Plant Collector: Rhododendron sino nuttallii

Just beautiful - R. sino nuttallii

Just beautiful – R. sino nuttallii

Oh my, but we are besotted with the nuttallii rhododendrons which flower on even as November draws into December. We would rate these in the elite class as far as rhododendrons go. Not only are the heavy, waxy trumpets large and showy, they are also very fragrant. This one is planted on a bank which was a good decision because we can look down on it and the scent wafts up. Some of the others here are several metres above nose and eye level so the scent is a bit academic because they are best viewed from afar.

The foliage is large and heavily textured (bullate for the botanical or like heavy seersucker for those of a sewing disposition) and over time the main stems develop beautiful shiny, peeling bark in a cinnamon colour. These are large and open growing shrubs so do not fit the tight and tidy mould preferred by some.

‘Sino’ just means it is the Chinese form of the species, as opposed to R. nuttallii which is found in Tibet, North Burma and northern India. The Chinese form is bigger and showier and more sensitive to cold temperatures. These plants are rarely offered for sale though you can sometimes find some of the hybrids that have been bred from them.

Rhododendron sino nuttallii

Rhododendron sino nuttallii

First published in the Waikato Times and reprinted here with their permission.

Maples in the garden

???????????????????????????????Maples. They are acers, botanically speaking and there are plenty of them. They are often seen in gardens too, though the majority are probably what is commonly referred to as the Japanese maple – A. palmatum usually dissectum. There are multitudes of selected forms of this around, many of them carrying Japanese names. One of the reasons I have not written much about Japanese maples is because we don’t have names on many of the ones in our garden here and I have not gone to the trouble of working out which varieties they are. This failure is irrelevant when it comes to their role in the garden but it matters rather more when I write about them.

A random collection of maple leaves from around the garden

A random collection of maple leaves from around the garden

The world of maples goes well beyond those feathery Japanese ones. Maple syrup, dear readers does indeed come from maple trees, unless it is a synthetic version. Acer saccharum – the sugar maple – and that is the inspiration for the Canadian maple leaf emblem. It is also a major contributor to the autumn colours we associate with North America, along with Acer negundo. These are large landscape trees, not dainty little garden specimens though Acer negundo ‘Flamingo’, a pretty variegated form, is widely sold here and stays small enough to be a good option.

Autumn colour supreme

Autumn colour supreme

Maples are classified botanically and share certain characteristics including curious winged seeds which are designed to be dispersed by wind. In a gardening or landscape context, they have some common ground too. The foliage is soft so almost all of them are unsuitable for windy locations. They need adequate moisture levels in summer so are never going to like baking in hot, dry conditions. Many of them are happy in semi shade though some will lose their colour and become dull green in low light levels. Many colour up beautifully in autumn, even in milder climates.

Beyond that, rather than looking at pictures and deciding that you want a particular variety, this is one plant family where I suggest you go to your garden centre and read the plant labels. If you are really lucky, you may even strike someone there who knows about maples. You need to make decisions about whether you want a tree (and if so, what sized tree) or a little dwarf – often called patio maples. Also whether you want weeping or arching growth, or a more upright habit. Then there is the colour and whether you want one that keeps the same colour through spring and summer because some of them change colour as the leaves age.

I would counsel caution against buying too many red or burgundy foliaged maples. These are very dominant colours in the garden landscape and best used sparingly as feature plants. And if you feel compelled to plant a collection of maples, bear in mind that there may not be a huge difference in style between the dreaded conifer garden of the 1970s and the maple garden of more modern times. Enough said on that issue.
???????????????????????????????Besides feature trees which add to the skyline, we find the smaller growing maples combine well in a variety of situations. I really like the little weeping one we have planted with roses growing through it. It is a very pretty combination, especially with perennials also in flower. Pretty too are the ones in a semi- shaded bed with clematis scrambling around them and seasonal bulbs at their base. We have more upright forms in the rockery where we can keep their bases clear and they give good year-round form.
???????????????????????????????But one of the unsung delights of the smaller growing maples is that as they grow older, they can be gently encouraged into natural bonsai forms which give shape and interest in winter when they are fully naked. We do a bit of thinning and shaping but not much is required to make a feature of a maple with a good skeleton.

Plants which delight with distinctive, fresh spring foliage, last all summer, colour up in autumn and then have a really interesting shape in winter justify their garden position all year round. Add in their adaptability to a range of situations and their happy characteristic of combining with all sorts of other plants. It all comes down to making the right decisions on the variety and the garden position from the start. These are good staple plants to incorporate into any sheltered garden.

First published in the Waikato Times and reprinted here with their permission.

Garden Lore

“I have come to understand the unspeakable loveliness of a solitary spray of blossoms arranged as only a Japanese expert knows how to arrange it…and therefore I cannot think now of what we Occidentals call a “bouquet” as anything but a vulgar murdering of flowers, an outrage upon the colour-sense, a brutality, an abomination.”

Lafcardio Hearn, Glimpses of Unfamiliar Japan (1894).

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Dividing bearded irises
This will be the last call for irises on this page for a while, but if you have bearded irises, now is a good time to divide them. This should be done every few years to avoid clumps getting too congested, at which point they will stop flowering. Make sure you don’t damage the rhizomes as you dig them up. Wash them if need be to see what you are doing. Discard any mushy or damaged sections as well as the darker coloured older sections in the centre which have already done their dash. Fresh offsets (where leaves will now be growing) need to be about 8-10cm long before you cut them off so, if they are smaller, keep the parent rhizome with them. Cut the leaves back to about 15cm to reduce stress. Remove any spent flower spikes. Replant by spreading the roots but keeping the rhizome nestling just on top of the soil where it can bake in the sun.

