5 Reasons Your Indoor Azalea Is Dying and How To Fix It

These beloved woody perennial shrubs bring their colorful charm indoors through florist-potted varieties. The forced blooms in vibrant shades emerge as many other plants are resting. If your indoor azalea shows signs of stress and decline, join gardening expert Katherine Rowe in exploring a few primary causes and how to restore its vigor.

Written by Katherine Rowe Horticulture review by Sarah Jay Last updated: December 27, 2024 | 5 min read

Pink double flowers with layered petals and deep green, oval-shaped leaves in a compact arrangement.

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Potted azaleas dot nursery and market shelves around holiday time, with dense foliage and bright blooms in red, white, pink, purple, and salmon. They give weeks of color and bring cheer to chilly days.

We know azaleas as the lovely evergreen shrubs that bring a sweep of blooms in shaded springtime gardens. It’s often the mini-potted florist selections this time of year that draw us with abundant flowers in portable pots, perfectly suited to give or receive.

So, how to balance the shift in the woodland evergreen from commercial greenhouse to winter home? Some signs of stress as the potted selections acclimate are not uncommon. If your indoor azalea is ailing, a few key cultural changes may restore it to full health.

Indoor Azalea Overview

A potted plant with clusters of white flowers and dense, glossy green leaves in a white ceramic pot on a wooden surface. — Potted florist types come with the intention of enjoying them as petite indoor specimens.

Florist azaleas represent only two cultivated East Asian species and their hybrids in the large Rhododendron genus (R. simsii and R. obtusum). Azaleas naturally grow as understory shrubs in mild-climate woodlands with rich, acidic soils with a spring and early summer bloom time.

Potted florist types come with the intention of enjoying them as petite indoor specimens. While sometimes short-lived, they can grow and produce under optimal conditions beyond their initial bloom (usually around holiday time). Growers force them to bloom during the winter by controlling temperatures and growth to initiate the perfect timing.

Rhododendron obtusum can move to the garden in spring. With shelter from winter winds and mulch protection, it can survive outdoors in USDA zones 7-10. Commonly called Hiryu, this azalea reaches three to eight feet tall in nature.

Rhododendron simsii are frost-sensitive and perennialize in zones 8-10. They’ll enjoy summer outdoors in pots to move back inside in cold winter climates. The formosa azalea is popular in warm regions for its large frame and robust bloom clusters. The evergreens reach five to ten feet tall, depending on the variety. These, and their hybrids, are the most common florist types.

Reblooming indoors for either species can be a challenge. Their overall health and ability to thrive depends on the variety and type of treatment from the grower and through the supply chain down to our homes. If you opt to hold onto your azalea, it may take a year or two to resume flowering after forced situations.

Temperature Swings

Three potted plants, two with white flowers and the other with pink flowers, placed on a windowsill. Both have dense, green leaves. — Place pots in a cool room or near a window for lower temperatures.

Azaleas perform best in cooler temperatures, but chilly blasts or prolonged cold exposure cause leaf and stem damage. Temperatures near 40°F (4°C) result in bud loss, while near-freezing conditions can damage tissues. Alternatively, hot and dry conditions cause stress and deterioration.

Temperature fluctuations are common as we move plants this time of year, even from the nursery to the car or the car to home. The resulting stress from drastic sweeps can take a toll. To avoid sudden chill or heat, keep pots away from drafts. Heating and air vents, open doors, space heaters, and fireplaces cause sweeping fluctuations that may inhibit growth.

Ideal temperatures for indoor azaleas are around 50-68°F (10-20°C) in winter. Warmer situations – 75°F (24°C) or higher – limit bud development or cause young buds to fall. Place pots in a cool room or near a window for lower temperatures. Below 50°F (10°C) risks slow development and bud loss.

A cool environment also helps blooms hold longer. In warm situations, they’ll open and drop more quickly.

Low Humidity

A flowering plant with pink blooms and glossy green leaves, placed indoors among other green plants. — To increase surrounding humidity, group them with other houseplants for a little microclimate.

