This week it seems timely to celebrate autumn and plan planting schemes for the winter. The summer recedes, but autumn can be one of the most beautiful and colourful seasons and the autumn leaf colours last an unusually long time in New Zealand especially in the north where leaf fall is not speeded by frost and gale.
As the prospect of Autumn appears and the rains return it is the ideal time to start thinking about planting trees, shrubs and many perennials. Late autumn and early winter is the optimum time to plant most trees and shrubs – better than spring in fact. It may seem a little odd to start planting just as we move back indoors for the cooler weather but if you plan and plant now the results next spring will be so much better.
This is because trees and shrubs planted now in the autumn will have ample chance to get their root systems well established during the milder, moist weather over the winter and, once the spring comes will grow so much faster (having a bigger root system established in the soil). They will also be far better able cope with any periods of drought during the following summer. I also believe that the approach of winter is a natural opportunity to think about planning because growth is slow and there are less demands on our time for maintenance. In the north of New Zealand, autumn and spring are the main growing and flowering periods. Many bulbs flower in autumn (Nerine, cylamen, autumn crocus, for example), some perennials flower again following a summer rest and even some shrubs such as camellia. The combination of flower and autumn leaf colour is characteristic of the autumn and make it a very attractive season.
Coming from the UK ten years ago it was a great surprise to me to see such colour and life in the gardens in the autumn and early winter – it reminded me of an English spring, and a bit of a Mediterranean winter. In fact the winters in Northern New Zealand are very like a Mediterranean winter and hence the many similar ornamentals that are happy here (citrus, olive, hibiscus, bougainvillea, cypress and so on).
So, to thinking about planning the planting to be carried out this winter and enjoyed next summer. In my last article I wrote about inspiration for planting design and using form, colour and other qualities of plants. I will continue with some tips on another vital aspect of planting design, one that is related to the plants form-canopy layers – what? you may ask. Now all plants whether herbaceous, shrubs or trees make a foliage canopy. For trees it is high up, for shrubs, lower, and for perennials, ferns, and bulbs, generally lower again. Now this means that at least three types of plant can grow in the same area by occupying different levels above the ground. This is a common arrangement in nature, for example in the forest and in shrubby areas and even in tussock grassland or salt marsh where small plants creep in underneath the taller ones.
Two salt marsh natives demonstrate how plants live closely together at different levels- Selliera radicans forms ground cover below sea rush.
This provides a model for the garden. One of the best way of combining plants is to grow one kind above and below another. So we can make a woodland garden below mature trees, bulbs below the canopy of spreading shrubs and ground cobver underneath seasonal bulbs. The seasonal aspect is important. For example bulbs that die down during part of the year can be grown among evergreen plants or to rise up through evergreen ground cover. An example of this is the combination of dwarf agapanthus with bulbs such as kaffir lily. You can aim for simultaneous flowering or staggered flowering.
There is one more thing about this kind of planting. To be aesthetically successful you must use generous masses of each plant (see the example of the woodland ground cover in the photo below). In this way you get variety by planting in vertical and seasonal ‘layers’ rather than by crowding many varieties next to the other. This means planting in tens or even hundreds of smaller plants rather than one two or three of each. But it gives a strong confident look to the planting design and can give plenty of variety through the seasons as well at any one time.
This photo of a Oehme and van Sweden garden in the USA shows classic canopy layers in a deciduous woodland garden – trees, occasional shrubs and dense ground layer planting of woodland perennials