Tag Archive for: propagation

Why Do Cactus Have Spines ?

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spines of cactus

What comes to mind when you think of cactus?  

Perhaps the first thing you think of is the spines. If you have ever been unfortunate enough to have been pricked by a cactus, you’ll likely never forget that most of them have needles.  

*Did I ever tell you about the time I worked on golf course landscape and backed into a teddy bear cholla and got an entire piece lodged in the back of my leg?

Besides being painful to those who get too near to cacti, did you know that there are important reasons that cacti have spines?

spines of cactus

 Golden barrel cactuses (Echinocactus grusonii)

First, let’s look at the spines of cactus for what they are – the main part of cactus often functions as a modified stem, and its needles are the leaves.

The most obvious function of cactus spines is to protect the cacti from animals and people. There are, however, a few animals who aren’t deterred by the sharp spines of cacti such as javelina, tortoises and pack rats.

spines of cactus

 Saguaro cactus (Carnegiea gigantea) spines

Suprise, the primary function of the spines are to actually shade the cactus.

Although just one small spine would hardly provide shade, thousands of them can provide enough.

Why is sun protection needed for the surface of cacti? The shade from the spines let the cactus lose water through the atmosphere. This helps keep the cactus temperature relatively low.

spines of cactus

 Black-spine prickly pear (Opuntia macrocentra)

 Another function that the spines serve is that they help certain species of cacti such as cholla to root and spread.

spines of cactus

 Teddy bear cholla (Opuntia bigelovii)

Spines of the Cholla are specialized to detach and attach onto anything that comes to close. There are tiny barbs at the tips which grab on to anything that gets too close. It almost appears as if they ‘jump’ off of the main cactus as they latch on the unlucky recipient.

Spines of the Cholla are specialized to detach and attach onto anything that comes to close. There are tiny barbs at the tips which grab on to anything that gets too close. It almost appears as if they ‘jump’ off of the main cactus as they latch on the unlucky recipient.

**If like me, you are ever unlucky enough to find a piece of cholla embedded in your clothes or worse, your skin – you can use a comb to help pull out the barbs.  When hiking in the desert, it is easy to get them stuck on your shoes.  I usually grab a rock and use it to push off the Cholla segment.  When all else fails, a good pair of needle-nose pliers works.

young saguaro cactuses

 Two young saguaro cactuses are emerging from the shelter of a creosote shrub.

Hopefully, you have a new appreciation for cacti and their spines.  But, it’s still important to be careful because it hurts when you get pricked!

What Plant Where? Beautiful Plant Combinations

Purple, Prickly and Beautiful: Santa-rita Prickly Pear

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santa rita purple prickly cactus

Exploring the Beauty of Prickly Cactus

Do you like prickly cactus? I have a few favorites, one being the Santa-Rita Prickly Pear (Opuntia violaceae var. santa rita). The color contrast of their blue-grey pads and the shades of purple are so striking in the landscape.

The Santa-Rita Prickly Pear: A Stunning Accent Plant

The Santa-Rita prickly pear is a captivating addition to any landscape. Its blue-grey pads and vibrant shades of purple create a visually striking contrast. Not only is this cactus aesthetically pleasing, but both its pads and fruit are edible (though you may want to remove the spines first). Cold temperatures and drought conditions intensify the vivid purple color of this remarkable cactus.

Native Plant Beauty of the Southwest

Native to the Southwestern regions of North America, the Santa-Rita prickly pear can reach impressive dimensions, growing as large as 6 feet by 6 feet. However, if you prefer a smaller size, careful pruning at the junction where the pads connect can maintain a more manageable shape.

prickly cactus in full bloom

Blossoms and Wildlife with Prickly Cactus

In spring, the Santa-Rita prickly pear graces the landscape with lovely yellow flowers that later give way to red fruit during the summer months. Keep in mind that javelina, rabbits, and pack rats are occasional visitors that might nibble on the pads, while pack rats ingeniously use the pads to build their homes.

Handle with Care: Dealing with Spines and Glochids

Prickly pear pads are covered with clusters of 2″ spines and tiny spines known as glochids. Glochids are especially irritating to the skin and easily detach from the pad, making them challenging to remove. When handling these prickly cacti, use multiple layers of newspaper or a piece of carpet to protect your hands. Avoid gloves, as glochids can render them useless.

Removing Glochids Caused by Prickly Cactus

If you encounter glochids with prickly cactus, there are different methods to remove them, including applying Elmer’s glue, allowing it to dry, and then peeling off the glochids. However, many find greater success using duct tape for a more efficient removal process.

close up of prickly cactus

Versatile Uses in Landscaping

Beyond being a landscape accent, the Santa-Rita prickly pear serves as an excellent screen. Surprisingly, it can thrive in containers as well, although it’s essential to keep them away from high-traffic areas. These resilient cacti flourish in full sun or light shade and well-drained soil.

Low-Maintenance Prickly Cactus Beauty

Santa-Rita prickly pears are incredibly low-maintenance plants. When pruning, use tongs or newspaper to handle the trimmed pads. While they are highly drought-tolerant, occasional watering during the hot summer months, especially in the absence of rain, can enhance their appearance. Shriveled pads signal acute drought stress, so a little extra water can work wonders.

santa rita prickly cactus disease

Addressing the Cottony Mystery on Prickly Cactus

Some might mistake white, cotton-like areas on the pads as a fungal infection, but it’s actually caused by a small insect known as cochineal scale. Removing this cottony mass is simple—just spray it off with a strong jet of water from the hose.

pad cactus purchased at garden center

Propagation: A Simple Guide

You can propagate Santa-Rita prickly pear cacti with ease. Simply cut off a pad that is at least 6 inches tall, let it callus upright in a shady, dry spot for about two weeks, and then plant it with the cut end down.

Plant with the cut end down, do not water for the first month because the bottom is susceptible to fungal infections. After the first month, water every 2 – 3 weeks until established. 

Timing Matters

Planting in the summer requires shade until the cactus is established (approximately three months). However, it’s often advisable to wait until spring when the soil warms up for planting, especially in regions with cold winters.

Renewed Growth: Pruning and Propagation

For those with established Santa-Rita prickly pear cacti, you can rejuvenate growth by pruning or starting anew. Simply remove the cactus, cut off some pads, and replant them in the same location. Many have embraced this method and have been delighted with the results.

An Interesting Historical Fact

The Aztecs would cultivate prickly pear cactus infected with cochineal scale because the insects secrete a dark red dye with crushed. This was used to dye cloth. The Spanish exported this dye from Mexico back to Europe where it was used to dye royal garments and British military uniforms. The dye was highly valued by the Spanish, next to gold and silver. It takes 70,000 insects to produce 1 pound of dye.

*This is but one of many beautiful prickly pear species available to the home gardener. Do you have a favorite species of prickly pear cactus?