Humidity is another important consideration as we heat our homes in winter. Indoor azaleas prefer medium to high levels of air moisture. Humidity around 50% works well, and while this is average in many households, winter can vary.

To increase surrounding humidity, group them with other houseplants for a little microclimate. Or, place the container on a tray filled with pebbles and water. The pot should rest on the pebbles above the water to avoid absorption.

Water Inconsistencies

A bright pink single flower with ruffled petals surrounded by textured green leaves, growing on a thin stem. — When this dries between watering, you’ll notice quick wilting.

Florist Rhododendron spp. often come in a peat moss potting media. When this dries between watering, you’ll notice quick wilting. Azaleas have fine surface roots sensitive to drying out. It’s best to keep soils evenly moist and well-draining.

Underwatering

Water deeply until it runs through the pot’s drainage holes.

If your specimen is in a peat-based mix with significant drying, rehydrate it with a good soak. Submerge the pot in a sink or bucket of tepid water for 15 minutes. Let it drain thoroughly post-soak. Continue with a regimen for even moisture, watering when the media begins to dry on the surface. Azaleas don’t do well in pots when dry and don’t like to dry out between waterings.

Watering frequency is usually about once a week, depending on the growing environment. Rainwater or bottled water is best. Tap water in hard water systems may contain alkalinity in the form of dissolved sodium bicarbonate, toxic to azaleas.

Water deeply until it runs through the pot’s drainage holes. Don’t leave a filled tray to linger beneath the container long after a watering session.

Root Rot

A close-up of a plant's roots affected by a fungus, showing discolored, decaying roots and dark soil. — Rot causes the roots to turn brown and mushy; as they decay, they can’t function to support growth.

Opposite underwatering is creating overly soggy soils. Overwatering damages roots and leads to their inability to uptake water and nutrients necessary for flowering. A common fungal disease to look out for is root rot. Overwatering creates saturated conditions that promote its development. Rot causes the roots to turn brown and mushy; as they decay, they can’t function to support growth.

Plants in overly soggy media with poor airflow may show yellowing and wilting leaves. Slip plants out of their pots to check the roots and clip off those that are brown or damaged. Replant the azalea in fresh media and water thoroughly. If caught early, you may see rebounding growth.

Too Much Light Or Not Enough

A potted plant with clusters of bright pink flowers and dark green leaves, placed in a sunlit room. — Keep the containers out of direct sunlight to prevent burning the tender leaves and petals.

Indoor azaleas need bright, indirect light to thrive. A good situation is near an east-facing window or, in cold climates, a south-facing winter exposure. Ample natural light, about four to six hours, supports the energy needed to grow and flower.

Keep the containers out of direct sunlight to prevent burning the tender leaves and petals. Filter direct rays with a curtain for dappled light.

Iron Deficiency

A gloved person holding a handful of pine bark chips used as mulch for soil. — Organically rich soils with good drainage (including pine bark chips or horticultural sand) are a good foundation.

Acid-loving azaleas are sensitive to increased alkalinity, which results in toxicity. Certain potting materials, hard tap water, or overfertilizing can cause chlorosis. Alkaline soils have high pH levels (above 7.5). The sweet spot for azaleas is an acidity between 4.5 and 6.0. Adjusting soil pH makes iron available.

Alkaline soils block access to nutrients, leading to yellowing leaves, a lack of vigor, and eventual decline. Organically rich soils with good drainage (including pine bark chips or horticultural sand) are a good foundation.

Avoid overfeeding potted specimens. If you’ve just received the beauty in bloom, it won’t need fertilizer until spring, if at all. If you’re nursing an existing azalea, stick with a formula for acid-loving plants (rhododendrons, hollies, camellias). Again, hold off until new growth emerges in spring. A tailored acidic formula provides nitrogen in the beneficial form of ammonium nitrate over common nitrates. Garden sulfur and iron chelates are other amendments to correct deficiencies.