My Moonflower Vine Stopped Growing

At Its Max

• The moonflower vine grows to an average maximum height of 15 feet and spread of 6 feet when grown as an annual, according to the Missouri Botanical Garden. In tropical zones, however, the vine can grow to over 70 feet long. If you are cultivating your moonflower as an annual, and it is the end of the growing season, the vine may have stopped growing because it has reached its maximum size. The same holds true for perennial moonflowers.

Too Much of a Good Thing

• This hardy plant is rarely seriously bothered by insect pests or diseases, according to the Missouri Botanical Garden, but adverse environmental conditions can limit its growth. If your moonflower vine is planted where water tends to collect, it may drown or develop edema. The leaves will wilt and change color, and you may notice that the soil remains squishy and wet for several hours after watering or rain. Drowning occurs when the soil is so saturated with water that the oxygen content declines. Edema occurs when the plant becomes waterlogged because water enters the plant faster than it evaporates. In both cases, the plant may become so stressed that it stops growing.

  If the plant is in a depression, and it isn't too large, move it to a raised location that drains better. Or, improve soil drainage by adding a layer of organic matter such as manure or shredded bark to the area round the vine. If the soil is heavy clay or sand, use at least 4 inches of organic matter. Spread it evenly around the vine, and then carefully work it into the top inch of soil while taking care not to damage the plant's roots.

Too Little of a Good Thing

• Moonflowers can also suffer from a lack of water, according to the University of Illinois Extension. The symptoms of a plant suffering from a lack of water can be the same as in a plant suffering from excess water. This is because in both cases, the roots are damaged. If your moonflower vine is wilting and the leaves are drying up and turning brown, check the soil. If it is hard and dry, your plant is probably not getting enough water, and it will start to decline as a result. To help the plant, be sure to water it enough so that the soil remains moist. The moonflower vine should get about an inch of water every week during dry periods.

Site and Cultivation Matter

• Keep your moonflower vine healthy and growing by caring for it properly. The moonflower vine needs at least partial sunlight, and full sun is even better. The hotter the weather, the faster it will grow and climb over fences, trellises and even trees. In fact, the plant is considered invasive in some areas, so choose its location with care. Give it plenty of room to spread out, and plant it far away from other desirable plants so that it does not smother them by climbing up and over them.