- Azaleas require moist soil. If the soil dries out the plant will wilt and the leaves will curl. Water azaleas as frequently as required to ensure the soil is moist (but not saturated).
- Water potted azaleas with rainwater not tap water. Rainwater contributes to the acidic conditions that azaleas prefer. Tap water can be pH neutral or alkaline.
- Water logged soil leads to root rot. Pots without proper drainage in the base or the use of drip trays cause the soil to be saturated. Signs of root rot include yellow/brown leaves with a wilting appearance.
- Pots and containers have a limited capacity for nutrients hence the requirement for fertilizer. A lack of fertile or enriched soil can stunt the growth of the azalea.
- Too much direct sun can burn tender azalea leaves and cause drought whereas not enough light will limit growth and the number of flowers.
- Indoor potted azaleas are sensitive to high temperatures and draughts. Fluctuating temperatures can cause leaf drop and drought.
- Azaleas require acidic potting soil (pH 4-6) to be able to access nutrients. In less acidic soils, neutral or even alkaline conditions, azalea leaves often turn yellow and the plant does not live long.
1. Water Frequently (with Rainwater) to Keep the Soil Moist or Risk Drought
Azaleas require the soil to be consistently moist at all times (without the soil being saturated).
Azaleas have a naturally shallow root system and therefore they’re usually one of the first plants to show signs of drought (wilting appearance with leafs curling up).
Indoor and outdoor potted azaleas require watering far more frequently then those planted in garden boarders.
Water azaleas with a generous soak so that there is a trickle emerging from the base of the pot. This way you will know that the water has infiltrated the soil effectively.
At the hottest times of year I recommend watering the azalea at least twice per week. Although you should water azaleas as frequently as required to keep the soil moist.
Beware of forced air or radiators heating up indoor azaleas and intense sun on outdoor azaleas will heat up the pots quickly and increase soil evaporation as these are common causes of drought.
To learn more best practices and how to tell when you azalea requires watering, read my article on how much and how often to water azaleas.
2. Use Rain Water not Tap Water
Azaleas require acidic soil conditions (pH 4-6) so that the roots can absorb nutrients. It is always better to water you azalea with rain water as rain tends to be more acidic and will promote the acidic conditions in which azaleas thrive.
Whereas tap water is usually around pH neutral 7 or even an alkaline pH (any value above pH 7).
It will not phase the azalea to occasionally be watered with tap water, particularly if the soil has been prepared properly, however consistent watering of azaleas in pots can increase the soil pH and make it more difficult for the azalea to access the nutrient that it requires.
The symptoms of azaleas that are in soil that is not at the right level of acidity are yellow leaves, often with stunted growth. If this has happened to your azalea read my article on azaleas with yellow leaves for the solution.
3. Water Logged Soil: Drip Trays or Pots Without Drainage
Azaleas require their potting soil to be moist yet well draining, so that excess water can escape out the drainage holes in the base of the pot.
Always choose a pot for you azaleas that has drainage holes in the base, otherwise the soil becomes saturated, which will result in the disease root rot (Phytophthora).
Yellow/brown leaves with a wilting appearance are signs of stress due to over watering or soil that is saturated rather then moist.
A layer of gravel at the base of the pot is often useful to keep the drainage holes free from compacted soil so that water can easily escape from the pot.
If this has happened to your azalea, transplant the azalea into a new pot with good drainage and replace the soil. Visibly inspect the roots of the azalea and snip off any roots that are yellow and have turned rotten. Replanting the azalea in new soil will give your plant the best chance to survive.
Avoid this mistake: One of the most common mistakes for indoor potted azaleas is to use a drip tray underneath the pot to catch the excess water so it does not cause a mess.
The problem is that this will prevent water from escaping the pot and effectively drown the roots which cause azalea death from root rot.
The solution is to move your pot outside temporarily for say half an hour so that the water can drain away and return the pot indoors afterwards.
4. Lack of Fertility in Potting Soil
Potted azaleas are more likely to suffer from a lack of nutrients in the soil then those planted in the garden due to the limited soil capacity of a pot. Also there pots do not have the beneficial soil ecosystem that works to increase nutrient availability.
Without nutrients added to the soil, azaleas produce fewer blooms and growth can be spindly.
The solution is to use an azalea fertilizer in the spring. Specialised azalea fertilizers contain the optimal balance of nutrients and contribute to the acidic soil conditions that the azalea roots require to uptake nutrients.