Timing is not critical but done now, the iris has a chance to re-establish its roots and get a good footing before it has its winter rest. Bearded irises need full sun and excellent drainage to prosper.

First published in the Waikato Times and reprinted here with their permission.

Plant Collector: Tall Bearded Iris “Black Suited”

Iris 'Black Suited'

Iris ‘Black Suited’

In last week’s column, I included a photo of the black iris called “Anvil of Darkness”. This week it is the turn of the larger “Black Suited” to bloom and for wow factor, it sure has what it takes as a specimen bloom. It opened pure black but both these dark, velvety irises take on very deep purple tints as they age. These are novelty blooms in that black flowers are rare in nature and Mark is a bit suspicious of how well they stand out in the garden. I had been wondering about combining it with some white Siberian irises I have which flower at more or less the same time but he felt that was too obvious and it would look better surrounded by soft pastel colours, probably perennials rather than more irises.

Both these black irises were the work of an American breeder, Sterling Innerst, who was actually a primary school teacher who liked to breed irises in his leisure. He named 213 different new hybrids before his death in 2010 and I guess we might be grateful that the handsome “Black Suited” was not in fact named “Erotic Touch” or “Grobswitched” as two others were. “Black Suited” was first released in 2000 and any debt to original species is a fair way back in the past. He was crossing hybrids so it is a cross of “Before the Storm” with “Black Tie Affair”. The flower spike stands about 50cm.

I wondered whether breeding black irises was a recognised breeding quest but I see that the iris equivalent of the blue rose is in fact a pure red. It has yet to be attained.

First published in the Waikato Times and reprinted here with their permission.

Stripes, splashes and edges – variegated plants

Yellow variegated conifers are redolent of the 1960s and 70s but we have retained those that add a statement to the garden landscape

Yellow variegated conifers are redolent of the 1960s and 70s but we have retained those that add a statement to the garden landscape

New Zealand gardeners are not, in the main, huge fans of variegated foliage. There are exceptions – hostas being one – but as a general rule, we tend to avoid bi-coloured variations. This often surprises overseas gardeners, particularly British ones who are far more enamoured of such things.

I am sure it is related to the differing quality of light in this country. New Zealand is remarkable for its clear, bright light. In recent times, that light has been even less filtered due to the hole in the ozone layer. Those prized white, cream, yellow or pale variegations burn badly in the sunlight. If the sun doesn’t get them, then the winds often do and burned brown edges take the charm away.

It is different in countries with softer, more diffused light. Often such conditions go with lower sunshine hours and in a climate which is generally greyer, yellow plants and variegations can add a bright touch in the garden and landscape which is valued.

Variegations are usually sports – mutations, genetic aberrations, if you like. Sometimes it is the result of a virus. Most plants grow with one solid colour on the foliage. All sorts of plants can throw up a branch or stem with a variegation but most of these will be unstable and revert back to the original single block colour. Where a variegation can be isolated and increased by propagation, the resulting plants often the lack the vigour of the original plant.

Hideous variegated plants I have seen include a nasty variegated oleander in Spain. The mottled and margined leaf added nothing to what is a lovely flowering street tree in the right climate, in my opinion at least. There was a ghastly variegated spirea (a yellow and green leaf with murky pink flower) that we saw being sold widely in the UK. In this country, the top selling rhododendron for a number of years in the 80s was a mutant named President Roosevelt. Some of you may still have it in your gardens so stop reading now if you are going to take offence. It was the first plant I cut out when we bought the property across the road from where we now live. I do not think the yellow mid-rib to the leaf added anything but when you add a red and white variegated flower to green and gold foliage, it was all too much for me. But distinctive, so it sold.

We have retained the odd variegated yellow conifer here but only because they are handsome, established trees which make a contribution to the landscape. I can’t think that we would choose to plant them from scratch.

The variegated disporum lit up a dark area but proved altogether too invasive

The variegated disporum lit up a dark area but proved altogether too invasive

That said, in darker areas of the garden, the odd bit of variegated foliage can light up an area. It was for this reason that Mark planted the ground cover that I think is Disporum sessile variegatum. It’s pretty green and white foliage gave a lift in the shade. I have spent the better part of this week weeding it out because, unlike other disporums we grow (‘diaspora’, I keep calling them), this one was scarily invasive. It spread alarmingly, rampantly and through everything. We have retained only one small patch in a confined area. The rest is now in the compost heap. Plant this one at your peril. This variegated form is an exception to the rule in that, for us, it is much strong growing than the others we grow.

Farfugium tussilagineum argenteum looks good in shaded areas

Farfugium tussilagineum argenteum looks good in shaded areas

Other variegated shade plants we use – but in moderation – is a white edged form of Soloman Seal, a yellow striped renga renga lily (arthropodium), a handsome variegated crinum, farfugiums (which most readers will still know as ligularias) and, of course, hostas. But not all together. The secret to using plants with variegated foliage is to set them off with plenty of block-coloured foliage.

Offset variegated hostas with other plain coloured varieties for best effect

Offset variegated hostas with other plain coloured varieties for best effect

Nowhere is this more apparent than with hostas. Too often, people will only buy the fancy, variegated ones and I have never seen a good planting of a variegated hosta beside other variegated hostas, all different. But take the same hosta and put it beside some plain coloured foliages and it can add zing and star in its own right.

Most variegated plants lean to the “Look at me! Look at me!” sort of statement. If you are going to grow variegated plants, make sure that you use them so that they are the feature they want to be and don’t sit them alongside a medley of other plants also demanding to be the star. That becomes a jumble.

First published in the Waikato Times and reprinted here with their permission.