Mothers' diaries, space and silver birches


I have been thinking about giving plants space to grow. In part, this has come because of the mothers’ gardening diaries which I wrote about in my last column and differing views therein on the matter.

In our garden we have an area we refer to as The Park. It is about four acres, planted out in various trees, both flowering and evergreen, many rhododendrons and assorted other woody plants with mown grass beneath and a meandering stream and ponds. It is very colourful in springtime and restful and green at other times. It has been a deliberate decision by Mark not to plant the stream edge densely but to work on the natural English look and have just occasional drifts of bog plants. This, I might say, only works in our eyes if one is willing to weedeat the grass which goes down to the water edge. A swathe of brown edging caused by using weedkiller instead is definitely not the look we are after.

Mark has chosen not to underplant most of the trees and shrubs. So it was interesting to read his mother’s account of planning and planting this area. In 1953, she wrote: “Under the house we made our rhododendron dell…. and planted the rhodos we had been importing…. We have allowed 12 feet apart in every way. The rhodos in Pukekura Park have to be shifted. They are only 6 or 7 feet apart and are growing into each other.”

I have been told by others that the wisdom of the New Zealand Rhododendron Association at the time (a very influential body in the gardening scene back then) was strongly of the view that rhododendrons are best planted singly in splendid isolation with no underplanting. There may be some logic in this approach in that they are a surface rooting plant and if they are heavily underplanted then they are having to compete for nourishment, root space and moisture.

My mother was itching to unleash herself on this park area – an ambition which she was never to fulfil. A strong advocate of the English cottage garden, she did not like trees and shrubs in splendid isolation. She wanted to turn the park area into a giant mixed border. In the late eighties she wrote a diary entry headed up: “Tikorangi. Some suggestions for Mark’s Park”. What follows is a list of every rampant perennial likely to fill vast areas (out of control pretty weeds, basically, like dicentra eximia and jasmines) and she even has a section entitled “Triffids to furnish between large rhodos”. I admit to some relief that we curbed her desire to leave us with a legacy of out of control triffids.

I have no doubt that in the early years, our park probably looked like a random dotting of smallish plants with no great design. Five decades on, it is park-like. Mature trees and shrubs with open spaces and room for the plants to grow naturally without competition. Over the years, Mark has taken great care to protect vistas and to create some continuity of flow for both the eyes and the feet so it is not random placement. Indeed, he is very cautious about planting new trees and shrubs in the area and it takes him a long time to place them. In no way is it a case of here is a space. Let’s fill it. And with maturity, it has become probably the most commonly admired part of the spring garden. I must have been told a hundred times that it is so nice to see plants with space to grow, able to be viewed in their entirety and that the sense of space and openness is delightful and soothing.

In this area, I think my vote rests with Mark’s parents, not my mother.

Do not get me wrong. I am not saying that all gardens should look like this. In other styles of gardening (which we use in other areas), dense planting is what is required. Mixed borders, herbaceous borders, cottage gardening, even some woodland gardening all depend on being full of billowing vegetation and flowers with no soil visible. The problem here is to prevent the rampant plants from smothering their smaller cousins and to allow plants to grow without suffering from heavy competition. Otherwise only the strong survive and not all treasures are strong growers.

Most of us overplant heavily in new gardens. The desire is strong to see a garden looking full and furnished quickly. But unless you sell up and move on, there comes a time when you need to be ruthless about the overplanting and start cutting out. I am watching friends struggle with this problem. In a garden which was heavily planted and had instant wow factor a decade ago, the effect now is of ever diminishing open space, leggy plants drawn to the light and too many plants looking hard done by. They really need to go through and cut out fifty percent (literally – every second plant) to give the garden space to grow on to the next stage of maturity but they are not brave enough to take such drastic action.

Not many gardeners have a view as longterm as that of my late parents in law when they planted out our park at the start of the fifties.

On another topic entirely, we were interested to read an article recently sounding very loud alarm bells about silver birches. Recent research has established that they are a major cause of human allergies. Most of us are aware that wattles and privet are allergenic, often causing acute hay fever and asthma. Olives are also a problem for many. But it was news to us that the worst offender of all is the silver birch.

Allergy to silver birch causes not only asthma and hay fever but predisposes the sufferer to food allergies and other health conditions (referred to as the oral allergy syndrome). Indeed people who show sensitivity to other trees are rarely without an allergy to birch pollen.

Scarily, there is evidence that exposure of infants to birch pollen predisposes them to subsequent allergies and pregnant women should also avoid exposure. Silver birches produce a vast amount of pollen.

This particular article, published in Landscape New Zealand, was written by Professor Spellerberg of Lincoln University. Such is his concern for the proven ill effects of birch pollen that he is sounding a loud warning at the use of these trees in public plantings. Being a graceful, quick growing tree, they are often used as a street tree. He is of the view that there are strong arguments for councils around the country to remove all existing silver birches in public places.

There is certainly food for thought there and anybody with predispositions to allergies might like to look into it further. Given the alarming growth of food allergies in children and our dreadfully high incidence of asthma in this country, I would be thinking twice about planting another silver birch near my house. It is such a shame I am looking a splendid specimen out my window. I will be watching out for further information on this topic.

Abbie and Mark Jury have a garden and nursery at Otaraoa Rd, Tikorangi.