Sunday, February 24, 2013

I love the arrival of March.  It usually means the temperatures are on the way down and the weather seems more settled, although it also often heralds the arrival of autumn rains.  March starts the long slow festival of changing colour that the deciduous trees undergo as they prepare for winter, and the Head Gardener and I both have birthdays in March, although whether that is something to be happy about is a matter of debate.
What March also brings, very excitedly to me at least, is the start of the spring bulb selling season, with daffodils and tulips galore, but also a sprinkling of a bewildering range of other species.
It all starts with the close cousins, the anemones and ranunculus, superficially similar but quite different in many ways.  They are the first off the block because they are almost all raised in the Northern Hemisphere, and thus are available sooner than home-grown bulbs that require more processing.
Ranunculus are among the prettiest of all the spring flowering bulbs with a range of bright colours, delightful flower shape, and a wonderful succession of blooms from each tuber.  A bed or a pot of single coloured flowers is a dramatic sight, while the straight-stemmed flowers are perfect for picking and displaying in the house.  There are even some strains that have been specifically bred for the pot plant market, and flower at much lower height, although I have to say they seem to be missing some of the grace that makes ranunculus such fabulous garden plants.
When you buy ranunculus tubers they will be dormant, and very hard and dry.  To overcome this and ensure they kick into growth they could be popped into a paper bag and left in the refrigerator for a few weeks.   This will give them a slow wake up from their long slumber, and when they are removed from the cool they can be gently soaked overnight.  They can then be planted into a well drained potting mix or directly into the garden if a sunny spot with good drainage can be found.
The tubers consist are made up of claws connected to a central crown at the top – it is important that the claws should be planted downwards as the tuber will just rot if planted the wrong way around.
I find they do better if I start them in a potting tray, but even then they are a little bit prone to rotting off, so it probably pays to drench the potting mix with a fungicide.  They do like to grow in well fertilised soil, so it pays to work some bulb fertiliser into the bed before planting.  Good general purpose fertiliser will suffice if you do not have bulb fertiliser, and well composted animal manure is also good if worked in well before planting.   Watering can be a bit tricky as ranunculus do not like to grow in damp spoils, but they also do not like drying out, the leaves taking on a yellow cast if they do.
If you keep them well-fed and watered, ranunculus should be in flower for months, providing a long lasting display for the garden and the house alike.
In the distant past ranunculus had a brief period of popularity among the obsessive flower growers on the United Kingdom – along with tulips, anemones and gold-lace polyanthus, they were treasured for the perfection of the flowers.  In the case of the ranunculus, that perfection required multiple petals arranged in a globular fashion, each tipped with a contrasting colour.  These exotic beauties have long since died out, but garden ranunculus remain pretty, multi-petalled plants

Sunday, February 17, 2013

Brachyglottis compacta 

This week the spotlight has (literally) been on Castlepoint as the beachside community, and its many friends, has celebrated the centenary of the switching on of the iconic lighthouse that graces its reef.  The lighthouse was showing its true colours at times over the weekend, but at other times was lit with a variety of bright lights, surely making it a shipping hazard, as sailors, drawn by the display,  could have been lured siren-like onto the rocks.
Castlepoint is a wonderful place for a variety of social reasons, but for gardeners and lovers of native plants and wildlife, there are others reasons to venture out eastwards, as the reef and the remarkable castellated hill that Captain Cook called Castle Rock are home to some interesting and garden-worthy plants.
Prime among these is the Castlepoint groundsel, Brachyglottis compacta.  There are many species of Brachyglottis in New Zealand, among them a cluster of yellow flowering evergreen shrubs of coastal habits, but there are also inland, and even mountain species, the best known of which is the rangiora, B. repanda.
Castlepoint’s daisy  is a bushy, evergreen flowering shrub of low growing habits –  about a metre or so – and the only place it is found in the world is on the limestone cliffs at the beach.  It has oval shaped leaves about 2–4 cm long which are green above and white below, with slightly toothed edges. The flowers are yellow and appear in summer. 
As you would expect this is a brilliant plant for dry places, and will flourish through the worst Wairarapa droughts in hot sunny places, its golden flowers following by wispy white seedheads.
Wairarapa is also home to the similar, but subtly  different, B. greyii, which is found in coastal areas to the south, from about Flat Point around to the mouth of the Orongorongo river.   It has slightly greyer leaves, but retains the silvery down on the underside, and gives a greyer appearance that the Castlepoint species.  It has an even better display of golden flowers making this particular species popular overseas.  This is another great shrub that does very well in hot sun, coping well with poor soils.  We have struggled a bit this with plant as it is planted in rubbish soil, a piece of land previous owners filled with road scrapings.  The soil is very heavy and wet in winter, and these plants are not keen on those conditions.
As you might expect, these species have been crossed, and they are the parents of a number of interesting hybrids including the very popular Brachyglottis ‘Sunshine’, which is another very hardy form with grey leaves and a super abundance of yellow flowers.  Overseas there is a variegated form of this plant but it is hard to see how it could be an improvement.  ‘Otari Cloud’ is a similar hybrid, and has heaps of bright golden flowers over grey foliage.
I suspect these plants have become very muddled in the horticulture trade and buying any one of them might mean you end up with one of the others!
There is one form that is quite different – Brachyglottis ‘Leith Gold’ is a Dunedin-raised form with a mix of the attributes of its parents, having  large leaves that are similar in size to rangiora but  having the colour and texture of B.greyii. This interesting plant has a fairly open habit, again halfway between its parents, and it carries panicles of small yellow flowers, intermediate in size between the tiny flowers of rangiora, and the larger flowers of the Wairarapa species.   To get the biggest leaves it is necessary to grow this in some shade, but it will cope with full sun otherwise.

