String of pearls plants are unique vining succulents that are easily recognizable by their tiny pea-shaped leaves. The leaves grow on trailing stems that gracefully spill over the sides of planters and hanging baskets much like the string of rubies succulent. The plant is a robust and quick grower—gaining about five to 15 inches per year—but does not live long without propagation. Thankfully it is easy to propagate the plant using its stems.
I. Appearance and Characteristics
Curio rowleyanus, syn. Senecio rowleyanus, is a flowering plant in the daisy family Asteraceae. It is a creeping, perennial, succulent vine native to the Cape Provinces of South Africa. In its natural environment its stems trail on the ground, rooting where they touch and form dense mats. It often avoids direct sunlight by growing in the shade of other plants and rocks. It is commonly known as string-of-pearls or string-of-beads.
“String-of-beads” and several other common names are shared with Curio herreanus (string of watermelons), which has teardrop-shaped leaves, rather than spherical.
This plant was named after British botanist Gordon Douglas Rowley who specialized in Cactaceae and succulents.
Curio rowleyanus receives its common name from specialized leaves which are the size and shape of small peas (about 6 mm or 1⁄4 inch diameter).Its trailing stems can grow 2–3 feet (60–90 cm). There is a small tip at the distal point of each leaf and a thin band of dark green tissue on the side known as a “window” (see below). It blooms during the summer and, like all asterids, it has a compound flower. The trumpet shaped flower forms clusters (about 13mm or 1⁄2 inch diameter) of small white flowers with colorful stamens. The flower will last about a month and is said to smell like cinnamon and other spices.
Leaf morphology
The odd shape of the leaves is an adaptation to arid environments and allows for the storage of water while exposing a minimum amount of surface area per volume to the dry desert air. This greatly reduces water loss due to evaporation relative to the typical dorsi-ventrally flattened leaves of most angiosperms. Although its spherical leaf morphology contributes to minimizing water loss, it also dramatically reduces the surface area available for the absorption of light and photosynthesis.
An adaptation that may help compensate for this reduction in light interception is a narrow, translucent, crescent-shaped band of tissue on the adaxial side of the lamina. This specialized structure is known as an “epidermal window” and it allows light to enter and irradiate the interior of the leaf, effectively increasing the area of leaf tissue available for photosynthesis. This is a trait shared with Curio radicans (string of bananas), a close relative of Curio rowleyanus. A similar morphology is observed in species of the genus Fenestraria as well as the species Haworthia cooperi and Frithia pulchra, which grow underground and only expose their leaf tips to absorb light radiation.
The vegetation of C. rowleyanus is somewhat poisonous and should not be consumed. In humans the string of pearls plant is rated as toxicity classes 2 and 4 by the University of California, Davis. Class 2 is defined by minor toxicity; ingestion of string of pearls may cause minor illnesses such as vomiting or diarrhea. Class 4 is defined by dermatitis; contact with the plant’s sap may cause skin irritation or rash. Likewise, if consumed by animals it can cause vomiting, diarrhea, drooling, skin irritation or lethargy.
Like most succulents, it requires very infrequent watering (about once a month), a few hours of direct sunlight and is not affected by humidity. Good soil drainage is essential to prevent root rot, so sandy soil is recommended. This plant can be propagated easily by cutting or pinching off 10 cm or 4 inches of healthy stem tip and lightly covering them with a moist potting mix. The roots will quickly develop from where the leaves are attached to the stem.
II. Types of String of Pearls Plant
There are several closely related plants to String of pearls that feature differently shaped leaves, looking more like bananas, teardrops, or watermelons with stripes. These close cousins in the same daisy family include:
- Curio radicans: Fuller and not as trailing as string of pearls, this varietal has tendrils with banana-shaped leaves; commonly called string of bananas or string of fish hooks.
- Curio herreanus: Commonly called string of watermelon or string of beads, this trailing plant has tiny melon-shaped leaves with purple striping.
- Curio citriformus: This varietal has both erect and trailing stems filled with plump, teardrop leaves and small white flowers that bloom between late summer and winter.
III. How to Grow and Care
Sunlight
String of pearls plants thrive on a combination of direct and indirect sunlight, totaling between six and eight hours a day. They’re best when kept in direct sunlight during the softer morning hours, then moved to a spot that gets diffused, indirect light, or partial shade during the harsher afternoon hours.
Temperature and Humidity
String of pearls plants thrive in warm temperatures above 70 degrees Fahrenheit from spring through fall, and it grows best with winter temperatures, ranging from 50 to 60 degrees Fahrenheit. This plant prefers low humidity, so avoid placing it in any already-humid areas of your home, like a kitchen or bathroom.
Watering
Keep the plant’s soil lightly moist during the growing season in the spring and summer, then reduce water during the winter months. If you notice the succulent’s spherical leaves flattening, it’s a good indicator that the plant needs more water. You will likely need to water your plant once every seven to 14 days. Plants in hotter climates, outdoors during the summer, or in porous terra-cotta pots might need water closer to every seven days, all depending on rain frequency and temperatures. If the soil is dry to the touch down to the first one-half inch of soil, that’s a good sign your plant is thirsty.
Water thoroughly; you’re done watering once the water drains out of the bottom of the pot. Succulents need good drainage and be careful not to overwater your string of pearls plants. Succulents are drought-resistant but cannot survive with wet, soggy roots.
