Morning glories are vine plants that will grow to heights of 7 feet or more depending on if the vine is growing on a fence or trellis. Plants normally grow with little care, but there may come a time when the morning glory leaves start to turn yellow. If this happens, it can be the result of one or more problems pertaining to dry or wet conditions, sunlight and temperatures.
Plants that are too dry or wet develop yellowing leaves. Morning glories grow vigorously without any additional water if the area receives at least 1 inch of water per week. During dry spells that last for longer than one week, water the plants with 1 inch of water. If the location where the plants are growing has standing water, the plant roots will start to rot, causing the leaves to yellow.
Morning glories need sunlight in the morning and afternoon to grow and flower. If the plants don’t receive enough sunlight, the leaves will start to yellow and die. Before planting the seeds, you need to choose a location with at least six hours of sun, which includes the morning sun.
It is not uncommon for leaves to turn yellow on morning glory plants as the temperatures cool down at night. Although not all the leaves will turn yellow at the same time, temperatures will affect how the leaves green up or turn yellow and die. If the leaves are turning yellow in September or later, it has to do with the temperatures that plant has at night. A light frost will cause the leaves to turn yellow, but some leaves will stay green longer.
Morning glories don’t require any fertilizer to grow and flower, but if you do add fertilizer, it is done when the plant starts growing. Fertilizing after the plant starts to mature can cause the leaves to turn yellow because of overfertilizing. These plants will grow in any type of soil as long as it has good drainage.