Alyssum plants are green but the foliage is rarely seen when these plants are blooming beautifully. Though, if your Alyssum starts turning yellow you would look for reasons and solutions to overcome this.
Reasons for Alyssum turning yellow includes poorly draining soil. inadequate soil nutrients, wet and damp weather, too much sun, excessive shade, inefficient care after transplantation, diseases, and pests.
Reasons Why Your Alyssum Is Turning Yellow
There is a multitude of reasons that are behind your alyssum turning yellow. They range from poor soil drainage, lack of nutrients, unsuitable climate, excess moisture, adverse weather conditions, and lack of care.
Let us look at them in detail below.
1) Poorly Draining Soil
Alyssum plants are usually easy-go-lucky when it comes to soil characteristics. But, there is just one characteristic they are extremely particular about, and that is soil drainage.
While soil fertility is not crucial, poorly draining soil will cause alyssum to turn yellow and eventually die. The plants do not thrive in soils heavy with clay or boggy soils.
Remember that the alyssum originates from coastal areas of the Mediterranean, where they grow on the beaches and sand dunes. Here there is more sand and grit than soil. So even if your soil mix has some sand and gravel, it helps with the drainage.
Alternatively, you can use sand as your base to mix in small amounts of organic material to hold just enough water. Testing your soil beforehand will be helpful in avoiding problems later on with excessively wet soil.
2) Inadequate Soil Nutrients
Most often than not it is infertile soil that lacks essential nutrients for the health of the plant that causes the alyssum to turn yellow. Not all soils can boast of a balance of nutrients.
Other plants in the vicinity of the alyssum could be more demanding and could be depriving the alyssum of nutrients. Alyssums are not very greedy plants but having the bare minimum of nutrients is mandatory for them to survive in a garden setting.
Giving your plants a balanced slow-release fertilizer at the time of planting will benefit the plant. Thereafter, at the beginning of the flowering season, your alyssum will get a flowering boost with an N-P-K fertilizer that’s equally present (10-10-10).
During this fertilizing session, a water-soluble fertilizer will help the plant bloom better than a plant without fertilizer.
We recommend J R Peters Jacks Classic No.4 10-30-20 Blossom Booster Fertilizer for assisting Alyssum to bloom.
3) Wet And Damp Weather
Excess rain and moisture without a ray of sunshine can cause the leaves to turn yellow, and possibly the whole plant!
The plant gets over-saturated with water and is unable to take in oxygen. The plant has very limited options in this case and may possibly die if no assistance is offered!
If a spell of particularly bad weather is coming, consciously try to protect your alyssum. Especially if you know the weather is going to last and the plants won’t dry out on their own.
Make sure your alyssum has excellent drainage, starting with the soil. Before planting, prepare your bed with a good drainage mix.
Next, premeditate ways to protect the plant. Bring the pots indoors or else build a protective shield to keep as much water out.
4) Too Much Sun
Most alyssum plants do exceptionally well in direct sun, particularly if you live in a mild to a slightly cold area. However, if you live in a region that has extreme heat and even drought in the summers, you could find your alyssum struggling to survive.
The heat burns the plant and giving extra water may not even revitalize your alyssum plants. They could be sunburnt and may not recover.
Try to give your plants some form of shelter from the hot sun. Try going to your local plant nursery to see what kind of shade cloth they have, they can also advise you on how best to use it.
Placing a shade cloth over them that is held up by poles is best if you have lots of alyssum in one area.
Another option is to transplant your alyssum plant to a less sunny area or somewhere where it will avoid the most severe sun exposure in the shade.
If your alyssum plants are in containers, move them to a shady area, like under a tree, or a shady part of the patio.
6) Excessive Shade
Too much shade also prevents the plant and soil from drying out after being watered. Plus it can also limit the amount of photosynthesis the plant can carry out. This increasingly damp environment will then go on to encourage pests and diseases to infest the plants.
All in all, too much shade is not advisable. Alyssum plants should get more sun than shade ideally.
Exposing the plants to the sun for at least 6 to 8 hours a day will be most beneficial, and it will keep your plant healthy. The plants and the soil will be able to dry out as desired as this will help to ward off certain diseases.
7) Ineffective Care After Transplanting
Leaves can turn yellow due to inadequate care during and after transplanting. Rough handling of seedlings when transplanting, or being left in the open without moisture, affects the plants.
After transplanting the seedlings might need extra water to root, and shade is necessary so the heat does not evaporate the water.
NOTE- Alyssum plants are more vulnerable to transplant shock than most other plants.
Shade the seedlings, do not leave them to dry out, at any stage of the transplanting process. Keep them out of the soil for the shortest possible time. To make this happen, keep the new site ready before uprooting your alyssum plant.
Provide fertile soil, or even a rooting hormone initially.
8) Diseases – Root Rot And Wilt
There are many diseases that may indicate their presence due to the yellowing leaves. Some may be due to poor conditions while others undergo induction about by fungus or virus.
Here the root rots due to an excess of water, which causes the leaves to turn yellow. This occurs initially after which the foliage withers away and the plant dies. This condition is not just common in alyssum but in other water intolerant plants as well.
Curing the plant is difficult or even impossible. So, it is better to concentrate on preventing the condition. Avoid watering the plant on its crown, water stagnates there and causes rot.
Overwatering is not advisable, especially in heavy soils that do not drain well. Get rid of all plant material with infection to stop it from spreading to healthy plant matter.
9) Fungal Infections
Infections due to fungus usually manifest when conditions are wet or humid with poor air circulation. Fungal spores are already present in the air, soil, and perhaps water as well. Hence, avoiding the conditions in which they thrive is crucial for the health of your alyssum and other ornamental plants.
Increase spacing between plants to ensure enough air passes through and carries off excess water in the air. Also, keep tabs on watering habits. Don’t water plants if the ground hasn’t dried from the last watering session.
Where there are flowers and plants full of sap, pests usually ensue! It’s usually the same suspects, aphids which most often attract ants as well. These and any other insects that specifically prefer alyssum plants.
Apart from this, another insect that affects alyssum is the Aster Leafhopper. This insect feeds on the sap of the plant but this is not the worst part. It can feed on infected material and transfer the infection from a diseased plant to a healthy one.
The disease in question is called Aster Yellows, a disease caused by phytoplasma bacterium. This condition results in the pale coloring of flowers and stunting of foliage and even flowers.
Hose down plants to reduce aphid numbers, thereafter, applying Neem Oil, or insecticidal soap should do it. Because ants are drawn to aphids as a food source, controlling aphids will control ants as well.
As for Aster Leafhoppers, applying Carbaryl helps to control their numbers. Otherwise, to avoid transmission of Aster Yellows, immediately dispose of infected material. Try to limit the growth of plants that can be infected with this disease.
Don’t be alarmed at the first signs of your alyssum turning yellow. Instead, focus your energy on pinpointing the exact reason for it turning yellow. Once this is done, you will be able to work on the best way to solve it.
Through the years I have found that the most common reasons for my alyssum turning yellow are:
- Poorly draining soil
- Inadequate soil nutrients
- Wet and damp weather
- Too much sun
- Excessive shade
- Inefficient care after transplantation
Only once the cause is found and corrected, will your alyssum start to grow well and green again. Use the solutions we have provided to help your alyssum to health.
Yes, it is possible to overwater alyssum plants. Wilting shows excess and a lack of water. You must observe which one of the two it is.
Usually pruning your alyssum plant by a ⅓ rd will help it to reshoot by refocusing energy. Also, if your plant and its soil are too wet, let the plant dry out and change the soil out. Offer the plant a bit of fertilizer while replanting.