String of Pearls vs String of Hearts: One Is Notoriously Difficult — the Other Forgives Mistakes
String of pearls vs string of hearts: both trail beautifully, but one kills from overwatering in days and is toxic to pets. Here’s exactly how they differ.
Both plants trail from a shelf in a cascade of ornamental stems. Both came from South Africa. And both are sold in the same section of every plant shop. The similarity ends there.
String of pearls (Curio rowleyanus) and string of hearts (Ceropegia woodii) belong to completely different plant families, evolved in different habitats, and have opposite tolerances for the mistake most houseplant growers make: too much water. Treat them the same way and you will kill one of them. Here is everything you need to tell them apart and grow both well.
Quick Comparison: String of Pearls vs String of Hearts
| Feature | String of Pearls | String of Hearts |
|---|---|---|
| Scientific name | Curio rowleyanus | Ceropegia woodii |
| Plant family | Asteraceae (daisy) | Apocynaceae (milkweed) |
| Trailing length | Up to 3 feet (90 cm) | Up to 9 feet (3 m) |
| Light | Bright indirect, 6+ hours | South or west window, 3–4 hours direct |
| Watering | Bone dry between waterings | Top two-thirds dry between waterings |
| Difficulty | Moderate (very sensitive to overwatering) | Easy to moderate |
| USDA zones (outdoor) | 9b–11b | 10–12 |
| Pet safety | Toxic to cats and dogs | Non-toxic to cats, dogs, and horses |
| Typical retail cost | $8–$18 (4-inch pot) | $6–$16 (4-inch pot) |
Origins: Same Continent, Different Worlds
String of pearls is native to the Cape Provinces of South Africa, where it grows in open, arid scrubland. There, the stems trail across dry, sandy ground, rooting at nodes to form dense mats. It evolved under intense sun with minimal water and no shelter from frost-free but very dry conditions.
String of hearts comes from a different South African landscape entirely. Its range stretches from the Eastern Cape north through KwaZulu-Natal, Limpopo, and Mpumalanga into Eswatini and Zimbabwe, where it clings to rocky ledges within forest margins at elevations between 330 and 3,900 feet (100–1,180 m). It evolved in bright but partially sheltered conditions, with annual rainfall of 24–40 inches (600–1,000 mm).
These different origins explain their different tolerances. String of hearts evolved where rain comes seasonally and the rocky habitat drains fast, but moisture is not as scarce as in SOP’s scrubland. String of pearls evolved in one of the driest conditions of any popular houseplant.
They are also not related. String of pearls belongs to Asteraceae, the same family as daisies and sunflowers. String of hearts belongs to Apocynaceae, the milkweed and dogbane family. Their trailing habit is convergent evolution, not kinship.
The Biology Behind the Look
Understanding why each plant looks the way it does explains most of the care rules that follow.
The SOP pearl is an engineering solution to a desert problem. A sphere has the lowest possible surface area per unit of volume of any three-dimensional shape. By packing water storage into spherical leaves, string of pearls exposes the minimum amount of leaf surface to dry desert air, dramatically reducing evaporative water loss. But a sphere with a solid outer layer cannot photosynthesize efficiently. Each pearl solves this with a narrow, translucent, crescent-shaped band of tissue on its upper surface—an epidermal window that channels light into the leaf interior, as documented by botanist R.B. Kaul in the Canadian Journal of Botany in 1980. The dark green stripe you see on each pearl is that window. Damage the pearls (by rough handling, sunburn, or rot) and the photosynthetic system breaks down.
String of hearts stores its insurance underground. At the base of a mature plant, and at intervals along the stems, C. woodii produces tubers. The base corm grows woody, grey, and wrinkled with age, typically reaching 1–2 inches (25–50 mm) in diameter, according to SANBI. Along the stems, smaller aerial tubers form warty, potato-like growths that store water and carbohydrates through dry periods. This reserve is why string of hearts is more forgiving of an overdue watering or a slightly too-moist potting mix: the plant has a buffer that string of pearls simply lacks.
