Rope hoya (Hoya carnosa 'Compacta')

Meet the plant

A form of the common wax plant whose thick, dark green leaves fold, curl and pucker back on themselves and never open flat, packed so close along the stem that each one reads as a living rope (NC State Extension, Pistils Nursery, RHS profile). It is sold as Hoya compacta, Hoya carnosa var. compacta and 'Krinkle Kurl'; all are the same plant (RHS profile, ASPCA). It is usually grown in a hanging pot, the ropes arching over the rim and falling.

It is slow. The RHS rates it a slow-growing climber that takes five to ten years to reach half a metre to a metre (RHS profile). It wants the same conditions as the wax plant, and growers call it a great plant whose one real enemy is mealybugs, which hide in its tight folds (Vermont Hoyas, compacta). The ASPCA lists it by name as non-toxic to cats and dogs, as it does the plain wax plant (ASPCA, wax plant, ASPCA, honey plant); the milky sap can irritate skin, so wear gloves when you cut it (RHS growing guide).

You will usually buy a small pot of a few short ropes. What to expect in a year: a few centimetres more on each rope, a new rope now and then from the crown, almost nothing in winter. That is a healthy plant. Flowers usually begin at two or three years (Vermont Hoyas, compacta, NC State Extension).

Light

Bright, indirect light, close to an east or west window, with shade from hot sun (RHS profile, NC State Extension). The RHS lists it for sun or part shade in a sheltered spot, and a little gentle morning or evening sun suits it once it is used to it (Pistils Nursery). Move it into stronger light over a couple of weeks, not in one go (Clemson HGIC).

Too much sun shows as bleached or brown crisp patches (Iowa State Extension). Too little slows a slow plant to a standstill, and the new growth comes with more stem showing between the leaves, so the rope loosens. Light is also the first thing to change when it will not bloom (UF/IFAS Gardening Solutions).

Water

Check first. Push a dry finger as far into the mix as it will go, and lift the pot: learn what it weighs wet and dry (Vermont Hoyas, watering, Clemson HGIC). Dry all the way down and light means it is time. Any dampness means wait. The leaves are crinkled by nature, so learn how they look and feel when the plant is well watered: softer leaves and deeper wrinkles than usual are the signal, as puckering is on any hoya (Pistils Nursery).

The rule: water thoroughly, until it runs out of the bottom, once the mix is almost dry, then let it dry again (Iowa State Extension). Do not water in sips (Vermont Hoyas, watering), and use room-temperature water, because cold water shocks the wax plant (NC State Extension). Sources differ. Vermont Hoyas finds this cultivar tolerates a little more water than the plain wax plant (Vermont Hoyas, compacta), and the RHS says water moderately in growth (RHS profile); the extension pages say let the mix dry almost completely. This guide takes the dry side, because the tightly packed leaves keep the base of the plant shaded and slow to dry, and rot there is hard to see until late.

Thirsty: leaves softer and more wrinkled than their usual folds, dull, on a dry, light pot. A soak brings them back over a few days. Overwatered: leaves yellowing along the ropes while the mix is still wet, soft leaves dropping, limp ropes, a dark base (Iowa State Extension, NC State Extension). If the leaves say thirsty and the soil says wet, believe the soil and look at the roots.

How often that lands depends on the pot, the mix, the light and the room. In a chunky mix in bright light in summer it often comes round every week and a half to two and a half weeks, longer than for a leafier plant of the same size; no source gives a figure for this cultivar. In winter the plant rests and wants water very sparingly (UF/IFAS Gardening Solutions); the RHS keeps the compost just moist (RHS profile). Dry heated air can empty a pot faster than you expect (Vermont Hoyas, watering), but in a cool room err dry. Treat the numbers as a reminder to check, not as the instruction.

Soil and pot

A chunky, fast-draining mix: equal parts orchid bark, peat-free compost and coarse perlite (RHS growing guide, Clemson HGIC). The RHS profile asks for a fast-draining, loam-based compost with extra organic matter (RHS profile); hoya growers go chunkier, mostly perlite and bark with some compost (Vermont Hoyas, medium). Every mix breaks down into fine material that holds water, so refresh it every few years even if the pot stays the same (Vermont Hoyas, medium).

The pot needs a drainage hole and should be snug, usually a hanging one. Hoyas flower better slightly pot-bound, and a pot too large keeps the mix wet (Iowa State Extension, Clemson HGIC). The RHS says hoyas dislike repotting and can stay in one pot for many years, and Vermont Hoyas keeps carnosa types in the same pot for years (RHS profile, Vermont Hoyas, repotting). When you do move up, go one size, 2 to 4 cm wider. Plastic lets you judge the weight; Vermont Hoyas finds bare terracotta dries a chunky mix too fast. Either works if you check before you water.

