Garden Lore

Decorum is the refinement of propriety. It is in order to procure stable-dung for hot-beds; it is proper to do this at all times when it is wanted, but it is decorous to have the work performed early in the morning, that the putrescent vapours and dropping litter may not prove offensive to the master of the garden, should he, or any of his family or friends, visit the scene.

John Claudius Loudon Encyclopedia of Gardening (1822)

Urban paving
Urban paving

How to cope with the escalating demand for off street parking is a major urban issue. The severe flooding that assails the United Kingdom with ever-increasing regularity has in part been attributed to the problems of urbanisation and increasing run-off. Water has to go somewhere and if it cannot be absorbed into the ground because of concrete and tarmac, it will either pond, flood or flow until it finds somewhere to go. Urban stormwater systems are not built to drain all the water away, merely the excess water.

There are commercial products designed to give a firm base for car parking while still allowing drainage and ground absorption. Laid properly, the area can still be mowed or raked. Even sealed areas need maintenance, whether by sweeping or the use of a leaf blower. This midway position is a much sounder option environmentally, as well as being softer to the eye than expanses of seal.

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

Digging and dividing clivias

???????????????????????????????1) Clivias are wonderfully adaptable plants for mild climates. Their ability to thrive in hard conditions, even in relatively deep shade and with a regime of near total neglect makes them an obliging garden plant, once they are established. They don’t like frost but woodland conditions will protect them. The reason they are seen as expensive and choice is because they take years to reach a saleable grade, not that they are difficult. However, given time, clumps can get very large and yield many divisions for replanting.

???????????????????????????????2) It doesn’t seem to matter when you divide them, though it would probably pay to avoid dry mid-summer. Like most perennials, they respond well to lifting, dividing and being replanted in ground which has been freshly dug over. The clumps can be large and heavy but this one was small enough to get out as one. Get as much of the root system with it as you can.

???????????????????????????????3) I hosed the clump so it was easier to see and to show what the base looks like, but this is not necessary. The fleshy base is easily cut with a garden knife or a spade. It is easier to control what you are doing with a knife and to make sure that each division has roots attached. If you try and pull them apart by hand, you are more likely to end up with a tuft of leaves and no base.

???????????????????????????????4) It pays to reduce the volume of foliage – this reduces stress on the plant which has undergone considerable disturbance and root damage. I took off about half the leaves where the root systems looked small.

???????????????????????????????5) I dug over the area where the clump had been growing before replanting, incorporating the leaf litter that was lying around. Fertilise lightly if you wish and spread compost to enrich the soil and act as mulch.

???????????????????????????????6) In digging over, I found the missing rake head from many years ago when the area was first planted. It is a bit like trowels and secateurs in the compost heap but they usually reappear within the year (albeit in just as poor condition).

Published in the Waikato Times and reprinted here with their permission.

Garden Lore

“Few lend (but fools)
Their working Tools.”

Thomas Tusser Hundreth Good Pointes of Husbandrie (1557)

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Garden Lore: Winter Pruning

Winter and early spring are the optimum pruning times for most plants. Because the act of cutting back can stimulate plants into growth, timing can be important. Close to the coast, we only get light frosts so we never have to worry too much. But if you are used to waking to white ground and ice on puddles, hold back until the end of the month and leave the hydrangeas and roses until last.

Grapevines, raspberries – indeed all the brambles – and kiwi fruit need annual pruning or they will swamp you with their rampant growth. While pruning is recommended for most fruit trees, it doesn’t usually matter if you skip a year or two.

Always prune wisterias. They are as determined and rampant as kiwifruit. Roses will survive without pruning – although you may rue the day if you allow climbing ones free range and they look better for some care. Hydrangeas are pruned to increase flower size and to stop bushes getting too big. They will still bloom if you don’t prune them.

The critical piece of information you need is whether plants flower or fruit on last season’s new growth or on the new growth that they are preparing to make this spring. If is last year’s growth, as in hydrangeas, wisteria and raspberries, if you cut too hard, you simply won’t get any flowers or fruit this spring. Roses flower on fresh growth so you are pruning for shape and health and can cut back very hard. The same goes for grape vines. One size does not fit all in this matter.

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

Plant Collector: Rhododendron augustinii

Rhododendron augustinii

Rhododendron augustinii

I had to pick the flowers to photograph because I was too embarrassed to show the very poor foliage in its garden setting. R. augustinii is a lovely lilac, as close to blue as rhododendrons get. I think it is delightful in bloom, which is why we continue to give it garden space even though the plant itself leaves a lot to be desired in our conditions. We used to produce two different clones commercially for rhododendron collectors because it is highly prized. I planted several out at the time but I think this is the last one. It is much assailed by the bronze beetles which are attempting to eat it to death. Every leaf – and there aren’t that many of them – is badly notched. The beetle is worse in the shade but if we had this plant in full sun, it would likely up and die on us even faster.