The silver marbling on string of hearts leaves is not decorative—it reflects excess light. In lower light, the marbling fades and leaves turn pale green. In good light, the marbling intensifies and the undersides turn purple-pink, an anthocyanin response to UV exposure.
Light Requirements
String of pearls needs the brighter setup of the two. Aim for six or more hours of bright indirect light per day, with an east or west window position being ideal. Morning direct sun is fine; harsh afternoon direct sun can bleach or shrivel the pearls. If pearls start elongating and spacing out on the stem—a condition called etiolation—the plant needs more light, not more water.
String of hearts performs best in a south or west-facing window where it receives three to four hours of direct sun daily. Wisconsin Horticulture Extension notes that in strong light the leaves develop their darkest color and most vivid silver marbling; in low light, the leaves turn a washed-out light green. Both plants can adapt to indirect bright light, but string of hearts is slightly more tolerant of lower light intensities without losing its growth momentum.
Watering: The Biggest Difference Between These Two Plants
This is where most growers go wrong, and where the two plants diverge most sharply.
String of pearls has essentially no buffer against overwatering. Its shallow, fine root system is exquisitely sensitive to soggy soil, and root rot progresses within days once it begins. Wisconsin Horticulture Extension is clear: allow the potting medium to dry out completely between waterings. The best indicator is the pearls themselves—when they begin to look slightly shriveled rather than taut and glossy, it is time to water thoroughly, then wait for complete dryness again. During winter, at temperatures of 55–60°F (13–16°C), water extremely rarely. The plant is resting and barely transpiring.
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String of hearts is more forgiving, but only relatively speaking. It still needs excellent drainage and cannot sit in wet soil. The guideline from SANBI is to allow the top two-thirds of the potting mix to dry before watering. During the growing season (spring through summer), it tolerates slightly more frequent watering than SOP. In winter, reduce watering significantly. The tuber reserves mean a missed watering is rarely fatal; a missed drainage hole absolutely can be.
A practical test for either plant: lift the pot. If it feels light, water. If it still feels heavy, wait. For more detail on watering succulents correctly, the principle of weighing the pot before watering applies to both species.
Soil and Containers
Both plants demand sharply draining soil, but the mix can differ slightly.
For string of pearls, go as lean as possible: a 50/50 blend of cactus mix and inorganic material such as pumice, perlite, or coarse horticultural grit. Wisconsin Horticulture Extension recommends additions of up to a 1:1 ratio of inorganic material. Terracotta pots are ideal because they allow moisture to evaporate through the pot walls, reducing the window during which roots sit in damp conditions.
String of hearts tolerates a slightly more structured mix. SANBI recommends equal parts soil-based potting mix, coarse sand, and perlite—giving it better water retention than pure cactus mix while still providing the drainage it needs. Either plant will rot in standard houseplant potting soil without amendment.
Repot string of pearls every one to two years in spring, or when the soil seems to stay damp for more than a week after watering. Repot string of hearts when the aerial tubers begin crowding the pot surface or roots appear through drainage holes.
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Temperature and Outdoor Growing Zones
String of pearls is slightly more cold-tolerant between the two, handling temperatures down to around 50°F (10°C) and suitable for outdoor growing in USDA zones 9b–11b. Below that, it needs to come indoors. A cool winter at 55–60°F (13–16°C) may actually trigger the small white, cinnamon-scented flowers that rarely appear indoors in warmer conditions.
String of hearts requires a minimum of 59°F (15°C) for outdoor cultivation and is suited to USDA zones 10–12. At its native elevations in South Africa, temperatures rarely drop below 61°F (16°C). Neither plant tolerates frost. In most of North America, both are year-round houseplants.
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→ Find the Right PotToxicity and Pet Safety
This is the most practically important difference for many households, and it is one that most comparison articles miss entirely.
String of pearls is toxic to cats and dogs. The ASPCA lists it as toxic, with ingestion potentially causing vomiting and gastrointestinal upset. UC Davis classifies it as Class 2 (minor toxicity causing vomiting or diarrhea) and Class 4 (skin irritant—the sap can cause dermatitis in sensitive individuals). Keep it well out of reach of pets and wash hands after handling.
