I have a mature Southern magnolia tree with large roots rising out of the ground. What can I plant under the tree that will survive?
Rising up to 60 feet tall with a canopy often reaching 50 feet wide, Southern magnolias (Magnolia grandiflora) are one of the more majestic trees that grace our gardens. Because of their attractive evergreen foliage, sweet smelling blooms and interesting berries these giants are a treasure if you have room to grow them.
As the name implies, Southern magnolias are best suited for warm climates. They are only reliably cold hardy to zone 7 where winter temperatures do not drop below 10 degrees F on a consistent basis. However they can be grown in zone 6 and some varieties will survive as far north as zone 5. They thrive in full sun, but will tolerate partial shade. Plant them in well-drained, humus rich, moist and slightly acidic soil and they will be a relatively carefree addition to your garden for many years to come.
The root system on a Southern magnolia is fairly extensive and shallow, resulting in the problem that you are experiencing where the roots rise to the soil surface. Couple this with the low, dense canopy and year round dropping of leaves and you have an area where it is very difficult to grow anything.
The first thing to understand about the situation is the relationship between the roots and the canopy. The canopy serves as a protection for the roots from sunlight and helps them to remain cool and moist. So you really don’t want to remove the lower branches. Also mature trees don’t heal quickly from pruning and can develop a wood disease.
If the tree is young you can plant a shade loving ground cover, such as liriope, under the canopy, but with a mature tree such as yours it is best not to dig around the roots.
Your best option for tidying up the area is to apply a thin layer of mulch, no thicker than 3 inches, under the canopy. Keep the mulch at least 2 feet away from the trunk of the tree.
If space allows you can use the shady shelter of the branches as a relaxing retreat from the summer sun. A comfortable chair, good book and glass of lemonade can quickly turn this otherwise dead space into a secluded spot that will bring back fond memories of childhood tree houses while staying securely on the ground!