A frequently asked question in Positive Cycle Training Company Workshops is 'when can we plant what'. Its a simple enough question, with a somewhat complex answer. While it is very true to say that during August we plant, for example, bush and climbing beans, beetroot, brinjal and carrot as well as strawberries, turnips, sweet peppers and of course tomatoes it is also true that some of these will struggle in certain parts of the country during August. Experienced growers develop a sense for what is going to work in their region and even within their own micro climate. An extreme example would be the difference between Sutherland (the coldest region in the country) and Northern Kwa Zulu Natal. Obviously we could expect tomatoes to thrive in the warm spring of the near tropical north of South Africa while they would almost certainly not survive the still freezing mountainous conditions of Sutherland.
A more subtle climatic variation though, would be the two degree difference in average temperature between the Johannesburg area and those farms found immediately north of Pretoria. The slightly warmer conditions north of the Witwatersrand watershed would allow for earlier planting of tomatoes than the micro climates found nearer to Johannesburg's peri urban areas.
So local experience, and of course planting on slopes that face the right direction, make a difference to all crop planting and harvest times.
Now here is where things get a little more interesting. Given the need to save seeds and sow them year upon year, we can reasonably conclude that seeds grown successfully within a particular micro climate will be 'hardened' or adapted to that particular set of climatic conditions. Meaning that if we were to harvest seed from the areas north of Pretoria after many successive generations and plant them South of the Rand, they may well fail since those seeds would not be adapted or ' naturally selected' to survive the slightly colder conditions.
So we see that planting seeds suitable to a particular area, as well as in the right time frame for the climatic conditions found in that area is necessary in order to facilitate successful organic crop performance.
Not only that, but we have to consider not just the timing, but the actual conditions being experienced in each particular micro climate. So it is not simply a matter of looking up what to plant on a calendar, but rather to be aware of what temperature, moisture and light ranges each particular crop or variety of crop needs in order to grow successfully.