Chinese evergreen care: light, water and cold protection

Light

The University of Illinois Extension puts aglaonema in its low-light group, around 75 foot-candles, and singles out the shadowless light of a north window. UF/IFAS research goes further: established plants tolerate as little as 25 foot-candles, which is why the genus became a staple of commercial interior plantings. Clemson recommends low to moderate indirect light and warns against direct sun, which scorches the leaves.

Colorful cultivars change the picture. UF/IFAS advises bright, indirect light for high-color selections, and Clemson notes that variegated types need more light than solid greens. Too much light has its own telltale sign: UF/IFAS describes leaves that fade and stand stiffly upright instead of at their usual 45 to 90 degree angle from the stem. Rotating the pot every week or two, as professional plant-care crews do, keeps the clump symmetrical.

Water

Clemson's guidance is to keep the soil evenly moist but not wet, letting the top 1 to 2 inches dry before watering; UF/IFAS Gardening Solutions sets the trigger at the top inch feeling dry. Clemson suggests testing with two fingers pushed about 2 inches into the pot. Use water at room temperature: NC State specifically warns against cold water, a sensible precaution for a plant this sensitive to chilling.

For its size, aglaonema needs little water, and UF/IFAS cautions that overwatering is the usual trigger for root rot and yellowing leaves. NC State notes that it does not require a winter dormancy, unlike some aroids, but it benefits from less water in winter, when light is weaker and the mix dries slowly. The University of Illinois Extension even lists growing it in plain water as an option, a sign of how well the roots tolerate moisture as long as they are not suffocating in compacted, sour soil.

Soil and pH

Clemson recommends a standard soilless mix with extra humus, and Illinois likewise describes a humus-rich potting soil. UF/IFAS adds that aglaonema accepts almost any fertile medium, from peat and perlite to sand or loam, and that commercial growers use peat, pine bark, vermiculite or perlite with 10 to 20 percent air space. On acidity the sources differ slightly: NC State lists acidic soil, while UF/IFAS production guidelines target pH 6.0 to 6.5. A standard houseplant mix sits comfortably in that zone. Use a pot with a drainage hole.

Humidity

Despite its rainforest origins, aglaonema tolerates the dry air of most homes. Clemson says it tolerates low humidity but prefers moderate levels, and UF/IFAS research lists low humidity tolerance among the reasons it is so popular. NC State prefers high humidity but agrees the plant will accept drier air. Tips that brown in a heated room or a drafty hallway are the cue to add a pebble tray or humidifier. Very damp, stagnant air has its own risk: Clemson links high humidity to powdery mildew.

Temperature

Cold is the real enemy. Clemson gives an ideal range of 68 to 80°F (20 to 27°C) and UF/IFAS Gardening Solutions 68 to 77°F (20 to 25°C); both allow brief dips to 55°F (13°C). UF/IFAS trials describe chilling injury as dark, greasy patches between the midrib and the leaf edge, appearing about two days after exposure. Unusually, the mature and older leaves suffer first while the youngest are largely spared. Tolerance varies enormously: 'Silver Queen' was damaged after 24 hours at 55°F, while 'Emerald Star', 'Stars' and 'Jewel of India' came through 35°F unharmed. Keep pots off cold windowsills in winter.

Fertilizer

Indoor aglaonemas need very little food. UF/IFAS recommends a 20-20-20 water-soluble fertilizer diluted to about 50 ppm nitrogen once a month, a weak solution compared with most label rates, and warns that overfeeding builds salts that burn leaf margins and tips. UF/IFAS also reports that most cultivars are prone to copper and other micronutrient deficiencies, which show as pale, dwarfed new leaves with serrated edges, so choose a fertilizer that includes micronutrients. Skip feeding in winter, following the Illinois Extension rule of fertilizing only between March and September.

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Repotting

Aglaonema grows slowly enough to stay in the same pot for years. Repot in spring or early summer when roots escape the drainage holes or the plant wilts between normal waterings, the signs Illinois uses. UF/IFAS Gardening Solutions points out a choice at that stage: move the whole plant to a larger pot, or divide the clump into two smaller plants and pot each one. Keep the crown at its old depth and water it in well.

• Roots grow through the drainage holes
• The plant wilts between normal waterings
• Suckers crowd the pot edge

Propagation

Division of basal shoots, or suckers, and stem cuttings are the standard methods. UF/IFAS notes that tissue culture has not been successful with this genus, so nurseries still root cuttings, ideally with four or five leaves each. Cultivars differ widely in how readily they sucker: some produce more than four basal shoots and are easy to split, while others produce none at all. When a stem becomes long and bare, Illinois suggests rooting the tip as a cutting or air layering it, and Clemson adds that the top of a leggy plant can simply be removed and rooted.

Methods: Division of basal shoots (suckers), Stem and tip cuttings, Air layering · Best season: spring to summer.

Common problems

NC State reports no serious disease or insect problems, but aphids, mealybugs, spider mites and scale do appear. Root rot follows overwatering or cold water. Two quirks are specific to aglaonema: a new leaf that emerges bent like a fishhook, which UF/IFAS ties to fluctuating light, water or temperature, and the dark, greasy blotches of chilling injury. When a spathe and spadix appear, UF/IFAS recommends removing them so the plant puts its energy into leaves rather than red berries.

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Is the Chinese evergreen toxic to cats and dogs?

The ASPCA lists the Chinese evergreen (Aglaonema modestum) as toxic to dogs, cats and horses. Its toxic principle is insoluble calcium oxalates, and the clinical signs are oral irritation, pain and swelling of the mouth, tongue and lips, excessive drooling, vomiting (not horses) and difficulty swallowing. The ASPCA entry names a single species, but NC State and UF/IFAS describe the same crystals across the genus, so treat every aglaonema as toxic. For people, NC State and UF/IFAS rate the severity as low, with possible skin irritation from the sap. Place it out of reach and call your veterinarian or the ASPCA Animal Poison Control Center at (888) 426-4435 if a pet chews it.

Check any other plant against the ASPCA lists →