The Dog Tail Cactus (Strophocactus testudo, Selenicereus testudo or Deamia testudo) is sometimes confused with the Rat Tail Cactus (Aporocactus flagelliformis). Both have long, skinny, tail-like, trailing stems as they're establishing.
A polymorphic species, once the Dog Tail is mature, their stems broaden and change shape making it look considerably different from the younger plants. These cacti are also epiphytic (air plants). They have the ability to grow on the ground or on top of other plants. In their native jungle habitat, they can grow very large and are often found winding around trees.
Because of their long, trailing stems, cultivated Dog Tail Cacti make popular hanging basket and container plants. This cacti species can be grown outside, too, but they need the right amounts of sun, heat and humidity to thrive. For example, Florida is a state that they often do well in outdoors.
Dog Tail Cacti can produce large, fragrant white flowers. They're nocturnal bloomers, only appearing during the night. Don't be disappointed though if your plant doesn't ever bloom - unless the conditions are perfect, they rarely offer up any flowers.
|Botanical Name||Strophocactus testudo, Selenicereus testudo|
|Common Name||Dog Tail Cactus, Pitaya De Tortuga|
|Plant Type||Perennial succulent|
|Mature Size||Up to 3 meters|
|Sun Exposure||Full sun/ Partial shade|
|Soil Type||Tolerates a variety|
|Soil pH||Tolerates a variety|
|Hardiness Zones||7 to 11|
|Native Area||Tropical South America|
How to Grow Dog Tail Cacti
Like most cacti, your Dog Tail Cactus will prefer full sun if you're growing indoors or dappled, partial sun outside. They like heat, humidity, a fast-draining soil or potting mix, and more water than your average cactus.
Dog Tail Cacti are sun-loving plants. If they're grown in poor light conditions, the stems usually become etiolated. This means their stems will be too thin and their color and health won't be as it should be.
Good light also encourages healthy, short and sharp spines, rather than softer, hair-like ones.
For hanging baskets or containers, it's best to select a fast-draining and drying cactus mix. This will ensure your Dog Tail Cactus won't have problems with excessive moisture.
If you're making your own mix, using two parts of mineral such as sand, perlite, or fine gravel alongside one part of organic matter could work well.
If your cactus has to grow in overly wet soil, it will begin to rot.
Perhaps the trickiest part of caring for your Dog Tail Cactus is getting the balance right when it comes to watering.
Epiphytic cacti like more water than other cactus species, and will need more regular watering during the summer months. Making sure the soil or cactus mix dries out completely in between watering, however, is crucial—excessive watering results in root rot. If your cactus doesn't receive enough water, it can start to produce a disproportionate amount of less healthy aerial roots.
Temperature and Humidity
The Dog Tail is one of the more hardy cacti species. It can tolerate temperatures from around 40 degrees up to 90 degrees Fahrenheit. As you would expect, however, it can't tolerate frost. It's also a species that likes more humidity, rather than the dry heat that many cacti thrive in. In cooler regions, it really will only be suited to growing indoors.
Once your Dog Tail Cactus becomes root-bound and well established, it will benefit from regular feeding of diluted fertilizer during growth periods. Preferably it will be one specifically designed for cacti.
If you want to encourage it to flower, you could try providing a light application of a bloom booster fertilizer through the spring and summer. The bloom time is usually anytime from March to July. It's thought that they're also more likely to bloom if they have a few weeks of cooler nights.
Potting and Repotting
Repotting isn't essential with epiphytic cacti like this - they are relatively slow growing. However, if they're started in smaller pots and the roots are allowed to establish and fill the pot, if you then repot into a larger container, it will allow it to grow healthier, harder and larger spines as it matures. If it stays in a smaller pot, more aerial roots will likely form instead, and it won't necessarily be as healthy.
If you do repot, make sure the soil or cactus mix is completely dry first before carefully removing it. As you repot it, take care to spread out the roots and make sure you 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 go overboard with the amount of cactus mix or fast-draining potting medium that you use. These types of epiphytic plants thrive in just a little soil.
Propagating Dog Tail Cactus
Although Dog Tail Cactus can be grown from seed, it can be a challenge as cacti seedlings are usually very fragile. Instead, it's recommended to grow new specimens through propagation.
When healthy, they're prolific plants which have many stems, and they grow easily from cut or broken off pieces. Spring propagation is recommended.
Once you have selected the stem and cut it at the joint, its best to give the cut section a chance to fully dry out before replanting - this can take up to a week.
When you do pot it, make sure the mix used is fast draining and light and that it isn't overwatered. The soil should never be more than just a little damp at first to allow the roots to form. Once the roots are established, normal watering can begin.