Mandevilla prefers consistently moist soil while it’s actively growing. In warm climates, it may require water three times per week during spring, summer and fall. Container-grown vines dry out quickly, so watch moisture closely. Reduce watering to once per week during winter as the plant enters dormancy.Click to see full answer. Accordingly, how do you care for a potted mandevilla?Once indoors, place your mandevilla vine in a place where it will get bright, indirect light. Water the plant when the soil is dry to the touch. In the spring, when the temperatures are consistently above 50 F. (10 C.), remove any dead leaves and move your mandevilla plant back outside to enjoy for another summer.Beside above, how do you keep a Mandevilla over the winter? Winterizing Mandevillas If you’re short on bright light or space, you can bring the mandevilla indoors and store it in a dormant state. Put the plant in the sink and drench the soil thoroughly to wash out pests that may be lurking in the potting mix, then cut it back to about 10 inches. In this way, why are my Mandevilla leaves turning yellow and falling off? Blooming mandevillas need moist soil that drains well enough to prevent standing water. Too much water can choke the roots so they don’t feed the plant adequately. This can 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.How long do Mandevillas last?Yes, you’ll usually see the first mandevilla flowers in early summer and the mandevilla bloom period lasts until the first frost in autumn. This beautiful vine is tougher than it looks, but it is killed by frost in USDA plant hardiness zones 8 and 9.