The vegetables that can be grown in an area depend on the climate in that area, and the concepts of gardening zone and micro-climates are helpful.
Gardening zones, also called hardiness zones, have similar climate conditions, help gardeners determine what plants will grow in each area, and are related to the annual extreme minimum temperatures.
There can be variations within each zone, and these variations are referred to as micro-climates.
However, hardiness zones have limitations. They say nothing about how long the growing season is in the area or how high temperatures may get.
For example, a plant could handle the low temperatures and the cold, but it still may not survive the summer heat.
Water availability also has an impact. Some vegetables can handle more summer heat if they have adequate water.
Peaks of mountains and valleys can have wildly different climates even though the hardiness zone is likely similar, as in my property in Simons Town.
Knowing when to start gardening can be tricky, even in a virtually frost-free area like Cape Town, which does occasionally have frost.
Many vegetables are sensitive to frost, so they must be planted after your last expected frost date or harvested before your first frost in the fall /
My garden behind my house is sheltered from the wind and thus has a different micro-climate from the area in front of my house.
Given its stable position, I have attempted to modify its climate, which I called a micro-ecosystem, and discussed its elements below.
The growing requirements needed for adequate plant growth:
- Readily adaptable conditions including growth media (both soil and soil-less) and water and nutrients.
- Less adaptable conditions include light and temperature and plants' and microorganisms' innate ability to adapt to environmental conditions.
The Micro-ecosystem section sets out to describe the specific biological, biochemical and physical growing requirements needed to grow high-quality organic vegetables and herbs in a small home garden.
Light and temperature can be modified to some degree; however, the extremes of temperature and deficiencies of spectral light energy requirements to grow plants cannot be adjusted sufficiently, except in specialised growing units.
The Micro-ecosystem section sets out the specific growing requirements needed to grow high-quality organic vegetables in my outside garden with its Mediterranean climate and winter rainfall similar to Northern California.