How to Grow and Care for the Dog Tail Cactus

A large, mature Dog Tail Cactus winding around a tree

Wendy Cutler / Flickr / Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0)

The dog tail cactus (Strophocactus testudo) bears broad main stems with long, skinny tail-like trailing stems as they are established. These cacti are epiphytic (air plants) and can grow on the ground or atop other plants. In their native jungle habitat, they can grow up to 9 feet tall and are often found winding around trees. Because of their long, trailing stems, cultivated dog tail cacti make popular hanging basket and container plants. When properly cared for, your dog tail cactus will produce white, fragrant flowers nocturnally. 

Common Name Dog Tail Cactus, Pitaya De Tortuga
Botanical Name Strophocactus testudo, Selenicereus testudo
Family Cactaceae
Plant Type Perennial succulent
Mature Size 10 ft.
Sun Exposure Full sun, partial sun
Soil Type Sandy, rocky, well-drained
Soil pH Neutral, acidic, alkaline
Bloom Time Summer
Flower Color White
Hardiness Zones 7-11 (USDA)
Native Area South America
Example of the flower on the Dog Tail Cactus
It can be tricky to get Dog Tail Cactus to flower. When they do, it's overnight, and they produce large, fragrant white blooms Ulf Eliasson / Wikimedia Commons / Creative Commons Attribution-Share Alike 2.5 Generic license

Dog Tail Cactus Care

Like most cacti, dog tail cacti prefer full sun. They grow best in heat, humidity, fast-draining soil, or potting mix. They require more water than your average cactus but may develop problems like weak stems or root rot if they receive too much. Pruning a dog tail cactus isn't essential unless you notice dead or diseased parts of the stem, in which case you may prune carefully.

Propagating a dog tail cactus with seeds is difficult but can easily be done using root division or cuttings. While dog tail cacti are hardy, they can become damaged by dampness or frost from harsh winter weather. It's best to overwinter a dog tail cactus indoors with ample sunlight.

Light

Dog tail cacti grow best in full sun. Its stems usually become too thin and dull in color if grown in poor light conditions. Ample sunlight also encourages healthy, short, and sharp spines rather than softer, hair-like ones.

Soil

Growing dog tail cacti in a fast-draining and drying cactus mix is best. This will ensure your cactus won't suffer issues from excessive moisture. If your cactus has to grow in overly wet soil, it will begin to rot. When making a soil mix from scratch, use two parts mineral, such as sand, perlite, or fine gravel, mixed with one part organic matter.

Water

Epiphytic cacti require more water than other cactus species and will need more regular moisture during summer. However, ensuring the soil or cactus mix dries out completely in between watering is crucial. You must provide your dog tail cactus with the correct water balance and dryness. If your cactus doesn't receive enough water, it can start to produce a disproportionate amount of unhealthy aerial roots.

Temperature and Humidity

The dog tail cactus is among the hardier cacti species. It can tolerate temperatures from around 40˚F up to 90˚F. However, it can't tolerate frost. The dog tail cactus prefers humidity over the dry heat that many other cacti thrive in. In cooler regions, the cactus is better suited to indoor growth.

Fertilizer

Once your dog tail cactus becomes root-bound and well established, it will benefit from regular diluted fertilizer feeding during growth periods. Ideally, the fertilizer is formulated specially for cacti. You may also provide a light layer of a bloom booster fertilizer through the spring and summer.

Types of Dog Tail Cacti

  • Strophocactus brasiliensis
  • Strophocactus wittii 
  • Strophocactus sicariguensis

Pruning

You don't need to prune a dog tail cactus unless you notice that its leaves have died, become damaged, or it has grown a limb so large that it may tip over the plant. Very carefully remove limbs at their branch point without cutting into the cactus's main stem. You may use pruners or your fingers to snap off dead sections of the plant.

Propagating Dog Tail Cacti

Healthy dog tail cacti bear many stems and can grow quickly from a cut or broken-off piece. It's best two propagate in the spring. Here are two propagation methods:

To propagate with cuttings:

  1. Choose a stem and let it dry fully before cutting it at the joint.
  2. Allow the cutting to form a callus.
  3. Wait three to four days before planting the cutting in a potting mix.
  4. Mist the mix and wait for roots to develop before relocating.
  5. Once roots are established, you can water normally.

To propagate with root division:

  1. Root a stem from your cactus.
  2. Bury a part of the stem in rooting soil or potting mix.
  3. Mist the stem every three to four days.
  4. Wait about three weeks for new roots to develop.
  5. Remove the stem from the mother Dog Tail cactus.

How to Grow Dog Tail Cacti From Seed

Although dog tail cacti can be grown from seed, it can be challenging as cacti seedlings are usually very fragile. If your cactus pollinates well after bloom, it will produce seeds from which you can propagate the plant. With the arrival of spring, plant the seeds in a pot filled with potting mix and apply a thin layer of sand. Allow the seeds to dry completely before storing them in a dry, dark location. Continue to mist the seeds through germination; once established, water normally.

Potting and Repotting Dog Tail Cacti

When repotting a dog tail cactus, ensure the soil or cactus mix is completely dry before carefully removing it. When you re-pot it, select a well-draining pot, and spread out the roots. Leave the plant dry for at least a week before initial light waterings. This will reduce the risk of any root rot occurring. Don't over-apply cactus mix or fast-draining potting medium, as these cacti thrive in little soil.

Overwintering

It's best to overwinter dog tail cacti indoors, particularly in an unheated garage near a window or grow lights. While cacti can withstand cold temperatures, they will suffer from wet soil caused by snow or frost. Epiphytic cacti, such as dog tail cacti, are slightly more sensitive to winter weather and low temperatures, so make indoor overwintering a priority.

How to Get Dog Tail Cacti to Bloom

The bloom time for a dog tail cactus is usually between March to July. Once in bloom, they produce large, fragrant white (or sometimes pink) flowers that resemble orchids. Dog tail cacti are nocturnal bloomers, meaning the flower opens late in the day and stays open during the night. Don't be disappointed if your plant never blooms. Unless growing conditions are perfect, they rarely offer up any flowers.

Common Problems With Dog Tail Cacti

Problems with dog tail cacti usually arise from overwatering, under-watering, or insufficient light.

Discoloration on Stems

Discoloration on dog tail cactus stems is likely a result of poor watering practices. If your cactus is receiving too much or too little water, its stems will become pale. This may also result from frost damage, mold, or lack of sunlight. Consider moving your cactus in addition to adjusting its watering routine.

Weak Stems

If the stem of your dog tail cactus seems weak, you likely need to increase its exposure to light. The plant doesn't require direct sunlight, but ensure it at least gets a boost of indirect light, either indoors or shaded by other plants. Dark tips may accompany weak stems.

FAQ
  • What is the difference between the dog tail cactus and the rat tail cactus?

    Rat tail cacti (Aporocactus flagelliformis) are similar to the dog tail cactus but are slightly smaller, bloom between late spring and early summer, and produce orange or pink flowers. The dog tail cactus requires more water than the rat tail cactus.

  • How long does the dog tail cacti live?

    In the wild, dog tail cacti can live for centuries. However, if you grow the plant indoors, it may only live up to 10 years.

  • Are there downsides to owning a cactus?

    Cacti make for great plants, indoors or outdoors, however, if you have children in your home, the sharp stems may pose a risk for injury.