Aglaonema Siam Aurora Care: Soil & How to Keep It Red

Aglaonema Siam Aurora care centers on three non-negotiables: bright indirect light between 400 and 800 foot-candles, a peat-based potting mix with 20 percent perlite, and a strict dry-top-inch watering rule. When you meet these thresholds, the plant keeps its signature pink-to-red midrib variegation and pushes out 6 to 10 new leaves per year. Miss the light level, and the red fades to muddy green within 4 to 6 weeks.

This cultivar of Aglaonema commutatum is sold under names like Red Aglaonema and Red Chinese Evergreen. It is compact, slow-growing, and tolerant of average home conditions, which makes it popular among indoor gardeners. Yet its color is conditional. The following guide gives exact metrics for light, water, soil, fertilizer, and propagation so you can keep the red bright rather than hoping for the best.

Aglaonema Siam Aurora needs bright indirect light at 400 to 800 foot-candles, temperatures between 65°F and 80°F, and watering only when the top 1 to 2 inches of soil dry out. Use a peat-based mix with 20% perlite, feed with a 3-1-2 NPK liquid at half strength monthly during spring and summer, and propagate by division for the highest success rate.

What Is Aglaonema Siam Aurora and Where Does It Come From?

Aglaonema Siam Aurora is a cultivar of Aglaonema commutatum, a herbaceous perennial in the Araceae family. It reaches a maximum height of 1.2 meters and spreads to 0.6 meters. The lanceolate leaves display green margins with bright pink to red midribs and veins. It originates from the tropical understories of Southeast Asia.

According to NParks Flora & Fauna Web, the plant grows as an erect herb with a rhizomatous root system. The leaves are simple, alternate, and measure 15 to 30 cm long. Unlike the solid-green parent species, Siam Aurora has been selected for anthocyanin expression in the leaf veins, a trait that requires more light to maintain than the plain green forms. If you are new to the genus, start with our broader Chinese Evergreen care hub before fine-tuning for this cultivar.

How Much Light Does Aglaonema Siam Aurora Need to Stay Red?

Siam Aurora requires 400 to 800 foot-candles (4,300 to 8,600 lux) of bright, indirect light to maintain its red variegation. Direct sun scorches leaves within hours. Light below 200 foot-candles causes the red pigment to fade to green and slows growth to fewer than 4 new leaves per year.

The red color comes from anthocyanin pigments in the leaf veins. According to The Spruce, variegated Aglaonema cultivars need significantly more light than solid-green forms because the non-green tissue cannot photosynthesize. Without adequate light, the plant reverts to chlorophyll-dominant green.

Use the following distance guide for placement. A light meter app on your phone can approximate foot-candles. If the reading falls below 200 fc for more than 3 days, expect color loss within 2 weeks. Rotate the pot a quarter turn every 7 days to prevent lopsided growth.

What Is the Best Soil Mix for Aglaonema Siam Aurora?

Use a peat-based potting mix amended with 20 percent perlite and 10 percent orchid bark for aeration. The pH should sit between 5.5 and 6.5. Aroid-specific mixes or standard houseplant soil with added drainage both work, but avoid unamended garden soil which compacts and suffocates roots.

Clemson Extension recommends a well-drained, peat-based potting medium for all Aglaonema species. The peat retains moisture without staying soggy, while perlite creates air pockets that prevent anaerobic conditions.

Do not use cactus mix straight from the bag; it drains too fast and leaves the fine roots desiccated. Do not use garden soil, which harbors pathogens and hardens into a brick within months. For a deeper breakdown of amendments, see our guide to the best aroid soil mix.

How Often Should You Water Aglaonema Siam Aurora?

Water when the top 1 to 2 inches of soil feel dry to the touch, typically every 7 to 10 days during active growth and every 14 to 21 days in winter dormancy. Overwatering is the primary cause of yellow leaves and root rot in this species.

Clemson Extension identifies overwatering as the most common cause of decline in Aglaonema. The rhizomatous root system stores some moisture, so the plant tolerates brief dry spells better than it tolerates wet feet. Use the finger test: insert your index finger to the second knuckle. If the soil clings to your skin and feels cool, wait 3 more days. If it feels dry and crumbly, water thoroughly until excess drains from the bottom.

Signs of overwatering include yellowing lower leaves, a musty smell from the pot, and blackened, mushy roots. Signs of underwatering include brown, crispy leaf tips and drooping stems that recover slowly after watering. In winter, metabolic rate falls by 40 to 60 percent. Cut watering frequency in half during these months.

Use room-temperature water. Cold water shocks the roots and can cause leaf spotting. Siam Aurora shows tip burn when fluoride levels exceed 1 ppm over time.

