Well, I am not 100% sure on this but it's what I'm assuming. I mostly think it is because they grow in very, very hot countries that only has rain every now and again. If you look at other plants that have an equal amount of sun and rain they grow faster. However, cactus' don't. They are specifically built to survive in very hot conditions that barely has any rain. Therefore, cactus' don't have as much rain to grow faster.
Cactus are a desert plant, and so need to send their roots deep down for their food.
Cactus grow very slow because it is saving water for the later time. Cactus grow in the desert, and it merely rains in deserts. So, when it does rain, the cactus takes up as much as water as it can and saves it for the rest of the period of time until it rains again, which is why they grow slowly. They use small amounts of water for itself everyday, which makes it grow slower.
I think a cactus can grow in soil. I think a cactus can grow in soil.
If you want flowers to grow on your cactus you are supposed to water your cactus.
You put the cactus on sand. There is no seed required. Also know they cannot grow right next to each other.
Yes you can grow cactus in mine craft Pocket edition ,cuz I have a cactus farm
they grow faster than hardwoods really!!
Because a cactus can't grow in clayey soil and there is a lot of water in the marshes, the cactus does not need a lot of water
Dessert
cactus
Dessert
They are actually called 'Cactus Flowers'