If you’re looking for a magnolia tree that can handle the cold, this Japanese native is the perfect pick. It is low-maintenance, widely adaptable, and hardy down to a whopping -30°F (-34°C)! Unlike its southern magnolia relatives, star magnolia trees are hardy to zone 4 and come from mountainous regions.

Growing up in tropical zone 11, I had no idea how beautiful any of the magnolia trees were. Certainly, I had seen photos of their large, creamy white blooms, but without seeing one in person, it’s hard to grasp the true beauty of a plant. When in college in North Florida, I first encountered the Japanese magnolia. I was smitten from the first look.

One smaller subset species worth adding to the garden is the star magnolia tree or Magnolia stellata. Here’s how to grow this showstopper!

What is a Star Magnolia Tree?

Japanese magnolia species tolerate cold better than evergreen types and thrive in more climate zones.

Japanese magnolias are wonderful blooming trees that prefer mild climates. They are more cold-tolerant than the evergreen types, so you can grow them in a wider range of climate zones.

These deciduous trees produce incredibly beautiful flowers in spring, soft, attractive foliage in summer, and they even offer a bit of fall color. They are relatively easy to care for and require only a modicum of maintenance once established. 

Characteristics

Flowers measure one to four inches, usually white, occasionally yellow or pink, with elongated straplike petals.

This star of the garden is a flowering deciduous small tree or large shrub. Compact varieties of star magnolia trees may only reach 10 feet tall, while standard types may grow up to 25 feet at maturity. They are moderate growers, putting on between one and two feet per year, depending on their environment. 

In general, Japanese magnolia species are spring bloomers, though they vary by species. Star is an early bloomer, beginning in February, depending on the climate. The colder the climate, the later they bloom, up until about April. The flowers open from soft, fuzzy buds and look like large, white stars, which is where this species gets its name. 

The flowers are between one and four inches across and are usually pure white. A couple of cultivars have yellow undertones, and some have a touch of pink. Depending on the variety, they have between 7 and 30 petals and a light, pleasant fragrance. 

Rather than the rounded, tulip shape of other plants in the genus, these have elongated, straplike petals. Orange fruit cones develop over the summer and provide food for birds in the fall. 

They can have one or multiple trunks, depending on how you prune them while young. In general, they have more branching than other Japanese cultivars. The bark is attractive, lightly textured, and silvery gray. The foliage is soft and oblong. It changes to bronze in the fall, but it’s not particularly noteworthy in contrast to the spring blooming habit. 

Water the tree well before planting to hydrate it, which reduces shock. It’s a great idea to amend your soil with compost to give it an extra boost from the beginning. Position your root ball in the hole and backfill, then water it thoroughly. 

For the first three to six months, water it two to three times per week. Once established, continue to water weekly in the absence of rain for the next two years. Applying a layer of mulch around the base will help hold in moisture, which magnolias appreciate. Leave some space around the trunk to avoid fungus and pest infestation. 

How to Grow

A newly planted magnolia needs attention for root establishment; afterward, they’re low-maintenance and provide long-lasting beauty.

Initially, your star magnolia will need some attention to establish those roots. Once that happens, this low-maintenance plant will bring years of enjoyment with very little effort. 

Light

They need full sun, except in hot climates where afternoon shade prevents foliage burn.

Full sun is the general exposure requirement for this species and other Japanese magnolias. They grow and flower best with six to eight hours of sun daily.

The exception to this is in the southern reaches of their range, where summers can be intensely hot. In these areas, a bit of shade in the afternoon will save it from foliage burn. 

Water

Water every two to three days initially, then weekly for two years; deep watering encourages root growth.

As I mentioned above, your newly planted tree will need regular watering. Water every other to every third day for the first three to six months. Consider rainfall, as you don’t want to end up with swampy soil, which can lead to root rot. 

For the first two years after that, make sure it gets water once weekly. If that comes in the form of rain, you don’t have to give additional water. When you water, water deeply, allowing it to soak the ground and help the roots move deeper. 

Once established, these are quite drought-tolerant. I have an eight-year-old tree that requires little to no attention for 11 months out of the year. 

Soil

The ideal soil includes nutrient-rich, slightly acidic loam with sand and clay.

They are flexible in terms of soil composition. Heavy clay soil may present a problem, but it’s nothing that amending with some compost and sand can’t remedy. Test your soil’s pH before planting, as alkaline soil won’t support this tree well. 

The ideal soil for your star magnolia tree is nutrient-rich, slightly acidic, and a mix of sand, clay, and loam. Loosen compacted soil to help with root development. They are not salt-tolerant, so they don’t grow as well in coastal areas, sadly. 

Temperature and Humidity

It tolerates extreme temperatures from -30°F to 95°F but needs extra water during heat waves.

