Category Archives: Plant collector

flowering this week, tried and true plants

Simple things – appreciating primula species

Many square metres of Primula helodoxa

Mark wasn’t particularly optimistic about the primula seedlings we were given some months ago. “We can’t do primulas well,” he said. I went away and thought about this and came back to him, pointing out that we can do Primula helodoxa rather too well, Primula obconica has stayed in one patch of garden for at least two decades despite minimal attention and the annual Primula malacoides pops up prettily around the place and would pop up everywhere if we didn’t restrict its spread. What he meant, I figured, was that we have not succeeded with the choice species like Primula vialii and the Inshriach hybrids which brought a range of different colours, did well initially and then just faded out.

Primula denticulata in the recently planted perennial meadow of the Iolanthe garden

More than one flower spike is forming in many of the plants which is a good sign.

This new primula is a wild form of  P. denticulata, so nothing too out of the ordinary or fussy.  It put up its first flowers a few months ago and, to my delight, is a pretty lilac blue. I am very hopeful it will do well here because it is a colour I really like. To be honest, it is more lilac than blue but that is fine. It has a good strong stem and holds its round flower head up well at 30 to 40cm above the foliage. What is particularly pleasing is that the stronger plants are putting up multiple flower heads. It is always encouraging to get a new plant and even better when you get given over 20 of them rather than buying a single plant and then trying to build it up. Time will tell if it settles in happily over several years and whether it is a suitable candidate for naturalising in meadow conditions but the early signs are good.

The only two polyanthus I kept on the left, Primula vulgare or the wild English primroe in a tiny bunch of nostalgia on the right

The primula family is huge with around 500 or more species. The English primrose, Primula vulgaris, was one of my English mother’s favourite plants in every garden she made – and in her lifetime she made many. I just have one patch of it because the foliage to flower ratio is rather too high in our mild climate but I like to keep it out of nostalgia. As a child, my mother encouraged me to pick flowers (always with long stems, she stressed, and the rule of thumb was that I could pick anything except the roses) and my bouquets were often primroses and grape hyacinths.

Primula malacoides – easy to pull out if it is in the wrong place but charming enough to allow it to gently seed around some areas

Polyanthus and auriculas also belong to the primula family. I am never sure whether I like auriculas. I can admire the curious flower markings but I am not sure how or where one would place them in a garden situation without having them look like a fake flower that was bought from The Warehouse. Maybe this is one of the reasons for that odd feature of the auricula theatre favoured by some UK gardeners – they couldn’t work out how to place them effectively as garden plants, either. Fortunately, this is an academic question here because auriculas are a plant that does way better in colder climates than ours.

Primula obconica has staying power here

Polyanthus are a cheap and cheerful late winter and early spring plant in many gardens. When our children were little, we would sometimes call in to a local hobby grower and let the children select the colours they liked to plant at home. Over time, I have cast out all polyanthus here except for a pure yellow one that I keep in one spot and a good performing white that I have in another area. They lack the refinement of the species that I now prefer; they need regular digging and dividing to keep them performing well and they tend to attract weevils. The weevil larvae show as wriggly white wormy things, usually about half a centimetre long. Years of nursery work instilled a fear of black vine weevils. Perfectly healthy-looking trees and shrubs in the nursery could suddenly flop overnight and forensic examination would reveal that the plants had been ringbarked by weevils just below the level of the potting mix. It took a lot of effort, changed practices, expense and the use of a rather strong chemical to eradicate weevils from the nursery. I am not keen on getting major infestations of these critters in the garden.

My rule of thumb is that I squish any white wriggly things I find in the garden soil. I don’t mind doing that for the new lilac blue prims if they settle in here for the long haul.

Primula denticulata – seedling grown so there will be variation in the flowers

Spot the difference

I was going to write a piece this week shouting that now IS the very time we should be talking about climate change, aimed at the Australian prime minister, Scott Morrison, who left his burning country to holiday in the cleaner air of Hawaii, declaring that now is not the time for knee-jerk reactions to a major drought and extreme fires and neither is it the time to talk about climate change.

But the majority of Australians voted that man and his government in this very year and I decided that maybe I would leave it to those voters to reflect upon their collective decision and respond to their own environmental crisis. Instead I will focus on flowers.

Hydrangea petiolaris, resplendent in full sun, although it has its roots on the cool side of the fence. Most climbers appreciate a cool root run.

Both the common climbing hydrangea, H. petiolaris, and the less common Schizophragma hydrangeoides are in full bloom here and I have never lined them up side by side to compare them. We produced both commercially in our nursery days but concentrated more on the allegedly more refined and desirable schizophragma. What were the differences, I wondered, in visual terms?

