mandevilla yellow leaves

(Question)

Last year I lost a mandevilla when the leaves turned yellow. This year the same thing is happening and I really want to “save” it. It is on a balcony with lots of sun. We water judiciously. Pansies in the same large pot are doing well. I thought maybe the soil wasn’t right so we changed it out. I read that the ph should be 5.5-6.5. Where can I get a ph soil test done. I am losing 5 or 6 leaves a day!! I want to solve this problem asap. Please help

(Answer)

It sounds as if you may be watering your mandevilla too much. Blooming mandevillas need moist soil that drains well. Too much water can choke the roots so they don’t feed the plant adequately and cause the leaves to turn yellow. Conversely, too little water can be deadly, starting with yellow leaves that turn brown and drop off the plant. Check the soil around the base of the mandevilla regularly and if it’s dry at least 1 inch below the surface, it needs water.  Here is a site for more information on mandevillas: https://homeguides.sfgate.com/mandevilla-leaves-turn-yellow-67344.html