What Temperature and Humidity Does Aglaonema Siam Aurora Need?

Maintain temperatures between 65°F and 80°F (18°C and 27°C). Avoid sustained exposure below 55°F (13°C), which causes chilling injury and leaf drop. Average household humidity of 40 percent to 60 percent is sufficient; misting is unnecessary and can promote fungal issues on the foliage.

Clemson Extension lists the ideal temperature range as 65°F to 80°F. Nighttime temperatures can drop to 60°F without harm, but prolonged exposure below 55°F triggers chilling injury. Symptoms include water-soaked lesions on leaves that later turn brown, and sudden defoliation of the lower canopy. Keep the plant away from air-conditioning vents, drafty entryways, and single-pane windows in winter.

Humidity requirements are modest. Most homes sit at 40 to 50 percent relative humidity, which satisfies the plant. If your indoor air drops below 30 percent in heated winter months, you may see increased spider mite activity or brown leaf margins. A pebble tray or small humidifier placed nearby is more effective than misting, which wets the leaf surface and encourages bacterial leaf spot.

How Do You Fertilize Aglaonema Siam Aurora for Best Growth?

Apply a 3-1-2 NPK liquid fertilizer at half strength every 4 weeks during spring and summer. A balanced 10-10-10 or 20-20-20 formula also works but provides excess phosphorus that variegated foliage does not need. Cease fertilization in fall and winter when light and growth slow.

Nitrogen drives cell division and chlorophyll production, which supports the leaf structure that displays the red variegation. The 3-1-2 ratio mirrors the actual nutrient uptake pattern of tropical foliage plants better than a balanced 1-1-1 blend.

Dilute the label recommendation by 50 percent. Apply to moist soil, never to dry roots, to avoid fertilizer burn. Flush the pot with plain water every 8 to 12 weeks to leach accumulated salts. Signs of nitrogen deficiency include uniform pale green color across the entire leaf. Signs of excess fertilizer include brown, crispy leaf margins and a white salt crust on the soil surface.

How Do You Propagate Aglaonema Siam Aurora Successfully?

Division is the most reliable method: remove the plant from its pot, separate the root ball into sections with at least 3 stems and attached roots, and replant immediately. Stem cuttings in soil root in 4 to 6 weeks; water-rooted cuttings often fail during the transition to soil.

According to NC State Extension, Aglaonema propagates readily by division because each stem cluster carries its own adventitious roots. Spring is the optimal season, coinciding with the start of active growth.

1. Water the plant 24 hours before dividing. Hydrated roots are flexible and less prone to breakage.
2. Remove the plant from its pot and gently tease away the old soil to expose the root ball.
3. Identify natural divisions where 3 or more stems emerge from a shared rhizome section.
4. Cut through the rhizome with a sterile knife or pruners. Each section must have roots attached.
5. Pot each division in fresh mix at the same depth as the original plant.
6. Water lightly and place in bright indirect light. Maintain soil moisture but not saturation for the first 4 weeks.

Stem cuttings are an alternative but less reliable for beginners. Cut a 4- to 6-inch stem section just below a node, remove the lower leaves, and insert it into moist potting mix. Enclose the pot in a clear plastic bag to maintain humidity. Rooting typically takes 4 to 6 weeks at 75°F. Water rooting is possible but risky; the water-formed roots are brittle and often rot when transferred to soil. For this reason, soil rooting is the recommended method for home growers.

Why Is My Aglaonema Siam Aurora Losing Its Red Color?

Color fade is almost always caused by insufficient light below 200 foot-candles. Other causes include nitrogen deficiency, natural aging of older leaves, and extreme temperature stress. The red pigment anthocyanin requires energy to synthesize; low light prioritizes chlorophyll production over pigment expression.

According to The Spruce, variegated Aglaonema cultivars revert to green more quickly than solid-green forms turn pale, because the variegation is metabolically expensive. If you catch the fade within 2 weeks of onset, moving the plant to brighter light can restore color on the next 2 to 3 leaves. Leaves that have already turned green will not regain red pigment.

Is Aglaonema Siam Aurora Safe for Pets?

No. Aglaonema Siam Aurora is toxic to cats, dogs, and horses. All parts contain insoluble calcium oxalate crystals that cause oral irritation, excessive drooling, vomiting, and difficulty swallowing upon ingestion. Keep the plant out of reach of pets and small children.

The ASPCA lists Chinese Evergreen (Aglaonema spp.) as toxic to cats, dogs, and horses. The mechanism involves insoluble calcium oxalate crystals shaped like needles, called raphides. When a pet chews the leaf tissue, these crystals embed in the oral mucosa, triggering immediate pain, swelling, and hypersalivation.

