Curio rowleyanus: watering a plant with no leaves on its surface
String of pearls has no functional leaf blade in the usual sense — the sphere is the leaf. That single fact explains nearly every way people kill it: the surface never looks dry, and the plant has no way to signal thirst until the pearls visibly shrink.
The sphere is a leaf, and that changes the watering test
Each pearl is a fully enclosed leaf with a narrow translucent window on the far side for light entry. There is no flat lamina and therefore no large evaporative surface, so the mix under the plant stays damp far longer than it looks. A 15 cm basket in summer takes 18–22 days to dry at 24 °C.
The reliable test is the pearls themselves. A watered pearl is a firm, glossy sphere about 6–8 mm across. A thirsty one loses turgor from the base of the strand upward, developing a slight crease and then a visible dimple on the underside. Water when the pearls at the top of the strand — nearest the soil — soften, not when the tips do.
Never water overhead, and the reason is the crown
The crown where the strands emerge is a tight rosette of nodes sitting directly on the mix surface. Water pooling there at 20–25 °C causes stem rot in about five days, and by the time you see a strand collapse the rot has already reached the root crown. Water at the pot rim with a narrow spout, and stop as soon as liquid appears in the saucer.
Do not leave a saucer full: this species has fine roots in the top 4 cm and almost nothing below, so standing water in the lower profile does nothing but breed fungus. Tilt the pot, drain, and put it back.
Summer dormancy and the June to August rule
Between roughly 15 June and 20 August at temperatures above 28 °C, string of pearls effectively stops. Growth is nil, water use drops by half again, and the plant is at its most rot-prone. In that window, water every 25–30 days, in the evening, and move it out of afternoon sun — pearls scorch at the contact point and the scar persists.
Contrary to a lot of advice, this is not "rest completely". A plant left bone dry at 30 °C for ten weeks desiccates the strand bases and they never rehydrate. The goal is a mix that is dry at the surface and barely damp at 3 cm.
Restarting a thin, balding strand
Strands go bald from the crown outward when the plant is under-watered or the light is one-sided. Fix the cause first — usually light: the strand tips need 20,000–40,000 lux, not a shelf 2 m from a window.
Then lay, do not cut. Coil a healthy 30 cm length on the mix surface and pin it down with a bent paperclip every 8 cm. Roots form at the pinned nodes in 21–30 days at 22–25 °C, and each pinned node throws a new vertical strand. Once the new strands are 5 cm long, sever the original strand between nodes and you have four or five independent plants.
Parameter table
- Latin name
- Curio rowleyanus
- Common name
- String of pearls
- Rosette form
- trailing
- Light range
- 20,000–40,000 lux
- Water interval
- 20 days at 24–28 °C
- Rest period
- Rest period June to August; expect almost no growth in the hottest weeks
- Hardiness
- 9b–11 (damage below 0 °C)
- Offset behaviour
- Roots at every node that contacts mix; stems break off and self-root, but no basal offsets
- Soil mix (by volume)
- 3 pumice : 1 akadama : 1 coco coir — deliberately lean
- Mature diameter
- 90 cm
| Month | State | What the plant wants |
|---|---|---|
| January | Growth | Deepest rest. Water only if the lowest leaf ring softens; keep the room as bright as you can. |
| February | Growth | Late rest. Daylight is returning — begin adding an hour of supplementary light every two weeks. |
| March | Growth | Repotting window opens for summer growers. Trim roots, refresh the mineral fraction, dry for a week. |
| April | Growth | Growth restarts. First full watering at the rim, then resume the published interval. |
| May | Growth | Peak growth and the offset season. Feed at quarter strength every third watering. |
| June | Rest | Out of action for this genus — no water unless the plant visibly shrinks, and no repotting. |
| July | Rest | Out of action for this genus — no water unless the plant visibly shrinks, and no repotting. |
| August | Rest | Out of action for this genus — no water unless the plant visibly shrinks, and no repotting. |
| September | Growth | Autumn window for winter growers. Root-prune and repot while the soil is still warm. |
| October | Growth | Peak autumn growth. This is the season when most colour work should be done. |
| November | Growth | Daylight falls fast. Taper watering by a quarter and stop feeding entirely. |
| December | Growth | Slow, dry and bright. This is the colour peak for most genera in the collection. |
Tinted rows are the months this genus is genuinely out of action: no repotting, no feeding, and water only if the plant visibly shrinks.
Four things to take away
- The pearl is the leaf; the surface never reading dry is not a signal.
- Test the pearls nearest the soil, not at the strand tips.
- The crown is the rot entry: never water overhead, never leave a full saucer.
- Lay and pin strands rather than cutting — rooted nodes in 21–30 days.
Informational only — This page is a cultivation record, not horticultural or plant-pathology advice. Any treatment should follow the product label and local regulation.