Cacti are firmly affixed in legend, Movieland imagery and our imaginations as icons of desert life. Whether tall and commanding like saguaro (Carnegiea gigantea) and organ pipe (Stenocereus thurberi), diminutive like globe cactus (Mammillaria) and hedgehog (Echinocereus engelmannii) or shrubby like pricklypears (Opuntia) and chollas (Cylindropuntia), their sturdy, often spiny stems coupled with breathtaking blooms represent the twin nature of deserts and stark beauty united with severe living conditions.

Saguaro cactus

Saguaros are among the largest cacti.

Photo Credit: Gary Irish

Cholla cactus with red blooms

Some of the chollas have beautiful flowers.

Photo Credit: Gary Irish

Prickly Pear cactus

Prickly pears are among the most widely recognized members of the cactus family.

Photo Credit: Gary Irish

Cardon cactus

Cardon cactus is a huge, columnar species.

Photo Credit: Gary Irish

But these desert charmers are more diverse than simply tall saguaros gracing the Arizona sunset or little potted souvenirs. They offer an ease of care that make them enjoyable for all gardeners.

Most cacti are arid-land species, coming from areas that have intense sunlight and heat, long spells without rain and bleak-looking, often rocky soils. They dominate the succulent plant family and are splendidly adapted to meet the challenges of their harsh environment. These adaptations define the parameters of their care.

And it all begins with their remarkable roots.

All cacti have a wide, spreading root system of countless fine, webbed roots that are responsible for taking up water and moisture. These roots generally radiate far from the plant – in tall or columnar cacti, they spread at least as far as the height of the plant – but they remain as close to the surface as possible. In most species, roots rarely go below 6 inches from the surface, and even in huge, columnar species like saguaro, they’re rarely more than 3 or 4 feet deep.

The most remarkable – and important – aspect of cacti roots is how they adjust to soils that dry out. Once soil moisture reaches critically dry levels, the plant begins to shed its feeder roots. At that point, the plant undergoes a biochemical shift. It no longer relies on the moisture and nutrients brought up by the roots for photosynthesis. Instead, the plant reverts to drawing on its reserved moisture within its tissue. It can remain in this state for weeks, months or, in the case of massive plants, years. Once rainfall descends, the roots begin to regrow and reestablish their dominance as the main provider of water and nutrients. This remarkable turnaround occurs within a matter of days after a rainfall, and once re-formed, roots continue to perform this vital function until the soil dries out again.

These are root systems that have no mechanism for controlling water uptake; they’re either off or on and will continue to take up moisture until it’s either gone or the plant just erupts. It happens all the time – you’ve probably even seen it: Plants that are fat, bulging or have longitudinal splits – all of these are sure signs of too much water for too long a time.

When you’re in charge of giving your cactus water, it’s crucial to let the soil dry out completely between waterings. In a pot, regardless of the size, this means that the soil is dry throughout the entire volume of the pot before it’s necessary to water again.

In cool weather or when the plant isn’t actively growing, a cactus can go for weeks or months between watering. Never let the calendar be your guide – stick something in the pot, and when all signs point to “dry,” give the plant a long, good soak.

When your cactus is in the ground, the need to water depends on the soil and the weather. The ground holds more moisture for a longer period than a pot, so watch your plants. When it’s warm and it’s been a long time since the last rain, a good soak may be desirable. If you live in an area with more than 12 inches of a rain a year, you may never need to water a cactus in the ground. Remember, these plants are built for the dry, so always err on that dry side if you’re uncertain.

Whether you grow all your cacti in pots indoors and move your houseplants outside in summer or you have a yard full of cacti in all their wondrous forms, these amazing plants make a special addition to almost any garden. Accept their low level of care, and they’ll reward you with long lives graced each spring and summer by their spectacular blooms!