Syngonium

Light and exposure

The syngonium likes bright but filtered light, never direct sun, which scorches its foliage and washes out the colours. Place it near an east-facing window, or a little back from a south or west window behind a sheer curtain. Varieties variegated with pink or white need slightly more light to keep their tints, while the plain green ones make do with a more modest spot.

Under our often grey Belgian skies, especially from October to March, move the plant closer to the window to make up for the lack of brightness. A syngonium that stretches out with long bare stems and small leaves is simply asking for more light. Turn the pot a quarter turn each week so it grows straight and even.

Watering

Water when the top few centimetres of the substrate start to dry out. The syngonium likes a potting mix that stays slightly moist in spring and summer, without ever getting soggy. Always empty the saucer after watering, because roots left standing in water eventually rot. Water at room temperature, left to sit so the chlorine escapes, suits it better than cold tap water.

In winter the plant slows down and drinks far less: space the waterings out clearly and let the surface dry more between them. The heating dries out the air in our homes, so the plant enjoys a little ambient humidity. Mist the foliage, set the pot on a bed of damp clay pebbles, or place it near other plants to create a microclimate.

Soil and repotting

A light, free-draining potting mix for foliage plants does the job perfectly. Lighten it with a handful of perlite or a little fine bark so water passes through well and the roots can breathe. The syngonium dislikes a heavy, compact substrate that holds water against its roots.

Repot in spring, every one to two years, into a pot barely larger with a hole at the bottom. The plant grows fast and fills its pot with roots: when they poke out through the drainage holes, that is the sign it is time. A layer of clay pebbles at the bottom of the pot helps drain off excess water, valuable in winter when everything dries more slowly.

Temperature and humidity

The syngonium is a tropical plant that thrives between 18 and 27 degrees, exactly the temperatures of our homes. It dislikes dropping below 15 degrees and clearly suffers under 12 degrees, with leaves that go limp and blacken. Frost kills it outright.

In Belgium that means one simple rule: it stays indoors all year. Never leave it outside, not even in summer, because our cool nights wear it out and one forgotten evening on the terrace in late August can be fatal. Keep it away too from cold draughts near doors and poorly insulated windows in winter, and from direct contact with an icy pane at night.

Pruning and upkeep

The syngonium prunes very easily and takes it well. Pinch or cut the overly long stems just above a node to keep a compact, bushy plant. Without pruning it tends to lengthen and climb or trail in long vines, which can look pretty as a hanging plant but goes bare in the centre.

You choose its look: let it trail from a shelf, or give it a moss pole to climb, which pushes the leaves to grow larger and more deeply divided. Over time remove the yellowed or damaged leaves at the base. Every cut stem is a potential cutting, so throw nothing away.

Pests and diseases

The main trouble comes from too much water: rotting roots and crown, soft stems, leaves yellowing in numbers. It is almost always a matter of overly generous watering or a saucer never emptied. Put it right by letting it dry out, and repot into fresh substrate if the smell of waterlogged soil is already there.

As for pests, watch for spider mites, which appear when the air is too dry and warm, recognisable by their fine webs and speckled foliage. Mealybugs, small cottony clusters in the leaf axils, sometimes turn up too. Shower the plant, raise the ambient humidity, and dab the mealybugs with alcohol on a cotton bud. Brown, dry leaf tips almost always give away air that is too dry, typical of our heated homes in winter.

Propagation

Water propagation is disarmingly simple and it is the greatest pleasure this plant offers. Cut a stem bearing one or two nodes, just below a node, and remove the bottom leaf. Look for the little aerial roots that often already poke out at the nodes, they are the ones that will get going.

Place the cutting in a glass of clean water, in filtered light, and change the water every few days. Roots appear in one to two weeks. When they reach four to five centimetres, pot up into a small pot of light mix and keep the substrate moist while the plant settles in. You can also take cuttings straight into soil, but water lets you follow the rooting by eye and reassures beginners.

Toxicity

Syngonium is toxic if eaten and irritating on contact. Like most aroids, it holds needle-shaped crystals of calcium oxalate (raphides) throughout its leaves and stems. Biting or chewing a piece triggers an immediate burning feeling in the mouth, heavy drooling, swollen lips and tongue, and sometimes trouble swallowing. The sap can also irritate the skin and cause redness in sensitive people.

Keep the plant out of reach of young children, cats and dogs, who like to nibble the tender foliage. It is not a deadly poison at the usual doses, but the discomfort is real and sometimes alarming. Wear gloves if your skin reacts easily, and wash your hands after pruning or taking cuttings.

Month-by-month care calendar

Green Hub tips

• Keep the syngonium out of reach of children and pets: its irritating sap burns the mouth if chewed.
• A moss pole makes the plant climb and its leaves grow bigger, a hanging basket makes it trail in a cascade. The look is yours to choose.
• Brown leaf tips in winter? That is the dry air from the heating. Mist it or set the pot on damp clay pebbles.
• Throw away no trimmed stem: a cutting in a glass of water roots in two weeks and gives you a new plant for free.