Botanical name: Rhododendron simsii
Rhododendron simsii commonly called Indian Azalea is a popular flowering plant that will add a splash of color when in bloom but lasts a short period indoors.
It is only displayed indoors when in bloom after which it is taken outdoors until the next bloom or discarded altogether.
In warm climates, Indian Azalea will thrive outdoors. But in the cold regions, it can only be grown as a container plant for a patio or a deck which is brought inside in winter.
Indian Azalea is a popular plant in India where it is grown as a garden plant and the flowers are used for religious purposes. It is hardy in USDA Zones 7-9.
They are evergreen plants which bear glossy, green, egg-shaped leaves which are hairy along the leaf margins.
Rhododendron simsii grows best in bright light away from direct sunlight, cool temperatures, moderate humidity and acidic, consistently moist, well-drained soils.
Rhododendron simsii can grow to a height of 5-6 ft and 5-6 ft wide. Most of the plants grown nowadays as Indian Azalea are cultivars and hybrids of Rhododendron simsii which rarely exceed 2-4 ft.
The blooms are terminal meaning the entire plant blooms at one time which makes a colorful display. They are a profusion of shades of pink, red, white, peach, lavender or bi-colors.
The large, funnel-shaped flowers occur in clusters of 2-5 and are about 2 in. wide. They may be single or double and may sometimes have ruffled petals. Blooming occurs in spring and may last upto 3-4 weeks.
Rhododendron simsii is native to East Asia in China, India and Taiwan.
Indian Azalea is toxic to humans and pets as indicated by ASPCA. If ingested it can cause a burning sensation in the mouth, drooling, vomiting, diarrhea and lethargy. Keep Azaleas from the reach of children and pets.
Azalea Plants are readily available online. Buy Azalea Plants online from Etsy.
Rhododendron simsii thrives in bright light away from direct sunlight, cool and moderately humid conditions and consistently moist, well-drained soils that are rich in organic matter coupled with regular feeding during the growing season.
Container grown Indian Azalea requires repotting only when it has outgrown its current pot as it blooms best when pot-bound. Cutting back of the stems is necessary after flowering to encourage more flowering. Keep reading for more on these growing conditions and how to achieve them.
Indian Azalea grows best in bright light conditions but away from direct sunlight as it can scorch the leaves. If the light is too low, the plant will become leggy and will not bloom.
Outdoors, situate the plant in a shaded spot like under the trees, under the house eaves and other shaded places.
Indoors, place the Rhododendron simsii next to a brightly lit window but do not allow the sun rays to fall on the leaves.
Where the natural lighting is not adequate, consider investing in a grow light as enough light is necessary to prolong the life of the plant.
Regularly rotate the pot to ensure that the plant receives light on all sides for even growth.
Water Indian Azalea liberally during the growing season while allowing the top 1-2 in. of soil to dry out between waterings to keep the soil consistently moist.
For container-grown plants, do not allow the plant to sit in soggy soil. Ensure that the container has adequate drainage holes and that the soil is well-drained.
Discard any excess water from the catch plate to prevent the soil from gettting soggy. Soggy soil can lead to root-rot and death of the plant.
Avoid watering the plant with too cold water as it can lead to shock of this tropical plant which can result in leaf and flowerbud drop.
Occasionally water the Indian Azalea by the immersion method as it ensures that the soil is thoroughly wetted.
Use chlorine-free water as Rhododendron simsii is sensitive to chlorine and other chemicals dissolved in water which can result in yellow leaves.
Decrease watering during the cold period as growth is minimal at this time to keep the soil slightly moist but do not allow the soil to dry out completely to avoid leaf drop.
Indian Azalea prefers cool to average temperatures within the range of 12-180C and a minimum of 100C in the cold season (winter). Very high temperatures will result in flowerbud drop.
Container-grown plants should be brought indoors when the temperatures begin to drop in winter and taken back outdoors in spring when the threat of frost has passed as Indian Azalea is not frost hardy.
To keep the soil warm in the cold season, apply a 2-3 in. mulch of dry vegetation on the soil surface but take care not to let the mulch come into contact with the stem to prevent rotting.
Indoors, keep Rhododendron simsii away from cold and hot drafts to avoid sudden changes in temperatures which can cause leaf drop, flowerbud drop and reduced growth.
Position it in a cool place and maintain a moderate room humidity. If the indoor air is too dry, set the pot on a wet pebble tray or use a cool mist humidifier to raise humidity and keep the plant thriving.
Do not mist the leaves as excessive moisture on the foliage can encourage fungal disease infestations. Also, ensure that there is good air circulation.
Rhododendron simsii is an acid-loving plant. To keep it happy, feed it with a fertilizer formulated for acid-loving plants every 2-3 weeks during the growing season.
Withhold feeding during the cold season as growth is reduced at this time. Do not feed an Indian Azalea that is in flower as it can shorten the flowering period.