Slow release granules, provide the azalea with plant food over the course of the growing season to increase growth and blooms. If you suspect you azalea is suffering with a lack of nutrients, wait till the spring to add the fertilizer. If fertilizer is added in the summer then it may stimulate the growth of foliage at the expense of flowers.
Re-potting the azalea every few years will prevent the roots from becoming pot bound and provide nutrient rich soil. Re pot azaleas either every four years or when they become pot bound to ensure a healthy plant.
5. Not Enough (or too much) Light
Azaleas grow and bloom to their best when in partial shade. Full sun will burn their tender leaves (particularly in arid climates) and cause drought whereas full shade will result in fewer flowers and less foliage growth and a spindly appearance.
The key to healthy azaleas is to find the optimal balance between light and shade in your climate.
Azaleas grow well in dappled light under a sparse tree canopy as this mimics their natural habitat. However 4 hours of morning sun followed by shade in the afternoon often provides a balance so that the azalea flowers and yet is still protected from harsh midday sun.
With potted outdoor plants you can move your azalea around easily to find the right balance of light.
Indoor plants with fewer flower should be moved to a sunny window that allows for some direct sun for about 4 hours per day.
Consider that azaleas require the soil to be moist so more sunlight increase soil evaporation and transpiration from the azaleas leaves so you will need to increase the frequency of watering to prevent drought.
6. High Indoor Temperatures (too near draught or heat source)
Another common mistake with indoor azaleas is to locate them in areas of the house that are too hot, often because of radiators or forced air or even draughts from air con.
This often leads to the classic symptoms of drought such as a wilting foliage with the leaves curling up and flowers that droop. Really high temperatures can also cause leaf drop, particularly if the temperature fluctuates significantly, from a relatively cool temperature during the day to higher temperatures at night.
Even if you water frequently, the increase in transpiration from the leaves due to the dry air can cause the plant stress.
Ideally locate the azalea out the way of significant sources of heat or air currents and make sure that you water the azalea as frequently as is required so that the soil is moist (but not water logged).
7. Acidic Soil for Azaleas in Pots
Azaleas require an acidic soil of pH 4-6 for the roots to be able to access all the nutrients they require from the soil. If the soil pH is closer to pH 7 or alkaline then the azalea leaves will likely turn yellow, with stunted growth and the plant will die.
It is essential that you ensure you potting soil is acidic before planting for the plant to be healthy and to bloom in the Spring.
Azaleas that are planted in soil that is not within the optimal range of acidity can be saved if they are re-potted into soil that is more suitable, although the azalea may take a season or so to recover.
The easiest way to ascertain the soils pH is with a soil gauge which is accurately measures the soils pH and can be used for both potting and garden soil so that you can plant with confidence. Best of all they are available for a great price on amazon.
To ensure that your soil is at the right pH for azaleas I would recommend planting with ericaceous (acidic) potting soil which is available online and in garden stores. Read my guide for more information on the optimal soil mix for indoor and outdoor potted azaleas.
- Drought is one of the biggest risks for potted azaleas as the roots are relatively shallow and they require the potting soil to be consistently moist but not saturated. Outdoor pots can dry put quickly in the sun and indoor pots dry out because of sources of heat in the house.
- Water with rainwater if possible as rain water is acidic (azaleas require acidic soil) and tap water tends to be pH neutral (7) or even alkaline.
- Azaleas often suffer from root rot when they are in pots without suitable drainage holes in the base or drip trays catch the water and the soil becomes saturated. Root rot symptoms are drooping foliage with yellow/brown leaves.
- Growth can become stunted or the plant may produce fewer blooms due to a lack of fertility in the soil. Add slow release fertilizer in the spring with a specialised azalea plant food which contains the right balance of nutrients.
- Azaleas prefer partial shade. Without enough light an azalea will exhibit poor growth and fewer flowers but with too much direct sun azalea leaves will turn brown, flowers will wilt quickly and the risk of drought increases due to soil evaporation and transpiration from the leaves. Morning sun followed by shade from intense midday sun and the afternoon is ideal for most climates, as is dappled light from a tree canopy.
- Fluctuating room temperatures are a threat to azaleas as rooms with too high heat can cause leaf drop and drought. Keep indoor azaleas out the way of air currents and away from radiators.
- Azaleas require acidic potting soil of pH 4-6. If the soil is closer to pH 7, neutral or even alkaline then the azaleas roots will not be able to absorb the nutrients the plant requires. Signs of stress include yellow leaves, stunted growth and fewer flowers. Amend the soil with ericaceous compost or peat moss (both acidic) before planting azaleas in pots to maintain the right level of acidity for a healthy azalea.