Repot in spring, never while the plant is in bud or bloom (RHS growing guide). Handle the ropes gently; the folded leaves knock off. Soak it in, then wait until the new mix is nearly dry before watering again: the first two months are when overwatering does the most harm (Vermont Hoyas, repotting). Hold the feed for five or six weeks (RHS growing guide).

Feeding

Lightly. A balanced liquid houseplant or orchid feed at half strength every four to six weeks from spring to early autumn, and nothing in winter (Iowa State Extension). The RHS feeds monthly in growth for this cultivar and, in its general hoya guide, monthly through winter too (RHS profile, RHS growing guide); Iowa State stops for the winter rest. This guide stops, the weaker rule, and a plant this slow uses little feed. Every few months water through with plain water to wash out salts (RHS growing guide).

Flowering

Domed clusters of small waxy stars with a red centre, from spring to autumn (RHS profile); in the wax plant they are pale pink or white (RHS growing guide). Sources disagree on scent: the RHS calls them fragrant, while Vermont Hoyas finds no detectable scent on its plant (Vermont Hoyas, compacta). They usually begin when the plant is two or three years old (NC State Extension).

What it takes: a plant of a few years, bright light with a little gentle sun, a snug pot, and a cooler, drier, unfed winter (Iowa State Extension, UF/IFAS Gardening Solutions).

Two things never to do. The flowers grow from short spurs tucked among the folded leaves, and the same spur flowers again year after year. When the flowers fall, leave the spur alone: cutting it off is cutting off future flowers (NC State Extension, RHS growing guide). And once buds appear, do not move or turn the plant until the flowers are over; a moved hoya drops its buds (RHS growing guide, Iowa State Extension).

When something looks wrong

Look at the soil first, and then look into the folds.

• Softer, more wrinkled leaves than usual. Check the mix. Dry and light: soak it through and the leaves firm up over a few days. Wet: the roots are damaged; let it dry almost completely and slide it out to look (Iowa State Extension).
• Yellow leaves along the ropes, mix wet. Overwatering, a pot too large, or a mix that has broken down (Clemson HGIC, Iowa State Extension). Stop until nearly dry, check that water runs freely out, and repot into fresh airy mix in a snug pot if the mix is compacted.
• Mealybugs. White cottony tufts deep in the folds and the leaf joints. They are this plant's main trouble, because they hide in its crevices, and many growers have given up on it because of them (Vermont Hoyas, compacta, RHS profile). Part the leaves and look along every rope. Dab each one with a cotton bud in rubbing alcohol, spray the whole plant with insecticidal soap, repeat weekly for several weeks, and keep it apart until clear (Clemson HGIC, UF/IFAS Gardening Solutions).
• Loose ropes with stem showing. Too little light. Move it closer to a window; new growth comes tighter.
• No growth for months. Often nothing is wrong: it is slow by nature and slower in winter (RHS profile). More light and warmth, a light feed in summer and a fresh mix if the old one has compacted are what help.
• No flowers. Light first, then patience, then the spurs: were they cut? Stop feeding in winter and give it a cooler rest (Iowa State Extension).
• Buds drop before opening. The plant was moved, the watering changed, or the temperature swung (Iowa State Extension, RHS growing guide). Leave it where it is until it has finished.
• Bleached or brown crisp patches. Hot sun through glass (Iowa State Extension). Move it back or filter the light.
• Scale. Small hard brown bumps with sticky residue (Iowa State Extension). Wipe or scrape them off, then wipe with insecticidal soap or horticultural oil and repeat.
• Spider mites. Pale speckling and fine webbing in dry warm air (Clemson HGIC, NC State Extension). Shower the plant into the folds every few days, spray with insecticidal soap or neem weekly, and raise the humidity.
• Black mushy base, ropes limp on wet mix. Root rot. Cut away every dark soft root, repot in fresh, barely damp mix in a snug pot, and take cuttings of healthy rope straight away: a plant this far gone often does not recover (RHS growing guide, Clemson HGIC).

Propagation

By stem cuttings, in spring or early summer. Take a length of rope with two or more nodes; wear gloves for the sap. Push it into moist perlite up to the first leaves, keep it warm and humid under a clear cover in bright indirect light, and expect roots in four to six weeks (Vermont Hoyas, propagation), or stand it in water, where hoya cuttings root in two or three weeks (RHS growing guide). The RHS also takes semi-ripe cuttings with bottom heat in late summer, or layers a rope in spring or summer: pin it to a pot of mix beside the plant and cut it free once rooted (RHS profile). A cutting of a slow plant grows on slowly; several in one pot make a fuller plant sooner.