Sunday, July 26, 2009

Cool weather bulbs

At this time of the year a few fine days make all the difference to how we feel. After weeks of being cooped up in our houses it is really great to be able to wander around the garden, and maybe even accomplish a little desultory weeding. And there are always little treasures to be found as some plants seem to shake themselves out of their winter slumber at the first sign of any warmth.
It should not be a surprise that the snowdrops are among the first bulbs to appear, as their name gives an indication they flower in the middle of cold times. I have often seen photographs of Galanthus, the botanical name for these white beauties, flowering through a break in a European snow drift, but I have to say it is not something I have seen in real life in our more temperate clime.
Early this morning I snuck down to my garden through lawn-crunching frost, to see what the snowdrops in flower at the moment looked like with frost (as close to snow as I am going to get in Wairarapa) but the effect was rather disappointing. I was up earlier than the flowers – they have enough sense to stay closed up in the cold of the early morning, only opening when the sun is warmer later in the day.
There are relatively few species of Galanthus – only 20 or so – but there are many different forms and varieties which are especially popular in the Northern Hemisphere, where their hardiness and ability to flower when no other bulbs are out, is treasured. There is even a name for those who love snowdrops – Galanthophile!
By far the most popular species is the Common Snowdrop, Galanthus nivalis, This is a very widespread species, with wild populations from Russia across to Spain and Sicily. It is also found in the countryside in Britain but these plants are thought to be naturalised rather than naturally occurring. In the wild they mainly grow in woodland and alongside streams, an indication that they prefer humus-rich soil and do not like to dry out.
Florally all snowdrops are remarkably similar – they each have three outer petals that splay out when open, with a ring of smaller inner petals in a tube, each of these inner petals marked with a prominent green spot. There are variations on the theme – in some species the spots are almost contiguous – and many interspecific hybrids.
With some a small amount of variation to play with it is remarkable that plant breeders have played with these plant so extensively, but there are over 500 varieties registered, a truly staggering amount. I cannot imagine how anyone could say with certainty which variety is which without extensive knowledge

Sunday, July 19, 2009


Even in the depths of winter there are joys to be wrought from the winter garden. There are the subtle flowers of winter sweet and Daphne bholua, whose charms, very much in a minor key, would be lost in the cacophony of spring. There are the subdued colours of those under rated perennials, the Winter Roses, members of the Hellebore family. There are also the tiny bulbs that grace the coldest months of the year – the perky little Crocus chrysanthus hybrids, with their sparkling little flowers, and the joyous little reticulate irises, their bright flowers popping up among the grassy foliage.
Then there are the exuberant winter flowering bedding plants – the pansies, poppies, primulas and polyanthus – all of them valuable tools for bring a bit of cheer to what can be a drear time in the garden.
Pansies have been on a roll for the past decade or so, and have surely taken over as the prime flower for this time of the year, and they are deservedly popular. Be careful though – there are many dark forms and the flowers just seem to disappear among the foliage in these darker times of the year. Stick to the lighter colours – the yellows, the pinks and the light blues.
The bedding primulas, mainly forms of the fairy primrose, P. malacoides, are extra valuable as they provide a light effect with their tiers of small flowers. I would not be without some of the white forms in my garden each winter. Poppies I could not live without – their simple flowers also seem to be somehow sophisticated.
But polyanthus hold a special place in my heart. They are one of the plants I remember best from my mother’s garden, and over the years I have grown many varieties, both commercially and for my own fun.
They were originally bred from the simple yellow primrose that grows wild in the hedgerows of England, its light yellow flowers of good size held singly on each stem. It is likely the polyanthus is derived from the oxlip, a hybrid from a primrose/cowslip cross. The cowslip is also yellow flowered, but each stem holds a head of smaller flowers. The oxlip is an intermediate form, with flowers in clusters, each flower between the cowslip and primrose in size. Other Primula species have been involved in the complicated breeding of these winter treasures, resulting in a bewildering range of colours and patterns.
The strongest growing polyanthus I remember from my mother’s garden was the old pale yellow form with deep yellow throat. It was so vigorous the foliage almost looked cabbage like. It was not perhaps the most attractive colour but en masse it looked wonderful. It also had the delightful scent that only yellow forms seem to have.
The big breakthrough with polyanthus came with the introduction of the Pacific Giants strain, originally bred in California. They were uniformly large flowered, had a good range of clear colours and were great performers – for their first year. Perhaps they would perform as perennials in their homeland, but in anything other than the mild climates of California, they struggled to live through for a second year.
From there things only got worse, at least in terms of perenniality. The breeders took up improving Pacific Giants until they came to dominate the seed and bedding markets. Almost all the plants sold in punnets in New Zealand are Pacific Giants, usually from Japanese-raised seed strains. They are good, reliable plants, and you can be sure you will get a good garden display. The bigger garden centres will have these single colours if that is your preference.

Sunday, July 12, 2009

PCNI seedlings

This is the time of the year I love. The Pacific Coast native irises (PCNI) – native to the United States, that is – are germinating.
It is always exciting to see the little children that one has carefully planned popping up through the soil. As always, I have far more seedlings than I can possibly plant out, so I will have to do some culling at the time I prick the seedlings out. At this stage, it is just fun to look at the grassy foliage of the new seedlings, and then come back here and look up the breeding books, that will give clues as to why particular crosses were made.
Just as importantly, this year’s divisions seem to have worked well too. I have been under some pressure to start naming and releasing some of my seedlings, as PNCIs are so difficult to find in New Zealand. I am keen to ensure they are plants that will shift well, as the PCNI have a bad reputation of not shifting easily. I divided my ten favourite plants, with at least ten divisions of each, about three months ago. So far, all seem to be going well, so I have my fingers crossed.