It originates from the Chinese areas of Szechuan and Yunnan, along with southern Tibet where the climate will be both drier and colder in winter than here. It was named for Augustine Henry (1857-1930) who was a medical officer in Chinese Customs but presumably keen on plants because he moved on to be Professor in Forestry in Dublin. The flowering is unusually early this year. It normally blooms in early October but sometimes plants can get a little out of sync with the seasons.

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

“My tree will stop growing when it reaches 3 metres, won’t it?”

This ginkgo tree on the corner of Hall and Williams Streets in Cambridge gives lie to the 2.5 metre claim, though it is over 10 years of age. (Photo: Michael Jeans)

This ginkgo tree on the corner of Hall and Williams Streets in Cambridge gives lie to the 2.5 metre claim, though it is over 10 years of age. (Photo: Michael Jeans)

I am still chuckling. While I was preparing the recent column on ginkgo trees, a friend commented that she had one at the bottom of her garden and very pretty it is, too. Knowing she lives on a small town section, I replied that I hoped she had allowed plenty of room for it to grow. No, she assured me. She had looked it up and it only gets to 2.5 metres.

Raising my eyebrows, I sent her the Wikipedia link which declares ginkgo trees in the 20 to 35 metre range, with some specimens in China known to have reached 50 metres. I could feel her blench, even down the internet cable. It turns out that the internet site she drew her information from was a nursery selling the plants which stated 2.5 metres high in 10 years. Ginkgos are pretty slow growing but we would rate 2.5 metres as very conservative. We would expect that in 5 years here. And even in our nursery days, I do not think we would ever have declared a potentially huge tree as a suitable option for small, town gardens.

For as long as I can remember, the convention in this country has been to declare sizes on plant labels based on an average expectation of growth in 10 years. Problems come when the person writing the label may never even have seen the plant at 10 years of age, let alone 20, 30 or 40 years. We have always understood that the 10 year estimate came because that is the usual life expectancy of a plant in a New Zealand garden but I have no idea if that is true. The cynic in me says that it is more likely to be that customers would be frightened off purchases if they knew the real potential size of many trees and shrubs. Years ago, I wrote a series of columns on large, middle sized and small trees for gardens and a colleague chided me. I should not give mature sizes, she told me, because if customers knew those, they would never buy the plant.

As I mentioned recently in Garden Lore, it is easy enough to plant small specimens but if they outgrow their allotted space and become a problem, it can be very difficult and extremely expensive to get rid of them. It is also such a pity, particularly with trees. How much better is it to get the selection right from the start, so they can bravely grow on and reach their potential through the decades?

The problem often lies with impatient gardeners or home owners. Dear reader, Sod’s Law says that if a plant grows rapidly to the 3 metres you want, it is either very brittle and won’t last long, or it will continue growing to a much larger size, although the growth rate may slow. It is not going to reach the height you want and obligingly stay that size.

Experienced gardeners know that declared sizes are an inexact business at the best of times. A huge amount depends on conditions – sun, shade, wind, temperature, drainage, soil type and other variables. Geography plays a big part, both across the world and even within New Zealand. Plants grow more slowly and tend to stay more compact in colder climates.

Magnolia Iolanthe is not going to stop growing when it has reached 2 or 3 metres

Magnolia Iolanthe is not going to stop growing when it has reached 2 or 3 metres

I suggest you seek your advice from a number of different sources. Don’t accept a 10 year height as a final height and don’t expect that to be 100% accurate in your situation. It is only a guide and some guides are more accurate than others. We once found our magnificent Magnolia Iolanthe declared as a two metre high tree in a retail outlet.

If you want a tree that is going to be a focal point, consider spending more and buying an advanced grade specimen. You are paying to get a jump of several years in growth and that can make quite a difference in a small garden if you want instant impact. But keep to the slow growing varieties which will stay smaller. It may look as if you are getting more bangs for your buck if you buy a larger, fast growing one but really, you are just buying a vegetable time bomb.

Where space is limited, take potential width into account as well as height. A multi stemmed plant will generally be much wider than one with a single leader. Width can be a greater problem than height.

A mature Camellia Tiny Star makes an almost perfect small tree but it takes many years to get there

A mature Camellia Tiny Star makes an almost perfect small tree but it takes many years to get there

I would rate Camellia Tiny Star as close to perfection in a small tree – single trunked, gentle shade, evergreen, small foliage and plenty of tiny flowers, doesn’t get diseased, needs no maintenance and has reached its full potential. The downside is that it took a lot more than 5 years to get there.

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