There are 240 varieties of Magnolias, but there are probably only about 30 you will find around the Grapevine area. Southern Magnolias are planted for their shade and their evergreen foliage. There are deciduous Magnolias that loose their leaves in the winter and have large, usually purple or pink flowers. There are some new yellow blooming Magnolias but they are a rare find in this area.
Magnolias generally have few fatal issues. Their bark is thin, so they are prone to winter freeze damage and bark cracking. Scale often attack the leaves and stems. The scale are not fatal, but they produce honeydew which bring black sooty mold growth, which makes the tree unsightly. Another pest that likes to attack Magnolias is Sapsuckers. Sapsuckers are like woodpeckers that drill into the bark making a line of holes in the tree. When Sapsucker damage is extensive the water flow to the tree is reduced weakening it. Also each hole is an open place for insects and disease so attack. Occasionally leaf miners will harbor in leaves, but this is usually minor damage and only damages the leaves.
Magnolias are attacked by many diseases but the hot dry North Texas weather keeps most of the diseases from becoming an issue. The main Magnolia disease seen in this area is Bacterial Leaf Spot. You will see spots on the leaves, usually these spots are silver inside. You will probably see a yellow halo around the spots.
Magnolias are one of those species that require certain micro-nutrients in larger amounts than other species. Iron and Zinc are two of the most widely lacking micro-nutrients for magnolias in this area. Zinc is needed for blooms while Iron is needed to prevent yellowing of the leaves. Magnolias prefer acidic soils. They will grow in alkaline soils like Grapevine soils tend to be but they do not get large and grow very slowly.
In addition to general soil amendment and mulching, yearly fertilization of Magnolias in Grapevine is also recommended. You can add some peat moss in with the original soil you took out of the planting hole when you plant a Magnolia. The peat will lower the pH, making the soil more acidic like the tree prefers.
Before you plant a Magnolia tree, make sure you have enough room. Southern Magnolias need at least one hundred and eighty square feet to grow, maturing at up to 90 feet tall and 40 feet wide.
It takes 3 to 10 years for magnolias to bloom. When they do, flowers can measure 12 to 14 inches across.
A good variety for Grapevine would be Little Gem Magnolia. Little Gem produces large, fragrant, white flowers that reach a width of 8 inches. It will produce flowers for 6 months every year. Little Gem leaves are leathery with a deep, glossy green color on top and a bronze brown, fuzzy underside. Mature height is about 20-25 feet tall and grows about 1 foot per year.
If your Magnolia has insect of disease issues, we suggest you call Green Top Lawn Care and talk to their Horticulturist on staff about starting a program of treatment.