Newly purchased Mandevilla vines are dropping blooms and leaves are starting to yellow. Am watering every other day and giving Miracle Gro weekly. Temps here in the Phoenix are are in the mid 90's. Is this too hot for full sun now?
Certified GKH Gardening Expert
There are a number of reasons why the leaves may turn yellow. One might be overwatering. Too much water causes yellowing of the leaves and mandevilla do not like overly wet feet. Check the soil around your plant to see if it's too moist and, of so, allow it to dry some. Mandevilla favor humid conditions. If your plant is exposed to the sun, the soil may be too hot (the most likely case for yours in addition to over watering). Try misting/spraying the leaves with water in the mornings and keep the soil moist (NOT wet).
Another possibility could be too little water. If this is the case, the yellow leaves would be curling up as well. Mealy bugs can occasionally affect these plants, causing them to become weak and leading to yellow foliage. Finally, plant stress due to a change in location, temp., etc. can lead to yellow leaves.