Azalea plants are easy enough to grow if you have the right conditions. But, if just one condition is off, you may find your azaleas turning yellow.
Azaleas can turn yellow for reasons like :
- Shortage of Nitrogen in the soil
- Lack of water
- Soil is too alkaline to support azalea growth
- The soil drainage is poor
In some cases, a combination of these reasons could be causing the undesirable color change in your plants. But not to worry, we have a few solutions to solve your problem and return your azaleas back to health.
We have compiled the leading causes and appropriate solutions.
Nitrogen Deficient Soil
Not all soils happen to be rich in Nitrogen even though it is a vital nutrient required for plant growth. Most plants love nitrogen while other plants don’t flower best with its presence, an example is Lavender.
Want to grow lavender as well. Did you know they can turn color too? Find out the reasons for lavender turning yellow.
When it comes to azaleas, an excess or deficiency of nitrogen can cause repercussions. One such repercussion of low nitrogen levels in the soil can be the yellowing of leaves.
This is an evident sign that the soil used is very poor and not in accordance with an azalea plant’s needs.
Even though your soil may have been fertile at the time of planting, it won’t stay that way for long. These nutrients, especially nitrogen, will become depleted after some time. You will have to find a way to keep replenishing the nutrients in the soil.
Infertile soil can become a serious issue if you have many heavy-feeding plants growing in a small area. The rate of natural replenishment is low and you will have to go the extra mile to balance levels.
Solution
It has already been established that azaleas love nutrients and in particular, nitrogen. Your soil will eventually run out of this nutrient and you will have to provide it to them. This can be done in two ways:
1. Using nitrogen fertilizers to rectify the problem immediately
Mature azaleas won’t need artificial fertilizer unless the soil is sand-based or extremely nutrient-depleted.
But plants affected by yellowing will benefit from fertilizer. Give preference to nitrogen fertilizers that are water-soluble as they access roots faster.
If you are choosing this method, make sure to give the solution to the plants only in the growing season.
Apply it in spring or summer and avoid doing this in the fall at all costs! The reason being the fertilizer will stimulate new growth.
Unfortunately, this new growth is highly susceptible to frost. Hence providing it too close to winter will lead to extensive frost damage of new growth.
Although the plant is exhibiting yellowing, it is not in immediate danger of perishing. Waiting till the spring or summer season arrives is the best decision.
Besides, the plants will respond well and rapidly revert back to a healthy green color in a little over a week!
2. Adding high quantities of well-rotted compost that release nutrients (and nitrogen gradually)
You can also opt to mend your yellow azalea plants the traditional way. Replace any partially decomposed mulch with well-rotted compost. Use compost that has been well-rotted for close to a year.
A benefit of choosing this method is that there is no timeline. You can add the compost to the azaleas at any time of the year. It retains moisture during spring and summer while insulating the plants during winter.
Your yellow azaleas will be cured and will return back to their lush green color. However, this method is much slower than the fertilizer option.
But, if started early, this is a better way to permanently help soil regain its nutrient and nitrogen levels.
Lack of Water
Sudden yellowing of leaves is a bad and worrying sign for gardeners. It could be due to many reasons.
But, one of the leading reasons for azalea leaf yellowing is lack of water. One generous watering will not do it for azaleas.
These plants prefer moist soil and will be adversely affected by droughts and similar conditions. Regular watering is essential to keep these plants healthy and happy!
So, how do you know if the cause of azalea yellowing is simply not enough water?
Dip your fingers into the soil to feel the soil surrounding your plants. If the soil feels dry, you will know that drought is the reason for the yellowing of the plants.
Azalea plants will experience drought-like conditions in two instances:
- Insufficient watering or rainfall
- Extremely porous soil that isn’t holding any moisture
Solution
Since azaleas are water-loving plants, you must do your best to ensure the soil never completely dries out.
This can be done in two ways, adopting a generous watering routine and using soils that retain decent amounts of water.
At the hottest time of the year in warm climates, you must water your azaleas three times a week. Additionally to aid soil quality, add compost items like rotted manure or leaf matter to increase the soil’s water-holding capacity.
Soil with high organic matter content will still be porous but will hold adequate amounts of moisture. Thus, water will not accumulate in the soil and especially not at the roots.
Excessively wet soils can cause root rot, a condition that renders a plant’s roots ineffective. They will not be able to carry out their one purpose of transporting water and nutrients up to the whole plant.
Your plants will be compromised if affected by root rot!
Also, instead of concentrating moisture in the soil, you can concentrate it elsewhere. Add a 1-inch layer of mulch to the surface of the soil. This will help to retain moisture.
Overly Alkaline Soil
Another chemical characteristic of soil is its pH level. We cannot see any sign of soil pH and this is often overlooked. Especially when diagnosing why your azaleas are turning yellow.
