The previous topic that we discussed (‘Soil is WHAT?”) introduced the concept of “Right plant, Right place.”
Since soil is the most difficult to manipulate of all ecosystem parameters required for optimum plant growth, we deliberately identified this topic as the point of departure.
It was also crucial to highlight the concept that soil is an ecosystem in its own right and must be treated as such.
But what else is crucial if we want optimum plant growth with minimum maintenance? The ideal would be to observe the plant considered for the garden in its natural habitat (to observe its natural growing conditions) prior to planting it in our own gardens. Unfortunately, that is not always possible. Many of the plants available today actually belong in zoos because they will never survive on their own – requiring TLC for the rest of their lives.
Let us look at the three other most crucial aspects that you must consider when you decide to make your garden a part of the local regional plant community. These variables are: Temperature, Aspect, and Rainfall. Quite often all these parameters are grouped under one term, namely Habitat.
Where most of us fail spectacularly, is the importance of temperature and its variability over the season. For the most part of the year, the temperatures on the Highveld are quite pleasant. In fact, over the last few years, frost was rather uncommon in many areas. That is precisely where we go wrong. Plant selection should be based on the coldest temperature that might occur in your garden (or specific habitat in your garden). Only one night of severe frost is required to wipe out a garden. However, it is true that certain plants become hardier with age. Personally, I will only take this gamble once my garden has developed some nice protected spots.
In the picture above, vegetation is influenced by a few variables, amongst them temperature. Plant density is much higher near rock outcrops where the temperatures do not drop so significantly during the night. The really exposed areas only show grass cover. (However, the denser vegetation along the stream is water related).
Aspect simply refers to the amount of sunshine that a plant receives (and it is often linked to temperature as well). “Position” is actually a better word to use, but “Aspect” is the one you will find in the literature.
I trust that most of us are familiar with the Magaliesberg.
The gentle, northern slopes receive ample sunshine and the vegetation is totally different to that of the steep, southern slopes, even if one compares plants in similar soil types. The Magaliesberg is also intersected by deep ravines, or kloofs, where the plants also differ significantly from the other two sites. In the case of ravines, other parameters also apply – for instance, very rich soil type and constant water availability, but the point is that aspect matters. In a garden aspect is often artificially created by either artificial walls or tall trees.
The most challenging of variables to manage is most probably rainfall. In our neck of the woods, the term “average rainfall” is a mathematical concept. In practice, we either have too much or too little rain and quite often at the wrong time. So how do plants in the wild survive then? The answer is quite simple: “RIGHT PLANT, RIGHT PLACE”.
The picture above is of a small doline (sinkhole) in the dolomites. During a rainstorm excess surface water flows into the doline, increasing the “effective” rainfall of this area. This process also leads to deeper weathering of the soil, holding even more moisture. The bottom line? If you want to see unusual plants on the dolomites search for a doline.
We can apply the same principle in our gardens to increase the retention of rainwater on site.
It is really becoming imperative that you study plant requirements before you purchase plants for your site. Do not be tempted to buy the plant that has a lovely flower at the time you visit the nursery. Talk to the staff at the nursery about your requirements or search the www for information. Within the next few years, a garden will become a luxury that few people can afford, unless you start planning now. It will require a paradigm shift in thinking and that takes time (and guts) but if you don’t, you will feel it in your pocket. The Capetonians have already been (rudely) sensitised to the fact that a garden is a luxury you can do without- unless you plan properly and redefine the concept of “Garden”.
In the next issue, I want to discuss the dynamic nature of a garden that has incorporated ecological principles in its design. The focus remain on grasslands and plant palettes that could be incorporated in Highveld gardens.
If you want to share any ideas/practical experiences with me please send me an email at: [email protected].