Soil
Any regular succulent potting soil is acceptable for your string of pearls plants, but sandy soil is best. A good choice for this plant is a cactus potting mix. Alternatively, use a three-to-one mixture of potting soil to sharp sand. These plants are susceptible to root rot, so make sure their soil is well-draining. Plant them in a container that boasts ample drainage holes at its base. Terra-cotta or clay pots also help wick away excess moisture from the soil.
Fertilizing
Feed your string of pearls plants biweekly during the growing season with a balanced liquid or water-soluble fertilizer, diluted to about half strength. During its dormant winter period, only feed the plant every six weeks.
Pruning
Using sterilized scissors or pruners, trim off any dead stems and pearls, as well as any stems that have lost a lot of their leaves. If your plant is getting leggy or too long, trim those branches and propagate new plants from the cuttings. Pruning will promote fuller, bushier plants.
Propagation
String of pearl plants are easily propagated in soil, on soil, or from stem cuttings. To keep your plant alive for years, you’ll want to take cuttings and make new plants. Spring, summer, or early fall (in warmer climates) are good times to propagate a string of pearls plant. It takes three to four weeks for the plant to take root. Propagation from seeds is less successful. Here’s how to grow plants from cuttings:
- To propagate a string of pearls plant, you will need sterilized pruning snips or scissors, a four- or six-inch pot, and cactus or succulent soil.
- Cut several four- to five-inch stems just below a leaf node. Remove the last two leaves. Lay out the stems for about one to two days before planting. The cut ends and areas where the leaves were removed need to callus over and get dry.
- Fill a pot with soil. In the center, make a hole where you will plant the stems.
- Place the cut ends into the hole at least an inch deep. All leaves should be above the soil. Pack the dirt around the stems. Wait a few days before watering thoroughly.
- If indoors, place it in a bright spot. Outdoors, the plant does better in partial sun. Water the soil when it dries up.
Potting and Repotting
The ideal time to repot your string of pearls plant is at the beginning of spring. Use a fast-draining succulent or cactus soil mix. Get a well-draining pot with ample drainage holes. Terra-cotta and unglazed ceramic pots are ideal for succulents. The pot should be the next size up from the pot you currently have, usually two to three inches larger and deeper. Add the soil to the bottom of the pot, gently remove the root ball from the old pot and center it on the bed of fresh soil. Fill the soil around the root ball up to one inch below the lip of the pot.
You can repot these plants annually but only a few times before they eventually begin to die back. After a few years, it’s better to propagate a plant from new cuttings rather than trying to preserve and replant an older plant.
Overwintering
If you live in zone 8 or below, bring your string of pearls plant indoors during the winter; it will not survive a freezing winter outdoors. If you want your plant to eventually bloom, give it a cool-down period with temperatures just above freezing between 35 to 44 F. Keep the plant in a non-heated room that gets at least six hours of light, providing it the cool period it needs. Water very rarely—about once per month during the dormant period.
Pests and Diseases
- Common Pests
The two most likely String of Pearls pests are mealybugs and aphids.
The best way to deal with bugs on your Curio rowleyanus is by preventing them from turning up in the first place.
A monthly spritz of an insecticidal solution such as neem oil or insecticidal soap is your best bet to keep these insects at bay.
However, if they slip past your defenses, you should be able to easily get rid of them.
Mealybugs will resemble little tufts of cotton on the leaves and stems. Spray them with rubbing alcohol to kill them.
Aphids are small, green flying insects. Give your String of Pearls a gentle spraying in the sink or shower to clean them off.
- Common Diseases
There are very few String of Pearls diseases to worry about.
In fact, the only disease you’re likely to see affecting your Curio rowleyanus is the classic houseplant nemesis, root rot.
This is caused by leaving the roots of String of Pearls sitting in wet soil, cutting off their ability to breathe and fostering fungal diseases.
If the leaves start turning yellow, and stems are getting mushy, pull the root ball out and see if there are black sections.
Cut out all the affected roots, stems, and leaves, and replant your String of Pearls in porous, loose soil in a disinfected pot.
- Growing Problems
Most growing problems with String of Pearls aren’t caused by diseases or pests, but are rather the result of poor growing conditions.
When your sick plant is given a more ideal situation, it should come roaring back to health.
Shriveled leaves are a clear indication that your String of Pearls needs water. When even its succulent tissues have run out of moisture, it’s time to give it a good drink.
Browning leaves are usually caused by too much direct sun. Move it away from the window or hang a light curtain to shade it slightly.
If your String of Pearls’ crown is rotting, it’s planted too deep in the pot. You may not be able to rescue it, so take some healthy stem cuttings and propagate them to replace the rotted plant.
IV. Uses and Benefits
String of Pearls is a fascinating plant that can be used in a variety of settings to complement a contemporary or cottage-core decor.
Indoors, you can hang your String of Pearls planter in front of a south window to screen an unattractive view.
Because they’re so easy to propagate, you can work with multiple plants to create a wall of trailing greenery for a living tapestry.
Outdoors in zones 9 to 12, you can let String of Pearls spread across rocks or gravel to form a solid mat of ground cover or hang a whole row as a backdrop on a sunny porch.
