“Think of magnolias as you might fashion - there’s a size, shape, style, and color suited to the decor of just about any garden, even the smallest,” says Judie Evrard Brower of Tesselaar Plants, an international plant research company. “Some can even be container-grown.” And don’t think for a moment that they’re fragile. “Magnolias are easy to care for and disease-resistant,” Brower says. They’re also versatile; they can grow as a hedge or be trained to climb up a lattice against a wall.
Here in central Texas, caring for magnolias can take a small amount of effort. Although the species will grow here, even in rocky soils, their needs really should be assessed based on each individual site. Our soils vary widely. Some soils such as those of Dripping Springs and Wimberley are very rocky and riddled with shallow limestone and very little good soil (except near the river where the soil can be great!). The rocky soils are very high pH (alkaline) soils. Other areas such as downtown and East Austin, and Northwest Hills have much deeper soils. Areas by Lake Austin have flat alluvial and extremely fertile soils from years of silting and produce magnificent specimens. East of IH35 in Kyle and Buda the soils are a heavy black clay.
Having cared for magnolias in all these areas, I find that most of the problems magnolias have are soil related. Additionally, compaction and lack of mulch often exacerbate already poor soil conditions. Lack of water, in addition to one or more of these factors, is also a limiting factor in the summer months especially. Soil amendment helps, add finished compost as a top dressing around but not touching the trunk out several feet or better yet, out to the edge of the canopy, this will help with water retention and will lower the pH a bit. Also mulch to 3 inches (max) and keep your trees well watered during the hot summer months and you will find your magnolia is no longer thinning or stunted.
Magnolias are one of those species that, in addition to their macro-nutrient requirements (N,P,K,S,Ca,Mg), they also 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, for example, is needed for the blooms. Iron is needed to prevent interveinal chlorosis (yellowing between the leaf veins). Additionally, magnolias thrive in low pH, acidic soils. Although they will grow in alkaline rocky soils, they do not get large and grow very slowly, and are of course more prone to nutrient deficiencies, the compost really helps with this.
In addition to general soil amendment and mulching, yearly fertilization is also helpful. When I apply a general slow-release, organic, granular fertilizer I will sometimes add a magnolia ‘micro’ mix to add missing micro-nutrients. Though more and more I find that adding the compost really does the trick. I have brought many magnolias back in the central Texas area over several years, and find that they will thrive if given the right minerals, mulch, water and soil conditions, including lowering the Ph. If you have a stressed or stunted magnolia follow the guidelines above and its problems will be gone in no time at all.
One of the best-known dwarfs is Magnolia "Little Gem." Although this cultivar can grow to twenty feet, it does so very slowly. Little Gem is an evergreen, hardy in zones 5 through 9. The upright tree produces white flowers with a delicious fragrance. Little Gem can be grown successfully in containers if you prune it back to control its size and spread. In the landscape, Little Gem can get as wide as ten feet without pruning and tolerates almost any kind of soil. It prefers full sun to light shade. This magnolia will produce blooms while still very young.
Chances are, once established any variety of magnolia will outlive any of us, and isn’t that a nice thing to pass on to the next generation!