Magnolias (Magnolia spp.) are classic plants in Southern gardens, but can grow in almost any climate in U.S. Department of Agriculture plant hardiness zones 3 through 12, depending on the species and cultivar. Members of the magnolia family, with more than 200 species, vary in size, shape and flowering capabilities. They have enough common characteristics you can determine the health of a young magnolia.
Unless your magnolia plant flowered profusely in previous years, you really can't use flowers to determine whether a young magnolia tree is healthy. Some magnolias, like "Little Gem" large-flowered magnolia (Magnolia grandiflora "Little Gem"), which grows in USDA zones 7 through 9, begin flowering when they're 1 or 2 years old. Other varieties, such as the bigleaf magnolia (Magnolia macrophylla), which grows in USDA zones 5b through 8b, can take 15 or more years to bloom for the first time. If you have one of the varieties that matures slowly, you cannot use flowers to determine the health of the young plant. If you own one of the early-maturing varieties, look for large, fragrant flowers, free from pests and diseases, in early spring or summer.
Some magnolias naturally drop their leaves over the winter, while others stay green all year. If you have a young evergreen magnolia that drops a few leaves occasionally, do not worry as this is natural. If it drops a significant portion of its leaves, something may be wrong. When on the tree, the leaves will tell you if your plant is under stress. In hot areas with full sun, you may see brown spots on the leaves indicating sunburn. In some situations, you may see fungal leaf spots or mildew. Healthy leaves will have a rich, green color with no spots or blemishes.
Many species of magnolia have a slow to moderate growth rate, adding only 1 to 2 feet per year, so if your plant does not grow quickly, do not worry too much. If you notice stunted growth this year compared to last -- with your tree producing smaller-than-normal leaves and only adding a few inches -- your young magnolia may have something wrong. It's possible the plant only needs a dose of fertilizer and some extra water during the hottest part of the summer, but it could also be showing you that it does not like its current location.
Branches and Trunk
Although most of the problems with pests and diseases show up on the leaves of magnolias, you can also check the bark of the tree for signs of problems. Look for scale insects in the form of small bumps on twigs -- their presence, or the presence of any pests, indicates your tree is not in the best of health. Look also for any wounds or large broken branches, as these may create an entry point for future diseases. If you see decaying, rotting wood or sunken spots indicating canker, these also signal ill health. A healthy, young magnolia will have unblemished, or nearly unblemished wood everywhere.