Magnolia tripetala is a small-to-medium flowering tree native to the eastern United States that is known for its stunning white blooms and enormous glossy green leaves. Sometimes known as the umbrella magnolia, the magnolia tripetala is a perfect specimen tree in landscapes that do not always get the most sun. Here’s everything you need to know about caring for this stunning tree.
I. Appearance and Characteristics
Magnolia tripetala, commonly called umbrella magnolia or simply umbrella-tree, is a deciduous tree native to the eastern United States in the Appalachian Mountains, the Ozarks, and the Ouachita Mountains. The name “umbrella tree” derives from the fact that the large leaves are clustered at the tips of the branches forming an umbrella-shaped structure.
Umbrella magnolias have large shiny leaves 30–50 cm long, spreading from stout stems. In a natural setting the umbrella magnolia can grow 15 m tall. The flowers are large, appear in the spring, malodorous, 15–25 cm diameter, with six to nine creamy-white tepals and a large red style, which later develops into a red fruit (an aril) 10 cm long, containing several red seeds. These trees are attractive and easy to grow. The leaves turn yellow in the autumn. The leaves are clustered at the tip of the stem with very short internodes. The tree has reddish cone-shaped fruit, is shade tolerant, has shallow spreading roots, and is pollinated by beetles.
Leaves on M. tripetala trees are alternate, simple, and oblong. They are a dark green on top and pale green underneath the leaves. These leaves are clustered at the ends of branches, giving them the appearance of an umbrella. The leaves and arrangement resemble their relative M. macrophylla. These trees are naturally in rich and moist woods, along slopes, streams and ravines. The bark is thin and gray, mostly smooth and can have raised lenticels. Trees typically grow from single stems, though multiple stems are not uncommon. The flowers on M. tripetala have been described to have unpleasant smells but are not toxic to organisms. These trees grow at a moderate rate during the spring season.
Magnolia tripetala in cultivation can produce low viability pollen (9.4-31.7%). Actual seed productivity of the M. tripetala is less than their potential productivity. However, M. tripetala are characterized by a high seed germination rates, up to 94%. Optimal seed germination conditions for M. tripetala are protected ground or a greenhouse and stratification at 4 °C for 30 days.
II. How to Grow and Care
Sunlight
Magnolia tripetala finds its home at the edge of wooded areas in the sun or shade of larger canopy trees. Ideally, you want to mimic its natural conditions in your landscape by providing those same conditions. Giving your tree either full sun or partial shade will ensure it is in the right environment to thrive and produce its most abundant blooms.
Temperature and Humidity
Magnolia tripetala is not particularly frost-hardy and not extremely fond of hot, humid temperatures, making it the perfect tree for temperate landscapes along the eastern United States. To achieve the longest blooming season, avoid planting in an area with high winds and avoid harsh temperature extremes, and you will have a happy tree. Keeping it with the recommended USDA zones 5-8 will ensure it thrives and provides you with beautiful blooms.
Watering
Newly planted trees must be watered weekly for the first two years during the spring and summer until roots are established. Water deeply erring on the side of longer watering than more frequent, shorter watering. A long saturating soak is better than five quick spritzes.
If planting your magnolia tripetala in a dry area, supplemental watering will be needed to keep your tree thriving. While it does not tolerate dry soil, it will not tolerate wet soil, so keeping on top of a watering regime is necessary for your tree’s health. Mature trees will appreciate abundant soaking every week during summer, especially in dry weather.
Soil
Umbrella tree prefers acidic soils, which is important to consider if you are gardening in alkaline soil such as clay or chalk. Add a layer of peat when planting your umbrella tree to help raise acidity levels. In areas where soil remains wet, particularly during the winter months, this is no reason to worry: umbrella tree can happily cope with compact, rich soil.
Fertilizing
Organic fertilizer should be applied to the base of the plant in spring. At this time of year, your umbrella tree will just be starting to develop leaves and will want extra nitrogen to help with their production. This gives plants the energy to bloom a little later in the season. Therefore, a nitrogen-rich fertilizer such as dried-blood meal is recommended.
Later in the year, and particularly if your region has had heavy rain over the growing season, umbrella tree benefit from a lighter feed of fertilizer to help return vital nutrients into the ground. A fertilizer with potassium, such as potash, is suitable at this time of year and can be applied during fall before the tree becomes dormant over the winter.
