Suppose you check some plants on the internet and found information- USDA plant hardiness zone 5-9. What would you understand by that?
While I was searching for information for ice plants, I found these lines on google. It is an interesting matter that scientists have divided plants and regions based on the tolerance of temperature and area. United States Department of Agriculture divided the USA into 26 parts based on the climatic condition. You will be clear if you see the figure below-
If you need an enlarged figure, click on the image.
This map was made based on average annual minimum winter temperatures. The range of temperature of each zone is kept between 10°F or 2.8°C. To be clear, suppose zone 1a has a minimum temperature of -60°F and a maximum -70°F or -51.1°C to -48°C. Likewise, the temperature gradually increases by 10°F (further subdivided by 5) or 5.5°C (further subdivided by 2.75). I want to show it as a table-
USDA zone Temperature in °F Temperature in °C Min Max Min Max
1a -60 -55 -51.1 -48.3
1b -55 -50 -48.3 -45.6
2a -50 -45 -45.6 -42.8
2b -45 -40 -42.8 -40
3a -40 -35 -40 -37.2
3b -35 -30 -37.2 -34.4
4a -30 -25 -34.4 -31.7
4b -25 -20 -31.7 -28.9
5a -20 -15 -28.9 -26.1
5b -15 -10 -26.1 -23.3
6a -10 -5 -23.3 -20.5
6b -5 0 -20.5 -17.8
7a 0 5 -17.8 -15
7b 5 10 -15 -12.2
8a 10 15 -12.2 -9.4
8b 15 20 -9.4 -6.7
9a 20 25 -6.7 -3.9
9b 25 30 -3.9 -1.1
10a 30 35 -1.1 1.7
10b 35 40 1.7 4.4
11a 40 45 4.4 7.2
11b 45 50 7.2 10
12a 50 55 10 12.8
12b 55 60 12.8 15.6
13a 60 65 15.6 18.3
13b 65 70 18.3 21.1
The hardiness zone indicates which plants can survive in the winter in which area. I found that the USDA zone mentioned on the ice plant is 5-9. That means the plant can tolerate -20°F to 30°F or -28.9°C to -1.1°C. If you see the map, You can find zone 5a is indicated with blue color, 5b- aqua, gradually color goes to light brown in 9b. So these zones are good to cultivate ice plants all year round. Because ice plants can tolerate up to -28°C in the winter.
But remember, this information is not absolute. It is just an example. It may vary from plant to plant or area to area. You may have your own country's hardiness zone or Agro-Ecological Zone. Before planting or choosing a plant, check your local information and decide wisely.