Yum, yum -yams and other oxalis

Unlike most gardeners, I have a love/hate relationship with Oxalis. Most of us have an out-and-out hate relationship with the many species of this widespread genus. We find them forever trying to take over our vegetable gardens by burying their many corms deep in the soil, or we find them steadily encroaching underneath the fence from the neighbours garden. Other species are persistent weeds in acid soils in lawns, while yet others make pests of themselves in container-grown plants.
So how could I have any kind of positive relationship with them?
There is one species I could hardly live without over winter – Oxalis tuberosa. This is an interesting plant from South America, where very many Oxalis species are found. It has the shamrock shaped leaves that many members of the family are blessed with, and it is a reliable grower throughout most of our region, although the tops are slightly frost tender.
It is, of course, the vegetable crop that most of the world calls oka, but which we Kiwis call the yam – not to be confused with the tropical crop that is also known as the yam.
As you might expect of an oxalis, this plant is relatively easy to grow, even though it does need a long growing season. The little tubers are best planted once the weather has warmed up, perhaps in late October or early November, at the same time we are all planting our other summer-growing tender crops. They are best planted in raised rows, similar to potatoes as they flourish in light, free draining soil. They are good feeders so it pays to work in some potato fertiliser at the time of planting, but they prefer a slightly acidic soil (you will not be surprised to learn, as they do, of course, contain oxalic acid) so you can go easy on the lime.
They need to be grown as long as possible; the bulbs are not produced until the night length is the same as the day length. They will require watering over the driest of our eastern summers, but seem to be relatively pest free. They will be ready to harvest when the tops dry off, usually in late March or April.
I have a small collection of some of the many decorative Oxalis species, largely in terracotta pots. At this time of the year the various forms of O. pupurpea are at their best. This is another South American species, from Chile, and is grown for its attractive winter flowers. There are a number of forms available in New Zealand. The one I like best is a purple foliaged variety (which I assume gave the plant its name) which I have seen described as ‘Nigrescens’ but I am not sure it is not the same forms grown in the rest of the world as ‘Garnet’. The deep leaves are wonderfully offset by the glowing pink flowers. These flowers are very difficult to accurately capture – they have a shiny gloss and the flowers always appear lighter in photographs than they do in the garden.
I grow two other forms of O. purpurea, with (oddly enough) green leaves, one with glowing white flowers, the other with shining pink flowers. There are yellow and cream forms of this species too, but I have not grown them.

Sunday, July 05, 2009

Robinson Park

It has been an interesting gardening week, even though the weather has been terrible. These weeks with rain every day do not do a lot for the gardening spirit, but I did manage to get one or two important jobs done, none more so than my annual pilgrimage to a small local park. The reserve was named in honour of the well-known plantsman and plant breeder Laurie Robinson and his family have taken it upon themselves to rejuvenate it.
For some years the reserve was allowed to become slightly overgrown, and a jungle of unattractive trees and shrubs established themselves along the southern boundary. For four years the family had been cleaning the park up and replanting the fresh ground with a variety of native trees and shrubs.
I was delighted to be asked to be part of the team that does the planting.
One of my earliest horticultural memories is of Laurie Robinson spending an hour one Saturday morning, giving me a tour around his nursery and showing off some of his special plants. He took me into a secluded private area where he was bulking up some special red flaxes, the variety that was eventually released as ‘Ruby Dazzler’. It was nothing like the very modern flax varieties, with their mix of brown, pink, cream and yellow – it was purple leaved with a flash of red – sometimes. It was not the most stable of plants, and often reverted to just purple. I do not think it is on offer in any new Zealand nursery today.
I was thinking about my memories of Laurie as we planted another hundred or so shrubs into the embankment on Saturday. He would have approved of what we were planting, but many people would not be happy there was a fair sprinkling of modern cultivars among them. Many people would prefer that ‘native’ plantings were confined to naturally occurring species, and that no cultivars would be allowed.
Others go a step further, insisting that only ‘eco-sourced’ material should be used. Plants are only raised by seed, not by cutting, and the seed has to be gathered from the closest possible naturally occurring stand.
This is an important concept when you are considering revegetation projects, as there is considerable genetic variation between different strains of the same species. Some plants, kowhai being a great example, are very widely divergent throughout New Zealand, and they are also very promiscuous – they will readily cross with each other. If we used a west Auckland species, for example, in a major rural planting, we risk bringing a new set of genetic factors into the local population.
There are some examples of some plants that could have an influence on their environment. I am sure botanists are worried about the widespread planting of the strong-growing Renga lily, Arthropodium ‘Matapouri Bay’. This has successfully colonised the nursery industry and is planted extensively throughout much of the country. It will now be spreading its Northland genes through all sorts of other wild populations, perhaps changing them forever.
Having said all that, I am sure we are doing the right thing by planting cultivars into the rejuvenated Robinson Park. We are not undertaking a revegetation project, we are creating a garden and the hybrid Hebes, Coprosmas, and even the golden totara, all look in place.