If you suspect ingestion, rinse the animal’s mouth with water and contact your veterinarian or the ASPCA Animal Poison Control Center. Symptoms usually resolve within 24 to 48 hours, but airway obstruction from severe swelling requires emergency care.

If you share your home with curious cats, place Siam Aurora on a high shelf or in a hanging planter beyond jumping reach. For non-toxic alternatives, browse our cat-safe plants guide or visit The Infirmary for toxicity resources.

What Pests and Diseases Attack Aglaonema Siam Aurora?

Spider mites, mealybugs, scale, and aphids are the most common pests. Root rot from overwatering is the dominant disease. Inspect leaf axils and undersides weekly; treat infestations with insecticidal soap or neem oil at the first sign.

NC State Extension notes that Aglaonema is generally pest-resistant indoors, but stressed plants attract opportunists.

Root rot (Pythium, Phytophthora) manifests as yellowing leaves, wilting despite wet soil, and black, mushy roots with a foul odor. The primary trigger is soil that stays wet for more than 5 days. If you catch it early, unpot the plant, trim all black roots with sterile scissors, soak the remaining healthy roots in a 1:3 solution of 3% hydrogen peroxide and water for 3 minutes, and repot in fresh, dry mix. Hold water for 7 days after repotting.

How Do You Prune and Maintain Aglaonema Siam Aurora?

Remove yellow or brown leaves at the base with sterile scissors. Prune leggy stems in spring to just above a node to encourage bushier growth. Wipe leaves monthly with a damp cloth to remove dust that blocks light absorption and harbors pests.

Sterilize your pruners with 70% isopropyl alcohol before and after each cut. This prevents transferring pathogens from one plant to another. Cut yellow leaves at the soil line; never tear them, as this leaves a wound that invites infection.

If the plant becomes tall and sparse, cut the main stem 1/4 inch above a visible node in early spring. The node will activate within 2 to 4 weeks, producing one or two new lateral shoots. You can root the removed top section as a stem cutting if it has at least 2 nodes.

Dust accumulation reduces photosynthetic efficiency by blocking light. Wipe both leaf surfaces monthly with a soft cloth dampened in lukewarm water. Do not use leaf shine products; they clog stomata and create a sticky residue that traps dust.

Repot every 2 to 3 years, or when roots circle the bottom of the pot. Choose a container only 1 inch larger in diameter than the current one. Too much soil volume relative to root mass leads to chronic overwatering.

Pro Tip: Use a Moisture Meter
The fastest way to kill Siam Aurora is to water on a calendar schedule. Insert a moisture probe 2 inches deep. If the dial reads 3 or below on a 1-to-10 scale, water thoroughly. If it reads 4 or above, wait. This simple tool eliminates the guesswork that causes 80% of root rot cases in Aglaonema.

Frequently Asked Questions

Can Aglaonema Siam Aurora grow in low light?

Yes, but the red variegation fades to green. It survives in 100 to 200 foot-candles, yet growth slows to fewer than 4 leaves per year and the color reverts within 4 to 6 weeks. For best results, maintain 400 to 800 foot-candles.

How fast does Aglaonema Siam Aurora grow?

It is a slow to moderate grower, producing 6 to 10 leaves per year under optimal light and fertilizer. In low light or winter dormancy, growth may stall entirely for 3 to 4 months.

Why are the leaves on my Aglaonema Siam Aurora turning yellow?

Yellow lower leaves usually signal overwatering. Check that the top 1 to 2 inches of soil dry before the next watering. If multiple leaves yellow rapidly, unpot the plant and inspect for black, mushy roots indicating root rot.

Can I propagate Aglaonema Siam Aurora in water?

You can, but soil rooting is more reliable. Water-rooted cuttings often develop brittle roots that rot after transplant. For best results, root stem cuttings directly in moist potting mix inside a humidity tent.

Is Aglaonema Siam Aurora the same as Red Aglaonema?

Yes. Siam Aurora is the cultivar name, while Red Aglaonema and Red Chinese Evergreen are common marketing names. All refer to Aglaonema commutatum ‘Siam Aurora’.

How do I make my Aglaonema Siam Aurora more red?

Increase light to 400 to 800 foot-candles of bright, indirect exposure. Ensure you are feeding with a 3-1-2 NPK fertilizer at half strength during the growing season. Red pigment (anthocyanin) requires energy and nitrogen to synthesize; low light and nutrient deficiency both suppress color.

Now that you have exact thresholds for light, water, soil, and fertilizer, you can keep your Siam Aurora crimson instead of watching it dull to olive. For more tropical foliage guides, browse The Lab. If you notice yellow leaves or suspect pests, head to The Infirmary for diagnosis protocols. You can also compare this cultivar to the Silver Bay variety for a different color palette.