’ is one of the best, and presumably so-named because of its silver sword-shaped leaves. Others, such as ‘Sissinghurst White’ or Pulmonaria longifolia have simple white-spotted leaves, but are very effective nonetheless.
Shrubs and trees
There are so many variegated trees and shrubs that it’s hard to come up with favourites because new selections keep coming to mind. If I had to pick just one though, it would be the variegated form of the pagoda dogwood or green osier (Cornus alternifolia ‘Argentea’ [syn ‘Variegata’]). It’s simply so graceful with its near horizontal branches and light, airy foliage. The trouble is that it’s very difficult to propagate and consequently very rare. As an alternative you could try Cornus alba ‘Argenteomarginata’, but it’s not the same.
Maples would also be among my first choices. Acer platanoides ‘Drummondii’ and ‘Walderseei’, A. mono ‘Hoshiyadori, A. pseudoplatanus ‘Leopoldii’, A. palmatum ‘Dissectum Variegatum’ and A. negundo ‘Flamingo’ are all absolutely beautiful and display widely changing foliage colours over the growing season.
Equally beautiful among the large trees are the variegated smooth or field elm (Ulmus carpinifolia ‘Variegata’) and the yellow-variegated tulip tree (Liriodendron tulipifera ‘Aureomarginatum’).
Among the smaller trees the many forms of Chamaecyparis come to mind. They range from tiny mounds, such as C. pisifera ‘Snow’, through to 8–10m high trees. Junipers too, are conifers that frequently have foliage flecked with gold.
As a tree for year-round beauty it is hard to go past the variegated vanilla tree (Azara microphylla ‘Variegata’). It has bright creamy yellow foliage in spring that ages to gold than develops bronze tints in winter, then in spring its tiny flowers scent the whole garden. Its small cousin, A. integrifolia ‘Variegata’ lacks the strong scent but is nevertheless an interesting variegated shrub.
Of course, variegated plants can be more than just pretty. The variegated satinwood (Phebalium squameum ‘Illumination’ is one of the most widely grown hedging plants, a job for which it is well suited because of its very narrow upright growth habit.
Other worthwhile variegated large shrubs include the hollies (Ilex cvs.), Variegated Chinese privet (Ligustrum lucidum ‘Tricolor’), the variegated wild olives (Elaeagnus pungens cvs.) and the variegated false aralia (Fatsia japonica ‘Variegata’).
Deciduous shrubs are not so popular in our year-round gardens, but one that shows no sign of losing favour is Weigela florida ‘Variegata’. Not only does it have boldly variegated foliage and beautiful spring flowers, in some years it develops spectacular autumn colour.
Rhododendron and rose enthusiasts don’t miss out either. Rhododendron ‘President Roosevelt’ with its bright yellow-variegated foliage and tall trusses of red and white flowers is a common sight in spring, while for a real novelty try growing the rose ‘Curiosity’ — it certainly lives up to its name.
Of the smaller shrubs I think the variegated rock daphne (Daphne cneorum ‘Variegata) is absolutely charming. And while on the subject of daphnes, did you realise that the variegated form of the ubiquitous Daphne odora, ‘Aureomarginata, is actually hardier than the more common ‘Leucantha’? Well it is, so southern gardeners might like to try it.
So there we have it, just a few of the hundreds of variegated shrubs and trees that you have to choose from. Keep an eye open too for Abutilon megapotamicum ‘Variegatum’, a yellow-variegated form of the trailing abutilon; yellow-variegated box (Buxus sempervirens ‘Aureo Variegata’); Coronilla valentina ssp. glauca ‘Variegata’; Euonymus fortunei ‘Gracilis’, a neat little evergreen shrub; variegated Fuchsia fulgens, a form of a Mexican species that grows 1–3m tall; Grevillea rosmarinifolia ‘Variegata’; variegated myrtle; Hydrangea ‘Tricolor’; (Myrtus communis ‘Variegata’); variegated lily-of-the-valley shrub (Pieris japonica ‘Variegata’); and variegated mint bush (Prostanthera ovalifolia ‘Variegata’).
Warm areas
Gardeners in the frost-free areas may like to consider a few tender variegated plants. While you probably won’t succeed with crotons and Fijian fire plants may look rather dowdy, many tender plants will thrive if just kept away from frost.
The variegated shell ginger (Alpinia zerumbet [syns. A. nutans, A. speciosa] ‘Variegata’), has striped foliage, while pink snow bush (Breynia nivosa ‘Roseapicta’) has small leaves that display a range of colours. The variegated rubber trees such as Ficus elastica ‘Schrijveriana’ and ‘Variegata’ are likely to be shrubby rather than tree-like under New Zealand conditions, but that may be no bad thing. And for variegation with an edible pay-off there’s the variegated lemon (Citrus limon ‘Variegated Lemon’) a lemon with bright creamy yellow variegated foliage and fruit that is green-striped until mature.
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Oh, and the big question: why do plants have variegated foliage? Well, I’ve looked high and low and I can’t find the answer. In fact, I can’t even find a clue, let alone the answer. It certainly doesn’t do the plants any favours because it reduces their ability to photosynthesise. On the other hand, it can’t do them much harm because it’s a very common phenomenon. We should just be glad they do. After all, perhaps variety is the spice of life for plants, just as it is for gardeners.
Copyright Geoff Bryant
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