The best soil for Indian Azalea should be free-draining, rich in organic matter and acidic at a PH of 4.5 to 6.0. Use a soil PH meter to confirm it is within this range. If the PH is not within the recommended range, it should be ammended.
To increase PH (if it is too acidic), add lime to the soil. To decrease PH (if it is too alkaline), add soil sulphur. Allow a 2 weeks period for the soil to correct the PH.
Check out this quality potting mix on Amazon for container grown plants.
Repot a container grown Indian Azalea during the growing season only when the plant is extremely pot-bound as it blooms more when root-bound.
When you notice any of the following, it is time to repot your Rhododendron simsii; roots growing through the drainage holes, the soil dry out faster than before, wilting and leaf drop.
Do not repot a plant that is in flower as the repotting shock can shorten the flowering period.
Use a pot 1 size larger than the current one and one that has a drainage hole to prevent the soil from getting soggy as it can lead to root-rot and eventual death of the plant.
Place a layer of gravel in the bottom of the pot to enhance drainage and prevent the soil from blocking the drainage holes. Fill the pot a third way with the recommended soil.
Take out the plant from its pot, loosen the soil around the roots and shake off excess soil. Inspect the roots and cut away dead roots. To keep the plant small, cut off a third of the roots.
Position the plant in the center of the pot, spread out the roots and fill the pot with the soil. Lightly firm the soil around the plant.
Water the soil liberally until water comes out through the drainage holes and place the set up in a warm, well-lit place.
Prune Indian Azalea yearly after blooming by cutting back the stems to the desired height. This will encourage growth of new stem tips from which the flowers grow which means the plant will bloom even more.
Remove dead flowers and leaves to maintain the plant neat and tidy as well as reduce pest and disease infestations.
To encourage branching and the growth of a bushy compact plant, pinch off the growing tips regularly to attain the shape and size you desire.
Rhododendron simsii propagation can be done from stem cuttings but they take long to root and do not stay true to type. It is preferable to buy a plant from the breeders.
Indian Azalea (Rhododendron simsii) problems indoors include leaf drop, yellow leaves, flowerbud drop, short flowering, shrivelled leaves, pests and diseases among others. Keep reading for more on these problems and how to fix them.
Short flowering period in Indian Azalea grown indoors is caused by hot dry indoor air which drastically reduces the air humidity.
Keep the plant away from hot air drafts like ovens, hot surfaces and set the pot on a wet pebble tray or use a cool mist humidifier to raise humidity.
The second cause of a shortened flowering season in Indian Azalea is exposure of the plant to the hot direct sunlight.
The third reason for a very short flowering period in Rhododendron simsii is underwatering.
Indian Azalea requires moist soil at all times. Wet the soil deeply and maintain it consistently moist during the growing season.
Cut down on watering during the cold season but never allow the soil to dry out completely.
Yellow leaves in Indian Azalea are due to watering the plant with hard water; chlorinated water is not good for this plant.
Azaleas are acid loving plants and therefore should not be watered with hard water or chorinated water. Use distilled or rain water only to water this plant.
One cause of flower bud drop in Indian Azalea grown indoors is too dry air (low humidity). Dry air will cause the flowerbuds to shrivel, turn brown and drop.
Protect the plant from drafts and set the pot on a wet pebble tray to raise humidity. Check out these techniques on how to raise humidity for houseplants.
The second reason for flowerbud drop in Indian Azalea is underwatering. Keep the soil consistently moist during the growing season.
The third cause of flowerbud drop in Indian Azalea is too little light. Ensure that the plant receives bright, indirect light to promote blooming.
Yellow leaves with green veins in Indian Azalea is a sign of a nutrient deficiency due to high alkalinity in the soil.
Azaleas grow best in an acidic soil. Feed the plant with a fertilizer formulated for acid-loving plants every 2-3 weeks during the growing season.
Leaf drop in Indian Azalea is due to incorrect watering; either underwatering or overwatering. The plant thrives in consistently moist soil but not soggy soil.
Maintain the soil moist at all times during the growing season. Avoid soggy soil by ensuring that the pot has a drainage hole and that the soil is well-drained.
Lessen watering in the cold season as growth is minimal at this time but do not let the soil dry out completely.
Shrivelled leaves in Indian Azalea are caused by underwatering or allowing the soil to dry out between waterings for a prolonged period of time.
The soil needs to be kept consistently moist during the growing season and slightly moist in the cold period but do not allow the soil to dry out completely.
One common disease in Indian Azalea is powdery mildew which causes the new leaves to curl, become pale, then brown and die. Discard the plant as it will not recover for this disease.
The other common disease in Indian Azalea is root-rot which is prevelant in soggy soil brought about by poor soil drainage.
Ensure that the soil is free-draining and the pot for container plants has a drainage hole to prevent the soil from getting soggy. Read on how to treat root-rot disease.
The common pests in Indian Azalea are spider mites, scale insects and nematodes. Regularly inspect the plant for these pests and take timely control measures.