Cacti are some of the most durable and versatile plants on earth. Their natural success in the extreme conditions of dry deserts and rocky steppes make them a reliable addition to your landscape and a great choice for conserving water. The real secret of a cactus’ success is its fleshy stem and root tissues that can store water for long periods of time. Because they can tolerate dry conditions, cacti are perfect for sunny spaces that are difficult to reach with water. Individual potted plants make nice centerpieces on patio or end tables. Planters filled with cacti can also be placed in the landscape to add height and interest.
Bonus: It should come as no surprise that cacti with long spines are usually uninviting
While succulent plants have origins throughout the world, cacti are native only to North and South America. The majority are found in desert regions where the winter temperatures remain above freezing, however, there are several types of cacti that are winter hardy. That means even if you don’t live in a desert region, you can still include cacti in your landscape design. Of course, any potted cactus can be grown outdoors through the summer and taken indoors for the winter.
Choosing the Right Container
When it comes to containers, all the same rules apply to growing potted cacti outdoors, as they do for growing them as houseplants. Whatever container you choose needs to have good drainage. If there are no holes in the base of the container then you will need to drill a drainage hole in the base (multiple holes if the container is large). Unglazed terracotta planters are especially good for cacti because of the porous nature of fired clay. Moisture can permeate the pot and evaporate away; reducing the risk of overwatering your cactus.
How to Care for Your Cactus
Whether you are planting your cacti in the ground or in containers, you will need to provide them with four basic requirements to keep them at their best.
In general, a cactus needs 6 or more hours of direct sunlight. Most can handle full sun all day long, however there are a handful that have more sensitive “skin”. In nature they grow in the shadow of taller plants or rocks that provide shade during part of the day. Cacti can show symptoms of sunburn during long periods of high heat (over 90°F) and humidity. If you notice that your potted cactus plant is getting sunburned (spots developing or a bleached-out look to the plant), move it where it will still receive 6 hours of direct light (preferably in the morning to early afternoon) but shade for the rest of the day. Plants in the ground might have to be lifted and moved, or if it suits the layout of your landscape, you could install a decorative screen, lattice, tall plant, or a shrub to create shade from the afternoon sun.
It’s best to water cacti at the soil surface. If you are watering plants from overhead, using a hose or watering can, try to water early in the day so that the plant has time to dry well before the cooler evening temperatures set in. Water sitting in the tight nooks found on the surface of many cactus plants can create a perfect climate for rot to develop.
You may need to water containers more frequently during hot, sunny weather. Water less during rainy periods or during a long stretch of overcast skies. Feel the soil to check for moisture. If the top two inches of soil are dry, then it’s time to water.
Cacti can be grown in raised beds or large containers in areas where the soil is high in moisture or clay. Just make sure to fill the bed with a soil mix recommended for cacti.
If you are planting directly into the ground and your soil isn’t already a mix of organic and gritty materials, then you may need to amend it. Try to create a mix of half to two-thirds soil and the remainder some type of gritty material that will enhance good drainage. Things like fine grade pumice, crushed gravel, or pea gravel are good choices. Mix the soil to a depth of six to eight inches.
The easiest way to ensure that your outdoor potted cacti have the right kind of soil is to purchase a potting mix specifically formulated for cacti and succulents. If you want to mix your own, a 1:1 blend of potting soil and perlite will do the job. Crushed pumice or gravel can be used instead of perlite, but perlite is lightest in weight. In case you want to move your containers around, a light-weight soil will make it easier. Pure sand is not a good potting medium. It doesn’t provide any nutrition to the plant, it’s heavy, and sand can become so compacted over time that it blocks water drainage.
Many cactus plants won’t survive the winter in areas where the temperatures reach freezing or below. In those areas you can grow tender cacti as annuals in the garden or in containers. Cacti grown in containers can be brought indoors for the winter and returned outside the following spring.
What’s the Difference Between a Cactus and a Succulent?
Both cacti and succulents can store water within their tissue, and both are native to arid climates. Their main difference is a special structure found on cacti called an areole. Areoles are small round spots found on every cactus that produce tufts of small hairs and/or spines. While there are a few types of succulents that produce thorns, the thorns don’t emerge from areoles, and so they are not cacti.
Looking for other plants that would make good companions to your cactus? Click here for a list of drought-tolerant plants.