Sunday, February 10, 2013

Post fire ruminations

As if the summer season was not hot enough for gardeners and those in the nursery trade, my friends Laurie and Carol down at the Garden Barn in High Street decided to make things even hotter last weekend, with an unplanned bonfire in their potting shed.  Fortunately no-one was hurt in the fire (although Laurie was out of earshot when it started and caused some concern) and, although there was a fair bit of damage, they will bounce back.  This couple know only one way to cope with something like the fire – they will roll up their sleeves, knuckle down and repair the damage.
Being of a naturally cheeky disposition, I have decided to give them some choices for their autumn sale, some suggestions of varieties they may want to run specials on.
First up, of course, are the Cotinus, or as most of us call them, “Smoke Bushes”.   There are a couple of different groups of these, the American and European forms. The European species, C. coggygria, probably deserves the common name more because it has plumes of misty purplish flowers in early summer which fade as summer progresses and become even smokier.  Their foliage colours up in the autumn but the display is nowhere near as good as that of their American cousins.  One form, though, has amazing foliage right through the growing season, the deeply coloured form called ‘Royal Purple’  which has deep wine purple coloured leaves with a shiny surface. It has gigantic flower heads of light mauve over summer, and then for autumn colours up almost as well as the American forms.
The American C. obovatus is taller growing that its European relative, and does not have the same amount of flowers nor the same degree of smokiness.  Perhaps you could call it the politically correct smoke bush – the smokefree smoke bush.   However, what it lacks in flower power it more than makes up for with foliage display, especially in the autumn when the leaves take on hues of orange, scarlet and purple giving a startling display.  I think this may be the best autumn foliage display of any medium sized shrub.
These are relatively easily-grown plants, preferring a sunny situation and cool, free-draining soil.  They do not like the soil to be over-rich, and they certainly do not need fertiliser applied often, because when they are grown in rich soil they grow rather coarsely and do not colour up so well.  However, they do respond very well to trimming and shaping, the neater bushes giving better foliage displays.
I do not even know if my friends stock this next plant, a striking evergreen tree from across the ditch, but perhaps they will soon.  I am referring to the glorious Firewheel Tree, Stenocarpus sinuatus.  This flamboyant tree, native to the coastal forests of Queensland, is frost tender, but I have seen it growing very well in Napier, so I am sure you could get away with it in warm areas of Wairarapa, especially near the coast.
It has unusual foliage – the leaves are glossy green and wavy – and has spectacularly showy bright orange red flowers at this time. The flowers radiate out from a central point, giving the impression of a spoked wheel, and last into the autumn.  This is a great specimen tree (it grows about ten metres high) if you have a frost-free site.

Wednesday, February 06, 2013

Albizia julbrissin 'Rosea'

This past week has been a trying one for gardeners, with unrelenting heat, temperatures of over 30 degrees for days on end, and little sign of any respite. As I write this on Sunday it is almost unbearably hot, with not even a breeze to cool things down. Then forecasters are saying we might have a windy day tomorrow, with the chance of rain from the west, so I guess there is a fair chance we will not even see much from that quarter.
It seems to me the only place to be in the garden at the moment is in the shade, under an umbrella or in the shadow of a mature shelter tree.
I visited a garden in the south Wairarapa recently, a garden that featured an ancient oak tree – well over a hundred years old I would think. It had been well looked after and I could see signs of recent tree doctor work, with carefully cut limbs visible. The rest of the garden had obviously been “made over” a few years ago, and featured a couple of clusters of semi-mature shade trees, most welcome in the heat of a Martinborough summer.

The first of these was a grouping of the charmingly pink-flowered Albizia julbrissin ‘Rosea’.
This deciduous tree has the most graceful fern-like leaves through summer, and then pink to red fluffy
flowers that feature long silky stamens that give rise to its common name, Silk Tree. This is a quick
growing tree, with a delicate arching growth habit so that it even looks attractive even when without

It is perfect as a shade tree as it does not cast a dense shade like a beech tree – in fact, it creates a
lovely filtered shade and it is easy to establish a garden underneath it. It is also a relatively mess-free
option for the garden, as the fine leaves rapidly disintegrate in the autumn, making it easy to keep clean and tidy. Actually, the leaves are so tiny they would probably blow away in a typical Wairarapa

Sometimes this tree sets seed – it is a legume and has long pods with large seeds within. In some parts of the northern North Island and in the nelson area it has become sparsely naturalised, so think about planting this if you live in a warm costal area where it might get out of the garden and into the