Pruning
The natural form of the magnolia tripetala doesn’t require a lot of pruning, but doing some light pruning will remove suckers and eliminate unwanted main trunks from forming. You should also prune annually to remove dead, dying, and damaged branches.
Sucker removal should be done annually in the spring when new growth appears, and anti-growth products can be applied to deter new sucker growth.
Trunk removal should be done only when a trunk is young and when you are still determining form; if the main trunk has already established lateral branches it may not be too late to remove, but consider removing the lateral branches first and then the trunk, remembering that only 1/3 of the tree’s live material should be removed at a time.
The best time to determine the tree’s form is in the first few years as it establishes itself; at this point, the job can often still be done with loppers rather than a saw and will stress the tree much less than it would then if it was done later in the tree’s life.
Propagation
Propagating the magnolia tripetala is a great way to get another specimen for your landscape while removing some of those unsightly suckers growing at the base of your tree. There are several ways to propagate your magnolia tripetala, but taking cuttings is by far the easiest way, which also allows you to save those suckers that you’d otherwise just throw away. You’ll need garden clippers, a sharp sterilized knife, a pointy object rooting hormone, potting mix, and some pots. Here’s how to propagate magnolia tripleta:
- Trim a sucker about 1/8 inch in diameter and off the tree, then find an area with some nice new growth and cut about 5 to 7 inches off of the sucker.
- Tear the leaves from the bottom of the cutting, around 2/3 down, and scrape away the bark exposing the fleshy part of the sucker.
- Cut the end of the sucker at a 45° angle. This is now your new cutting.
- Make a hole in your potting mix for the cutting.
- Following the product’s instructions, dip your cutting in your rooting hormone and let soak, then insert into the hole in the potting mix.
- Keep the potting mix moist and in a cool, indirectly lit area. Check the bottom of the pots around the three-month point to see if roots have established.
- When roots have been established, transplant the plants into larger individual pots and let roots establish in those pots for one to three months.
Pests and Diseases
Luckily the magnolia tripetala is known to be easy to take care of and, most importantly, low maintenance. While it suffers from a few issues, most are relatively benign and easily fixed with just a few easy maintenance tasks.
Leaf Spots
Leaf spots on the magnolia tripetala are usually caused by a fungal issue. You will notice circular brown or black spots with yellow-ringed patches. The issue is spread by rain, dirty tools, people, animals, and insects, so it is hard to control but easy to manage. Remove infected leaves, water the soil, not the tree, rake fallen leaves from beneath the tree, and treat the tree with a general tree fungicide if infected.
Late Frosts
Unfortunately, late frost can cause flowers to drop prematurely. Worse yet, not much can be done to prevent this from occurring once a tree is planted. But suppose you live in an area where late frosts are known to occur and plan to plant a tree that is not particularly frost-hardy. In that case, you can plant it in a well-protected site that creates its microclimate, such as the corner between two walls or a depression protected by elevations on two or three sides.
III. Uses and Benefits
Magnolia tripetala contains a substance called ethyl acetate in its branches, and this substance displays nematicidal activity. This activity allows it to specifically resist Bursaphelenchus xylophilus, Panagrellus redivivus, and Caenorhabditis elegans.
Magnolia tripetala has been used as a parent with Magnolia obovata (Japanese cucumber tree), resulting in the hybrid Magnolia x pruhoniciana, an ornamental plant. The species is named for the park for which it was first discovered, Prühonice Park in the Czech Republic. The hybrid has resulted in multiple hybrid variants, including the named ‘Silk Road’ and ‘Silver Parasol’ cultivars. The variants are described to be deciduous, medium trees with elliptic to ovate leaves. The leaves are 20-45cm by 10-22cm and the flowers are white, 16-25cm across at the end of branches. The cultivars have fruits with features such as number of follicles or stamen scars that are intermediate between the parent species.
Umbrella magnolia leaves are eaten by a variety of animals. They often grow under the canopy of larger trees and support biodiversity in forested areas. These trees are notably used as specimen trees for their unique foliage. Magnolia tripetala is used ornamental in urban areas and used as fa ocal treesin garden settings.