String of hearts is non-toxic to cats, dogs, and horses according to the ASPCA. This single difference makes string of hearts the automatic choice for homes with curious pets. If a cat bats the trailing stems down and chews on them, there is no toxic risk. For more pet-safe plant options, both trailing and upright, there are good alternatives that share string of hearts’ easy-going temperament.
Propagation
Both plants propagate easily, but string of hearts gives you more methods to work with.
For string of pearls, take 3–4 inch stem tip cuttings in spring or summer. Strip the bottom three or four pearls from the stem to expose the nodes, then lay the cutting on the surface of moist cactus mix or tuck the bare nodes just under the soil. Roots develop quickly at the nodes. Do not place cuttings in water—the stems are prone to rotting before roots form in aquatic conditions.
String of hearts offers three propagation routes. Stem cuttings root well with bottom heat—a heating mat set to 70–75°F (21–24°C) accelerates rooting. The aerial tubers are the easiest method: simply press one of the warty growths on the stem against moist soil while still attached to the parent plant. It will root within a few weeks, at which point you can sever the connecting stem. You can also remove the tuber entirely and plant it directly, as Wisconsin Horticulture Extension notes. String of hearts also produces seed after its small tubular trap-flowers—pink and purple with downward-pointing interior hairs that guide pollinators—are pollinated, though seed-grown plants take longer to establish.
Which Should You Choose?
The answer depends on three factors: pets, patience, and light.
Choose string of hearts if: you have cats or dogs, you want faster growth and longer trailing stems, you prefer more propagation options, or your sunniest window is south- or west-facing. Its tuber buffer makes it more forgiving of the inconsistent watering that trips up new succulent growers. It is also faster-growing—a 4-inch pot can cascade two to three feet within a season in good light.
Choose string of pearls if: you have no pets, you have a very bright east or south-facing window, and you can commit to a strict watering discipline. The architectural look of the pearl strands is unmatched, and the occasional fragrant white bloom in a cool winter is a reward for patience. For a full guide to growing it, see the complete string of pearls care guide.
Both plants belong in the same indoor succulents care framework—bright light, sharply draining soil, and a cautious hand with the watering can. The difference is how much margin for error each plant gives you when you misjudge.
Frequently Asked Questions
Can you grow string of pearls and string of hearts in the same pot? It is not recommended. Their watering requirements are close but not identical—sharing a pot means you cannot optimize drainage for each. More importantly, SOP is toxic, so a shared pot in a pet household creates a risk even though SOH is safe.
Which is easier for complete beginners? String of hearts. Its tuber reserves give it more tolerance for uneven watering, and it grows fast enough that you get immediate feedback on whether your care is working. String of pearls demands more precise watering discipline from the start.
Why are my string of pearls pearls shriveling? If they are soft and mushy, the cause is overwatering and likely root rot—check the roots for brown, slimy tissue and repot into dry fresh mix immediately. If they are firm but slightly wrinkled, the plant is underwatered—water thoroughly and the pearls should plump back within 24 hours.
Why is my string of hearts losing its silver markings? The silver marbling is a light response. Move the plant to a brighter south or west window with at least three hours of direct sun. The coloration intensifies as the plant produces more chloroplasts and anthocyanins in response to higher light intensity. Low-light leaves revert to pale, unmarked green.
Sources
- Wisconsin Horticulture Extension. String of Pearls, Senecio rowleyanus. University of Wisconsin-Madison
- Wisconsin Horticulture Extension. String of Hearts, Ceropegia woodii. University of Wisconsin-Madison
- South African National Biodiversity Institute (SANBI). Ceropegia linearis subsp. woodii. PlantZAfrica
- Wikipedia contributors. Curio rowleyanus. Wikipedia, The Free Encyclopedia
- Wikipedia contributors. Ceropegia woodii. Wikipedia, The Free Encyclopedia
- ASPCA Animal Poison Control Center. String of Pearls (Curio rowleyanus) — Toxic to cats and dogs. aspca.org
- Kaul, R.B. (1980). Light Transmission in Window-leaved Plants. Canadian Journal of Botany, 58(16).
