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Plant Hardiness Zone Map


What’s a plant hardiness zone map?

A plant hardiness zone map is a geographical tool used to help gardeners, farmers, and horticulturists determine the suitability of various plant species for a particular region based on its climatic conditions. It divides different areas into zones based on the average annual minimum winter temperatures. These zones are numbered and colored, with each zone indicating a specific temperature range. You will find reference to these zones and maps in many books and videos you may watch so it is good to know what this means.

Gardeners and small farmers use plant hardiness zone maps to make informed decisions about which plants are likely to thrive in their specific climate and growing conditions. By selecting plants that are well-suited to their zone, they increase the chances of successful growth and productivity.

In the United States, the USDA (United States Department of Agriculture) has developed the most widely used plant hardiness zone map. It divides the country into several zones, ranging from Zone 1 (coldest) to Zone 13 (warmest), each representing a 12 degree Celsius difference average annual minimum temperatures.

Southern Africa’s climate and hardiness zones are similar to certain regions in the USA. For instance:

  1. Karoo (South Africa) and Arizona (USA): The Karoo’s semi-arid climate is comparable to parts of Arizona, particularly in the Sonoran Desert region. Both areas experience hot and dry conditions, and they share similar hardiness zones. Plants that can tolerate drought and extreme temperatures are suitable for both these zones.
  2. Cape Town (South Africa) and California (USA): The Mediterranean climates of Cape Town and certain parts of California align in terms of their temperature patterns. Both regions have mild, wet winters and dry, warm summers. The plant hardiness zones in these areas are often quite similar, allowing for the cultivation of plants that prefer Mediterranean-like conditions.
  3. Highveld (South Africa) and Midwest (USA): The Highveld’s moderate climate with cold winters and moderate summers can be likened to the Midwest region in the USA. Both areas have comparable hardiness zones, making it feasible to grow plants that thrive in temperate climates with distinct seasons.

It’s important to note that while there are similarities in hardiness zones, local variations in soil, rainfall, altitude, and microclimates can influence plant success. Gardeners and farmers should consider these factors alongside the hardiness zone map to make the most accurate planting choices.

h. Gardeners and farmers should always consider these factors in addition to the hardiness zones when selecting plants for their specific locations.

Namibias hardiness zones

Namibia does not have a plant hardiness zone map but we can use biomes and vegetation maps as a reference.

Here’s a list of Namibian plant growing regions based on their climatic characteristics, along with their correlations to the USDA and South African hardiness maps:

  1. Namib Desert and Coastal Regions:
    • Comparable to USDA Zone 10a (Southern California) and Zone 10b (Coastal Southern California).
    • Similar to parts of South Africa’s Western Cape Province (Cape Town and surrounding areas).
  2. Central Plateau and Highlands:
    • Comparable to USDA Zone 9b (Arizona) and Zone 9a (New Mexico).
    • Similar to South Africa’s Karoo region.
  3. Savannah Regions (Northern Namibia):
    • Comparable to USDA Zone 11b (Hawaii) and Zone 11a (Southern Florida).
    • Similar to some coastal areas of South Africa’s KwaZulu-Natal province.
  4. Eastern Woodlands and Zambezi Region:
    • Comparable to USDA Zone 11b (Hawaii) and Zone 11a (Southern Florida).
    • Similar to some coastal areas of South Africa’s KwaZulu-Natal province.
  5. Southern Deserts (Kalahari Desert and Southern Namib):
    • Comparable to USDA Zone 10a (Southern California) and Zone 9b (Arizona).
    • Similar to South Africa’s Western Cape Province (Cape Town and surrounding areas).

Please note that these classifications are meant to provide general correlations based on climate and growing conditions. Actual plant suitability can be influenced by factors such as soil type, altitude, water availability, and local microclimates. Always consider a variety of factors when planning your gardening or farming activities in Namibia.

South African hardiness zones

here’s a comprehensive list of the similar plant hardiness zones between Southern Africa and the USA:

  1. Zone 9b:
    • Karoo (South Africa) and Arizona (USA)
    • Both regions have hot and arid climates, suitable for drought-tolerant plants.
  2. Zone 10a:
    • Karoo (South Africa) and Southern California (USA)
    • Both areas experience mild, dry winters and warm, dry summers.
  3. Zone 10b:
    • Cape Town (South Africa) and Coastal Southern California (USA)
    • Mediterranean climates with mild, wet winters and dry, warm summers.
  4. Zone 11a:
    • Lowveld (South Africa) and Southern Florida (USA)
    • Both regions have warm, humid climates with mild winters.
  5. Zone 11b:
    • Coastal KwaZulu-Natal (South Africa) and Hawaii (USA)
    • Tropical climates with high humidity and warm temperatures year-round.
  6. Zone 12a:
    • Coastal Mozambique and Puerto Rico (USA)
    • Tropical climates with consistent warmth and high rainfall.
  7. Zone 12b:
    • Coastal areas of Eastern South Africa and Guam (USA)
    • Similar tropical climates with warm temperatures and high humidity.
  8. Zone 13a:
    • Extreme northern parts of KwaZulu-Natal (South Africa) and American Samoa (USA)
    • Warm, tropical climates with minimal temperature fluctuations.
  9. Zone 13b:
    • Tropical islands in the Indian Ocean (e.g., Seychelles, Mauritius) and U.S. territories like the Northern Mariana Islands
    • Warm, humid climates with steady temperatures.

It’s important to remember that while these comparisons provide a general idea of the similarities between regions, each area has its own unique microclimates, soil conditions, and local variations that can affect plant growth.

Another map of vegetation in Namibia:


Worthwhile links


Worthwhile videos

The intro is long so you might skip to minute 5 or so but a fun and worthwhile exploration of Namibia’s biomes and climates.

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