Star magnolia trees are tolerant of a wide range of climates and temperatures. They are cold-hardy down to -30°F (-34°C) and also easily handle temperatures up to 95°F (35°C). I have seen issues with leaves drying and falling when we experience an extended heat wave, but they usually rebound as the weather returns to normal. Giving some extra water during these times will help. 

They tolerate humidity well, although they don’t need an exceptional amount. They are happiest in a range of 30-50% humidity. If you’re growing this indoors as a houseplant, a bit more humidity is ideal, somewhere in the range of 40-60%.

Fertilizing

Fertilize only if the soil lacks nutrients; compost and mulch improve soil texture and maintain slight acidity.

Fertilizing is not imperative as long as the soil is acidic and rich in organic matter. Top dressing with compost and mulch in the fall will help keep the soil loose, rich, and slightly acidic. If the soil is too alkaline, you’ll need to fertilize more often. 

If the soil is in an ideal state, you can fertilize once in the winter before the plant flowers. Use either a balanced formula of 10-10-10 or one for blooming trees with higher levels of phosphorus and potassium. 

Maintenance

Once established, Japanese magnolia species need minimal watering, fertilizing, and pruning. Their self-cleaning blooms require no deadheading.

These are low-maintenance trees once established. They are self-cleaning, so they don’t require deadheading. They also require little additional water and fertilizer after the first two years. Japanese magnolias don’t require yearly pruning, and in fact, you should avoid pruning if possible. 

These trees grow in a naturally balanced and attractive shape. Too much pruning will disrupt this shape and can lead to water spouts and other oddly shaped and placed branches. 

While young, you can prune off the lower branches if you want more of a tree shape. For a shrubbier plant, don’t worry about pruning unless you see dead or diseased branches and foliage. If you need to remove crossing branches or water spouts, do so right after it finishes blooming. 

Propagation

Propagate in the spring by stem cuttings or layering; cuttings flower earlier than seeds.

Star magnolias are most commonly propagated in the spring, with stem cuttings. When you grow them from seeds, the germination rate is unpredictable, and you’re unlikely to see flowers for quite some years. Those propagated from cuttings can flower in as few as two years. You can also propagate by layering, which achieves a similar timeline to propagation from cuttings.

Popular Varieties

‘Centennial’

This cultivar produces five-inch white blooms with pink stripes and up to 33 slender petals.

‘Centennial’ is a mid-sized star magnolia with a wonderful blooming habit. The flowers are bountiful and large for the species, at just over five inches across. They’re packed with petals, up to 33 per bloom, which are white with a pink stripe beneath that creates a pink tint in the center. 

The flowers open to reveal a small cluster of cream-colored stamens. They are moderately fragrant. This cultivar has won the Award of Garden Merit from the Royal Horticultural Society and the Gold Medal from the Pennsylvania Horticultural Society. 

‘Gold Star’

It has four-inch yellow-leaning blooms with 12 petals and earned the Award of Garden Merit.

‘Gold Star’ is one of the cultivars with flowers that lean more in the yellow direction. It’s a medium to large variety with medium-sized (4-inch) flowers with about 12 petals and a green and yellow center. It’s also an Award of Garden Merit winner.  

‘Jane Platt’

This variety has showy pale pink flowers with darker stripes, growing in striking terminal clusters.

‘Jane Platt’ is one of the most eye-catching varieties, as it has incredibly flamboyant flowers. The blooms are medium-sized but grow in terminal clusters for extra effect. The petals are pale pink with a darker pink stripe underneath, and there are tons of them! It’s no wonder this is another winner of the RHS Award of Garden Merit.

Common Problems

These hardy trees resist pests and diseases best when monitored regularly to catch early problems.

These are not high-maintenance trees, but several pests and a few diseases can affect them. The best way to prevent extensive damage is to keep an eye on them and notice issues as early as possible. 

Pests

Magnolia scale insects attach to twigs, suck sap, and promote black sooty mold formation.

The most important pest to look out for is magnolia scale. They are the largest-scale insects, and this is their preferred food. The young will love about under leaves, while the adults are stationary and usually found on twigs where they attach and suck sap. They can cause black sooty mold, which grows in their sticky excrement and interferes with photosynthesis. 

Aphids, spider mites, and beetles can all crop up on this tree, but they are less common. Neem oil is a good way to get rid of these. Scales tend to be difficult as they latch on pretty tightly, so horticultural and neem oils help to break down their outer shell. Wait until there are no flowers to treat, as these treatments can harm pollinators.

Diseases

Common fungal diseases include leaf spot, verticillium wilt, canker, blight, honey fungus, and root rot; avoid overwatering.

Fungal diseases are the most common issue in this category. Leaf spot, verticillium wilt, canker, blight, honey fungus, and root rot are all possible foes. Most of these are the product of improper and overwatering. Water at the ground level to keep moisture from sitting on the leaves. Don’t let the soil become waterlogged, as this can cause root rot. 

Frequently Asked Questions