Once established in your garden, magnolia trees and shrubs require little maintenance as they develop nicely shaped habits and are usually pest and disease free. Early-spring flowering species, those that bloom before leaves emerge, often have blossoms killed by late frosts. Plant such varieties in a sheltered location out of cold and drying winds and not in low elevations where cold air settles. Magnolias are long-lived woody plants.
The easiest way to ensure a healthy magnolia is to pay attention to the soil in which it grows. Four key soil conditions need to be maintained: moist, well-drained, organic-rich and acidic. For the most part all magnolias prosper in these conditions. The soil should be consistently and evenly moist but well-drained so roots do not rest in soggy or flooded conditions. Lots of compost and humus in and atop the soil helps retain moisture and provide nutrients, conditions that magnolia roots love. Lastly, always make sure magnolias grow in acid soil (pH below 7.0), which prevents nutrient deficiencies most often seen as yellowed leaves. The use of an organic mulch that degrades to create acidic conditions is ideal, such as pine bark, pine straw, coffee grounds or oak leaf mold. Irrigate magnolia trees deeply but infrequently during extended droughts to prevent premature leaf drop or tip die-back.
Magnolia trees' roots are shallow, leading to their susceptibility to harm from droughts, hot summer temperatures and soil compaction. Again, the use of an organic mulch over the root zone diminishes these issues since the mulch helps retain moisture, shades and cools the soil and prevents lawn equipment, "cow path" pedestrian traffic or parking vehicles from compacting soil next to the tree. Make the mulch layer about 3 to 4 inches deep and extend it out 3 to 4 feet beyond the farthest reaches of the outermost branches. The physical outline or bed of mulch creates a visual barrier that shouldn't be casually crossed as nonchalantly as a lawn, bare soil area or walkway. This eliminates the need for a lawnmower or weed-trimmer getting remotely close to the tree trunk and possibly damaging it.
Focus only on pruning away dead or rare diseased branches from a magnolia. Overall, magnolias grow with an even, pleasant habit but occasionally an errant branch needs trimming or removal. Consider waiting until early summer or late fall after leaf drop to prune magnolias to diminish the amount of sap that bleeds from the pruning wounds, which occurs heavily in springtime. Be aware than tip pruning after midsummer removes immature flower buds that will become flowers for next spring. To harvest a magnolia flower in spring for a bouquet, make the pruning cut on-fourth inch above a lower branch junction or dormant bud. Use a sharp pruners, too; breaking twigs off creates a jagged or torn spot for insects or diseases to enter the plant.