Hydrangea petiolaris to the left and the white and pink forms of Schizophragma hydrangeoides. Petiolaris looks creamier because it is an older flower grown in full sun. 

Not a whole lot, was the answer when I lined them up. The pink form of the schizophragma is  indubitably a different colour – rosy pink sepals, not white. H. petiolaris has more fertile flowers (the central tiny blooms on the lace-cap) and somewhat smaller outer petals (ray florets or sepals). It makes it appear a little bit heavier perhaps, than the light dancing of the sepals on the schizophragma. The hydrangea also has larger leaves overall. All of them have a light scent with a slight variation between the two species but nothing of great note.

Schizophragma hydrangeoides ‘Roseum’

Botanically, there is a difference. They are distinct species, though from similar parts of the world (woodland Asia, particularly Japan) and liking similar conditions. Schizophragma is nowhere near as common as H. petiolaris and has the reputation of being slow to establish. But I planted that petiolaris many years ago and it took several years to reach its stride, too. Mark reminds me that the reason he went for the schizophragma over petiolaris was because the latter would not set flowers on young plants.

Schizophragma hydrangeoides

Plantspeople and those with refined visual sensibilities will pick the difference. I prefer the lighter, more ethereal look of the schizophragma. But overall, I concluded that Mark’s ‘man on a galloping horse’ analogy applies. A man (or woman, presumably) passing on a galloping horse would not pick the difference. To be honest, most gardeners wouldn’t either. They are both lovely at their peak and well behaved as far as climbers go.

Seven long years to bloom and then it dies – Cardiocrinum giganteum

The giant Himalayan lilies are coming into bloom. Cardiocrinum giganteum. It is the biggest of the lily family, hailing from areas like Tibet, Bhutan, Assam, Myanmar, Nepal and Sikkim.  It feels a bit of a triumph that we now have this bulb naturalised here. We haven’t planted any for many years and just allow them to grow where they pop up from seed.

The largest lily of them all – Cardiocrinum giganteum

These are not lilies for the home gardener on a small urban section. The flower spikes often reach three metres here and have been recorded at up to five metres. Fortunately, the stem is such that they can hold themselves up.

Usually six years of foliage and in the seventh year, it puts up an astounding flower spike

The main obstacle for most gardeners is that the bulb takes about seven years before it flowers and then it dies. Fortunately it makes offshoots around the main bulb as well as setting seed but those offshoots can take another five years minimum before they flower and the seeds take seven years. These are not lilies for the impatient gardener. And, while very fragrant, the flowers are a long way up so unless you have a grove of plants flowering at the same time, you are unlikely to get the benefit of scent. In the intervening years, they just form a clump of large, heavy textured, heart-shaped leaves that are reasonably anonymous.

Typically, these plants need cool, open, woodland conditions with soils which never dry out and are rich in humus. Those are pretty specific conditions.

The top photo is one of those really, seriously peculiar plant combinations that are a characteristic of many New Zealand gardens – a self sown Cardiocrium giganteum from the Himalayas, flanked on the right by Pseudowintera colorata (commonly known here as the mountain horopita or pepper tree) with Dracophyllum latifolium behind (both NZ natives) and then what we know as Aloe bainseii but is now, apparently, Aloidendron barberae – the tree aloe from southern Africa. It is a veritable United Nations of plants here.

Waiting for hippeastrum flowers

We only have two species of hippeastrum in the garden. And one hybrid that bravely lives on in the rockery despite never receiving any praise and I don’t even appear to have photographed it. Most people probably grow the hybrids rather than the species and they are a genus that lends itself to novelty status – enormous flowers and some odd variations that are not necessarily creations of beauty.

Hippeastrum aulicum in the garden

Hippeastrum aulicum in particular is a mainstay of our early spring woodland. I have always described it as looking more like a Jacobean lily. Because it thrives with us, we have a lot of aulicum though we don’t get seed on the plants in the garden. Mark says this is because we are not hot enough but it will set seed if brought under cover.

Hippeastrum papilio. It has taken a while to increase it from a single bulb but we now have two patches like this.

It has taken a while to build up H. papilio but we are on track now with quite a few flowering in the same woodland conditions that suit H.aulicum. They certainly have a wow factor as a garden plant but we don’t get seed. Whether this is temperature related or they are not self-fertile, we do not know.

Mark wondered if we would get any interesting variations if he crossed the two species, while acknowledging that it was more a cross of convenience rather than one based on using the best possible parents. He did it so long ago that he can’t remember now which species he used as the seed-setter. Nor can I remember how many years it is since I grew tired of the pots of seedlings kicking around the nursery so took it upon myself to plant them out. Maybe about eight years?

