First developed by the United States Department of Agriculture (USDA), the hardiness zone is a geographically defined area in which a specific category of plant is capable of growing. It takes in consideration climatic conditions, including its ability to withstand the minimum temperatures of the zone as seen in the graphic below:
For example, a plant that is described as “hardy to zone 8” means that the plant can withstand a minimum temperature of −12.2 °C (10 °F). A more resilient plant that is “hardy to zone 7” can tolerate a minimum temperature of −17.8 °C (0 °F).
Today, the use of the hardiness zones has been adopted by many countries, but only a few have the specific details about their scale.
According to the website The Spruce, the following map of Africa’s Hardiness Zones shows higher zones than the accepted USDA map allows for. Since there isn’t yet a more specific study and analysis of Egypt’s zones, it’s not sure if the country is in Zone 10 or 11, since there are different results in different websites.
According to the map above, Egypt would be in the Zone 10, which means that the plants can withstand a minimum temperature of −1.1 °C (30 °F).
We know for a fact that the natural vegetation of Egypt is varied. Some sources of water exist in the Western Desert and you can also find the growth of perennials and grasses in this area. The coastal strip has a rich plant life in spring. The Eastern Desert receives sparse rainfall, but it supports a varied vegetation that includes temarisk, acacia and markh, also a great variety of thorny shrubs, small succulents and aromatic herbs.
Despite the informative value of the hardiness zones, these studies cannot be used without supplementary information, specially because of the lack of details and specificities that should be considered for growers and planters in every part of the world.