5 Fascinating Things You Didn’t Know About Cacti

updated Jul 18, 2020
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(Image credit: Marisa Vitale)

Cacti are weird plants when you stop to think about it. They don’t look particularly lush, like most other houseplants, and their stark appearance makes them feel a bit alien. In fact, they’ve been residents of planet earth for 35 to 40 million years, far longer than humans, and they’re a fascinating species. Here are five cool cacti facts that will make you look super knowledgeable when you tell your friends.

(Image credit: Marisa Vitale)

They Vary Vastly

You’d be forgiven for thinking cacti are all basically similar—every variety looks sort of bald and prickly. But there’s actually huge variety in this plant family when it comes down to it. In fact, they can range from one inch to 65 feet in height. Mexican giant cardon (Pachycereus pringlei) is the tallest cactus in the world, while saguaro is the largest variety in the United States (Carnegiea gigantea).

They Grow SO Slowly

Cacti can live for decades as houseplants, and hundreds of years in the wild, and they grow at an excruciatingly slow rate. It takes 10 years for the massive saguaro cacti to reach one inch tall, according to the National Park Service, and they won’t reach their full height of 45 or more feet for 200 years. Saguaros develop flowers for the first time at the pubescent age of 70.

(Image credit: Samara Vise)

They Have Unexpectedly Pretty Flowers

It turns out that all species of cacti grow flowers, though they’re rarely seen in some varieties. To encourage your cactus to flower (assuming it is mature enough—some won’t be ready for decades), allow it to go dormant during winter. Stop feeding it, cut back watering to once a month or less, and keep it in a bright but cool area (about 50-55 degrees).

(Image credit: Marisa Vitale)

They’re Survivors

Anyone can grow a cactus. They’ll survive just about any abuse you throw at them, short of overwatering (and some can even be revived after several months of not watering them at all). And you can grow them just about anywhere—pots, trays, window boxes, in the ground—just as long as they aren’t exposed to freezing temperatures.

(Image credit: Samara Vise)

Their Needles Are an Evolutionary Necessity

Cacti evolved their prickly needles, spines, and thorns to keep desert-dwelling animals and people from eating them into extinction. When food and water are scarce, a big green cactus looks awfully tempting… until you try to touch it.

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