The plants have done absolutely nothing in the garden except grow larger in the intervening years. Until this week! Two are flowering, well over a decade after the cross was made. Curiously, they are flowering before either of their parents: H. aulicum is only just putting its flower spikes up and is still some way off showing colour and it will be October before H. papilio blooms. I probably planted out a tray of 40 pots all up so there are a whole lot more to come. Eventually.

Nothing to get excited about

So what did we get? I was a bit underwhelmed by the first one. It only has two flowers to the stem and really just resembles a larger version of H. aulicum, maybe with more prominent green veining. I prefer the original species at this stage.

It is big – much bigger than its parents. And showy. But is it an improvement as a garden plant?

The second one is certainly larger, showing considerable hybrid vigour. The flower spike is over a metre tall and the spike has five big blooms opening on it. It is another red with green veining. So it looks as though it will be big and showy, if big and showy is how you like your bulbs. We would be happy with smaller and more interesting. Mark’s only comment so far has been that it never was a brilliant cross in the first place but it was just to get some variation in the garden.

Maybe the other 38 or so will show more interesting variations over the next few years? A large part of gardening is optimism.

I see there are about 90 species of hippeastrum though most of the hybrids are from just six of the species – including H. aulicum which surprised us, but not H. papilio.

The ornamental oxalis

The white form of Oxalis purpurea – the best of them all

Back in our nursery days, we had a large range of ornamental oxalis. I see in our old mailorder catalogues that we offered over 20 different varieties that we had in production at the time and I wrote extolling their autumn merits for several publications.

Twenty years on and the oxalis collection has refined itself down. It is the difference between gardening in containers and gardening in the soil. Some of those varieties were so delicate and touchy that we have lost them. Others needed to be kept confined because of their invasive proclivities. Some flowered prettily enough but their season was so short that it was hard to justify their place in the garden. I decided years ago that I was not going to fluff around with plants in containers. We have quite enough garden with many different micro-climates. If plants couldn’t perform in the garden, I didn’t have the time or inclination to nurture them in controlled conditions in containers.

These days, the oxalis we still have are the stand-out performers (and a few of the nasty weed ones that most of us battle – particularly the creeping weed which I think is Oxalis corniculata). The star has always been and still is the beautiful, well-behaved Oxalis purpurea alba. Large white flowers in abundance over a long period of time and not invasive. At this time of the year, I am more than happy to use it as ground cover in sunny positions. Oxalis flowers don’t open without the sun so they need to be in open conditions.

Oxalis purpurea nigrescens

O. purpurea is a variable species. The striking red-leafed form (O. purpurea nigrescens) with pink flowers comes a bit later and is invasive so needs to be kept confined. We also have a strong-growing (somewhat invasive) green-leafed form with very large pink flowers which is worth keeping and also has a long flowering season. Back in the days, I recall more than one person telling me that there was a red leafed form with the large white flowers but I have never seen it so I rather doubt its existence.

Oxalis luteola as runner-up in my best garden oxalis list

The standout yellow is Oxalis luteola. It, too, is well behaved and forms a gentle, non-invasive mat that flowers for a long time in mid- autumn, combining well without competing with other bulbs like the dwarf narcissi that are in growth but won’t flower until late winter and early spring. It leaves the rabbit-ear Oxalis fabaefolia in the dust for length of flowering time. Both have large, showy yellow flowers but the latter’s flowering time can be measured in days rather than weeks.

Oxalis massoniana

I am very fond of little Oxalis massoniana with its dainty apricot and yellow blooms but it needs a bit of nurturing to keep it going. The popular old candy-stripe O. versicolour is happy left to its own devices in the rockery but will not come into its season for a few weeks yet. It is the only one I know that looks more interesting when its flowers aren’t open because the striped buds disappear into a fairly ordinary white flower on sunny days.

I have hung onto the strong-growing O.eckloniana for its large lilac blooms but I keep it confined to a shallow pot sunk into the rockery. I could rustle up a few of the others from around the garden, like O.hirta in both lavender and pink, O. bowiei, O, lobata, the unusual double form of O. peduncularis  and O.polyphylla but they are not the star performers that luteola  and purpurea alba both are.

If you are into container gardening, a collection of different ornamental oxalis species give interest on a sunny terrace or door step from autumn to mid-winter. I saw somebody listing a whole range of different oxalis on Trade Me at one stage. In fact, it looked like somebody had bought our full collection all those years ago and kept it going so they are still around. If somebody offers you O. purpurea alba or O. luteola, don’t reject them just because they are oxalis. They are worth having.

Oh look! Here is a little display board I prepared earlier of under half of the oxalis that we used to grow