Succulent plants have large cell walls capable of storing water over long periods of time that give them their distinctive, fleshy appearance. Succulent leaves and stems are generally swollen and thick, and may contain different coverings around their foliage, depending on the species.
Although many people assume all succulents are cacti, only succulents in the Cactaceae family are true cactus plants. Most succulents are indigenous to arid or semi-arid desert climates, where extreme environmental fluctuations are the norm.
Succulent plants developed their unique appearance through evolutionary survival in harsh conditions. Succulents are able to take advantage of quick, infrequent precipitation cycles due to their ability to hold and store water.
Succulents can conduct large volumes of water and are able to ration this supply over long drought periods, with reduced rates of photosynthesis and subsequent cellular respiration and transpiration. This is why vigorous growth is a trait that is almost entirely absent from most succulent species.
The puffy, swollen leaves and stems of succulent plants are a result of their thick xylems—the vascular tissues responsible for conducting water to all cells in the plant during regular cycles of photosynthesis and evapotranspiration.
Some succulents are able to close, or partially close, their stomata during the hottest, driest times of day to avoid excessive transpiration and water loss. Impressively, these plants are able to take up and store carbon dioxide at night, when risk of water loss is not as eminent.
The carbon dioxide is then slowly converted into glucose to be used selectively during the day. Many succulents in the Crassulaceae family carry this genetic trait, which is why it’s known as the crassulacean acid metabolism (CAM).
Some succulent species also have unique foliage coverings or materials that help protect them from harsh wind, low humidity and sweltering heat. An example of such a material is the thick, waxy coating on the cuticle, which adds protection from heat and wind.
Another interesting example is the “hairy old man” cactus Cephalocereus senilis, which develops a thick, white, hairy substance around the plant’s needles. Some of these features also help deter pests. Succulents commonly possess small leaves, which reinforce their water-holding traits, and most succulent stems also help the plant store chloroplasts for food.
Steps for Cloning Succulents
Most succulents are slow to germinate from seed and require a high degree of both patience and effort. Asexual propagation, or cloning, offers gardeners an easy solution that does not require much specialized equipment. For general propagation, these tools, materials and environment are required:
- Planting medium
- Mother plant
- 3-4-in. breathable pots
- Razor blade or sharp scissors
- Propagation tray or any clean surface
- Low-humidity environment with ample warmth and filtered sunlight, or partial exposure to HID or low-wattage LED and T5 fluorescents
- Air movement to help replicate natural climate conditions
Some succulent species require specialized procedures for propagating, so always research the exact species you intend to work with. Most species respond favorably to the general approach outlined here. Individual leaves and whole stem cuttings taken from a mother plant can both be used. If your plant has excessively fat leaves, which hide the majority of the stem, it is best to work with individual leaves.
Select a stem or leaf somewhere around the middle of your plant. If you are making a stem cutting, allow a minimum of three nodes, and no more than six nodes, per clone. When making the cut, always use a sterile pair of scissors or razor blade.
Making a choppy cut on a succulent is a great way to invite the presence of fungal spores and diseases. Ensure you leave no stubs on your mother plant after making cuttings (a part of the plant’s stem with no active growing node). These stubs are likely to rot, which can endanger your mother plant.
A lot of plant propagators treat their cuttings with a variety of vitamins and plant growth regulators like IBA, but this is far from the case with succulents.
Succulent cuttings need time to use up their hefty element and water stores before planting, and must be left out to literally dry up before they are given a new home. Leave your cuttings unplanted in a warm, dry environment with some filtered light for at least a couple of days.
After three or more days, you will notice the cutting’s cuticle has sealed and a scab is present. The cutting is signaling that its food and water reserve is starting to dwindle and it could use a new home. Once your cutting has dried up, it is safe to plant it.
It is important to keep track of which side is up when taking cuttings, as succulents will not grow upside down. Draw an arrow on your tray and align the cuttings to follow the arrow, allowing for easy identification when it comes time to plant.
When planting, insert the minimum surface area of stem or leaf into the growing media. As long as some contact is made, roots will eventually form.
Forcing cuttings too deep, or even as deep as what is normal for other cuttings like tomatoes or basil, will undoubtedly cause root rot, botrytis or both. At this point, the medium should be evenly watered.
Choosing the Best Grow Media for Succulents
There are many commercial cacti and succulent mixes out there. Many of them contain chemical fertilizers that, in the case of succulents, could do more harm than good and may not be ideal for your specific species, as many of these mixes also contain excessively high amounts of peat, which may provide an environment that’s too acidic for some species.
Too much peat in a succulent mix may also hold too much water at once, then when it is left to dry it may become extremely hydrophobic, preventing proper aeration, circulation and percolation of water to the succulents.
I suggest making your own succulent media blend, taking inspiration from their natural environments. Good components of a succulent mix include sand, perlite, vermiculite, gravel and crushed stone or clay.
Many growers claim to be successful with coconut coir, but it should be used carefully. Many succulents also grow in limestone, which is a suitable media, but be sure to buffer its pH, or select basic, tolerant succulents to grow in the limestone. With percentages based on volume, an example of a good succulent mix includes:
- 35% clean, untreated sand. Avoid construction sand and aim to purchase sand from your local garden supply or hydroponics store.
- 25% perlite
- 15% vermiculite
- 15% pebbled expanded clay or crushed gravel
- 10% peat or coco coir
Aim for a medium that has a high micro- and macro-porosity and the ability to drain easily. It is also helpful to use clay or breathable fabric pots, or some other permeable vessel that does not restrict airflow. Plant your cuttings in shallow pots and do not race to increase your pot size too soon.
Succulents have adapted to grow shallow, wide roots to make use of quick, infrequent watering. The easiest way to kill a succulent is to give it too much space.
Once your cutting is in its new home, do not water it again until the media is completely dry and the plant has started to show slight signs of wilting.
Once you provide the first true watering, the leaves and stems will swell. Keep your new plants away from excessive humidity and intense sunlight for the first couple of weeks.
Within a month, you will see some air roots poking out of the place you made the original cut, and in some cases, new miniature leaves developing off the tip of the older leaves without stems. Eventually, the newly formed roots will poke their way into the media and a new plant will emerge.