Excessively alkaline soil can be the reason behind yellow azalea plants.
Azalea plants grow best in acidic soils that have a pH ranging between pH 4 and 6 (pH 5.5 is most ideal). Anything above pH 7 (neutral) is undesirable.
So when the pH goes above the desired readings, Azalea can turn yellow, a way of displaying their stress.
Azaleas may have difficulty absorbing nutrients from the soil when it has an overly alkaline pH. One particular nutrient it will be unable to absorb is Iron which is a vital nutrient it really requires for growth and functioning.
As a result, the lack of iron (iron deficiency) will cause a condition known as chlorosis. This condition is especially common among plants that are grown in soil that is not acidic enough to support the plants.
Although garden soils are predominantly acidic due to the presence of fallen plant foliage, it is not completely acidic yet! Only when the plant matter completely decomposes, will the soils be totally acidic.
But, not all gardens are blessed with semi-acidic soils! Other garden soils can have large amounts of lime which is incompatible with a range of acidic-soil-loving plants.
Solution
As a first step, try to determine the pH levels of your garden’s soil.
Look at the plants that are thriving most in your garden. Are there a few of the Roses, Daffodils, or Rhododendrons? If so then it is very likely that you do have acidic soil.
But even then, this is an estimate and you should not go by chance! There is an easy and cost-effective way to get a true reading.
Using a ready-made soil pH kit, you can get a real reading of your soil’s pH. Use this to decide the suitability of azaleas for your garden.
It is worthwhile to test several sites in your garden as pH values may vary. Installing a soil gauge is also another great idea to keep tabs on soil pH. As soils can change this characteristic regularly in short time periods.
If you have soil that is way too alkaline you can amend it.
Ways to make your garden soil more acidic:
- Incorporate Sphagnum peat into the soil
- Sulfur (in the form of granules or liquid)
- Acidic fertilizers
- 2 tablespoons of vinegar in a gallon of water (for potted Azalea plants)
Unfortunately, there are a few concerns with making garden soils acidic. Firstly, amending the soil is a very slow process that can even take months in some cases!
Thus, correcting soil pH must be done prior to planting your azalea plants. It cannot be done while growing.
Another big concern is that amended soil will not stay acidic for long. At a later time, the soil will revert back to its original pH level.
So, what should you do if the pH reverts back to its original alkaline pH reading?
Transplant your azaleas back to a pot. This way you can keep better control of the soil’s pH levels among other characteristics.
You can choose to transplant your plants at any time as long as it takes place during the growing season (summer).
Poor Water Drainage
Moist soil is vital for growing azalea plants and many other plants too. But, these plants have a level of tolerance as well.
Azaleas love moist soil but above a certain threshold, moisture will start to affect the plants negatively! Yellowing of leaves is one such sign of excess water.
Most often than not, it’s not that you are giving them too much water. The soil could be the culprit!
The amount of water in the soil is mostly determined by the draining capacity of the soil. Poor draining soils are most likely to accumulate water.
This mainly happens when soils have high clay concentrations or not enough sand/grit content. It could cause puddles to form or worse, accumulation of water at the roots where you can’t see.
Too much water in the soil can stop the roots from breathing and cause root rot. This renders the roots useless and poses a risk to the plant’s life.
Solution
To avoid surface water-logging, you can plant your azaleas on heaped mounds (raised beds). This will prevent them from sitting in soggy patches of soil.
Alternatively, you can amend the soil. You should decrease the amount of clay in the soil and increase the amount of sand or grit/gravel.
You can use these ratios as a marker:
- 20% clay
- 40% organic matter/silt
- 40% sand/gravel
If your soil contains these ratios, it should be well-draining and adequate enough for making your azalea plants healthy again.
Conclusion
Azaleas are beautiful colorful flowering plants that attract the eye, it is understandable why people would want to grow them. But, while growing them you may come into some difficulty when they start to turn yellow.
Causes of Azaleas turning yellow are:
- Shortage of Nitrogen in the soil
- Lack of water
- Soil is too alkaline to support azalea growth
- The soil drainage is poor
After narrowing down the reasons for azaleas turning yellow, you can focus on the solution.
Solution for yellowing of azaleas includes:
- Using water soluble fertilizers or using well-rotted compost only.
- Water the plants regularly or use water-retaining materials.
- Amend soil by adding Sulfur or Sphagnum peat to soil.
- Plant Azaleas on raised beds or improve porosity of soil by adding sand/gravel.
Are you struggling to grow Azaleas? Try French lavender instead! Read all about growing and caring for French Lavender.
FAQs
How do you stop yellowing leaves?
You can stop Azalea yellowing by making sure all conditions are ideal. This includes making sure soil is acidic, well-draining, and moist. Also, make sure there are enough nutrients and nitrogen in the soil.