Q.Why Are My Allamanda Leaves Yellowing?
Hello, I recently bought a medium sized Allamanda plant (Allamanda blanchetii) from a local nursery and re-potted that after a couple of days in a container. Since, the plant was in a plastic bag with soil, I ensured that I did not disturb the roots/remove any soil that was with the plant. I ensured that it got settled with the new environment and potting medium for a couple of more days. I have been watering the plant daily at noon (around 2, 3 or 4 pm). The temperature in my area now is pretty high (30 to 35 degrees Celsius) and gets gets hotter and dry at noon. The position of the plant was such that it gets only direct afternoon sun for about 2 to 3 hours. The potting mix that I used was 90% garden soil & 10% Vermicompost (note that it was intact in it’s own soil from the nursery). Since then, I have added NPK 20:20:20 once and Epsom salt (diluted with water) after a week or so. Yesterday, I added micro-nutrients powder (1/4 of a pinch) with 1L water and gave that in the soil. I also did not mist water on it’s leaves until now but when I slowly observed that the leaves are yellowing, I assumed that it must be the intense heat/scorching sunlight and hence, I sprayed water on it’s leaves yesterday. I have observed a slight increase in the yellowing of the leaves. Since yesterday, I have moved that to a little shader area. I am attaching a picture of the plant for your reference. In case, you are unable to view the pic, I am also providing a link to the image as a back-up. (https://ibb.co/J3LkRss) As you can see about 3 or 4 leaves are slowing turning yellow. I need some urgent advise on what can be done to prevent all the leaves from turning yellow and eventually the plant dying. I don’t think there is any pest problem as I can hardly see any insect/bug. Is this due to heat, watering (over/under) or over fertilisation?? Your early advise would be much appreciated. Thanks!
Certified GKH Gardening Expert
This is, very much, a case of overwatering and drastic overfertilization.
I would plant it into a light potting mix with very little fertilizer for the first few months. Too much fertilizer will halt new root formation. As long as your climate remains warm, year round, then planting outside shouldn't be too much of an issue.
In most regions, this is used as an indoor plant, strictly. They can be a little easier to care for in container, and where you can control humidity and temperature.
As far as the light requirement of the plant- The brighter the better. They prefer full sun.
Here is an article that will give you information on the strict environments that these plants require: