Star magnolia (Magnolia stellata): History, Cultivars, Growth Rate & Care

Magnolia stellata, the star magnolia, is a slow-growing deciduous shrub or small tree. It bears large, showy white or pink flowers in early spring, before its leaves open. This species is closely related to the Kobushi magnolia, and is treated by many botanists as a variety or even a cultivar of that. However, Magnolia stellata was accepted as a distinct species in the 1998 monograph by Hunt

The Star Magnolia was first introduced to the United States in 1862 by Dr. George Robert Hall (1820-1899), Magnolia stellata has been widely cultivated in much of North America, and has been recorded as an established escape in a few places. It is also a commonly grown ornamental in Europe, and was first introduced to the United Kingdom in 1877 or 1878, most likely by Charles Maries, while he was collecting for Veitch Nurseries.

In the wild, the Star Magnolia grows in moist, well-drained soils in woodlands and along streams. The tree is hardy in USDA zones 4 to 8, which means it can tolerate cold winter temperatures as low as -30°F. In its native Japan, the Star Magnolia is found in the highlands of Honshu, the largest of the Japanese islands. It grows by streamsides and in moist, boggy areas with such other woody plants. The tree’s attractive flowers and compact size make it well-suited for small gardens and urban landscapes.

The defining characteristic of the star magnolia is its flowers, which blossom to reveal bright white tepals in a star-shaped pattern. These flowers bloom in the beginning of spring and can last until the middle of summer if properly cared for. The star magnolia tree itself can grow up to 30 feet tall and presents foliage and flowers on several individual trunks that split off from the main trunk a few feet from the ground. The star magnolia is deciduous and loses its leaves in the winter after creating colorful fall foliage. The wood of the star magnolia tree is softer and weaker than other trees of its size and is susceptible to damage, even from wind.

Characteristics of Star Magnolia (Magnolia stellata)

  • The star magnolia is a shrub-like tree that produces fragrant blossoms that last throughout the spring and into the summer.
  • This shrub grows 1.5 to 2.5 metres (5 to 8 ft) in height, spreading to 4.6 m (15 ft) in width at maturity. 
  • The leaves open bronze-green, turning to deep green as they mature, and yellow before dropping in autumn. They are oblong and about 10 cm (4 in) long by about 4 cm (1.6 in) wide.
  • Generally have a rounded to spreading growth habit, with multiple stems branching from the base. They tend to have a dense and bushy appearance.
  • Young plants display upright oval growth, but the plants spread and mound with age.
  •  Have a moderate growth rate, typically growing around 6 to 12 inches per year under optimal conditions.
  • Produce showy, star-shaped flowers that bloom in early spring before the leaves emerge. The flowers can range in color from white to pale pink and have a delicate fragrance.
  • There is natural variation within the flower color, from white to rich pink; the pink also changes from year to year.
  • Produces a reddish-green, knobby aggregate fruit about 5 cm (2 in) long that matures in early autumn. 
  • This tree, best suited to U.S. Department of Agriculture plant hardiness zones 4 through 9.
  • Can live for several decades. They have a relatively long lifespan, often living 50 years or more.
  • Young twigs have smooth, shiny chestnut brown bark, while the main trunks have smooth, silvery gray bark. 
  • The root system of Star magnolias is typically shallow and spreading. They have fine feeder roots that extend outwards from the base of the plant to absorb nutrients and water from the soil.
  • Have a moderate growth rate, typically growing around 6 to 12 inches per year under optimal conditions.
  • Have slender, grayish-brown branches that are covered in smooth bark. The branches tend to be somewhat brittle and may require pruning to remove dead or damaged growth.

Cultivars of Star Magnolia (Magnolia stellata)

‘Centennial’One of the finest selections, this plant was released by Harvard’s Arnold Arboretum to commemorate the institution’s 100th anniversary in 1972. The many-petaled flowers are white with a hint of pink, while the upright, vigorous pyramidal plant reaches 25′ tall. It is considered one of the best cultivars and is very popular in the trade.
‘Jane Platt’A large shrub or small tree with a dense, compact habit. It features large, pure white flowers with up to 30 petals, and blooms later than most other star magnolias, making it less susceptible to frost damage.
‘Royal Star’A popular cultivar with large, pure white flowers and a compact, bushy habit. It blooms later than the species, reducing the risk of frost damage to the flowers.
‘Waterlily’A stunning cultivar with large, white flowers that resemble water lilies. It blooms later than the species, and has a slightly more upright habit.
‘Pink Star’A rare and unique cultivar with delicate, pale pink flowers. It is a small tree or large shrub with a spreading habit and blooms slightly later than the species.
‘Starbright’A small tree or large shrub with a dense, compact habit and large, pure white flowers. It blooms later than the species, making it less susceptible to frost damage.
‘Rosea’A small tree or large shrub with a spreading habit and large, pale pink flowers. It blooms slightly later than the species.
‘Star of Gold’A small tree or large shrub with a spreading habit and large, white flowers with a golden center. It blooms slightly later than the species.
‘Star of Persia’A small tree or large shrub with a spreading habit and large, white flowers with a purple tinge. It blooms slightly later than the species.
‘Star of Snow’A small tree or large shrub with a spreading habit and large, pure white flowers. It blooms slightly later than the species.

How to Grow a Star Magnolia From Cuttings

  • Combine equal measures perlite, sterile compost and medium-grit sand in a bucket. Stir the components until the sand and perlite are distributed evenly throughout the sterile compost. Add water and stir until the mixture feels moderately moist.
  • Pack the growing mixture into a 4-inch plastic pot. Press it gently to remove any air pockets. Poke a 2-inch-deep hole in the center of the mixture. Set the pot in a shaded location while gathering a star magnolia cutting.
  • Gather a 4-inch-long cutting from the tip of a healthy, vigorous star magnolia branch. Select one with a pliant stem, immature leaves at the tip and no buds or flowers. Sever the cutting 1/4 inch below a set of leaves using clean, sharp pruning shears.
  • Remove all the leaves from the lower half of the cutting. Cut the remaining leaves in half to decrease moisture loss. Use your pruning shears to cut the leaves or a pair of sharp scissors.
  • Scrape off a 1/4-inch-long and 1/8-inch-wide sliver of bark from the severed end of the cutting. Use a utility knife to scrape the cutting to produce a clean, shallow cut.
  • Press the severed end of the star magnolia cutting into 0.8-percent IBA rooting talc. Tap the stem gently to dislodge the excess powder.
  • Pot the star magnolia cutting in the prepared rooting pot. Insert the talc-coated end into the hole. Squeeze the growing mixture firmly against the stem to hold the cutting upright.
  • Place the potted star magnolia cutting where it receives bright, indirect sunlight, protection from strong winds and temperatures above 75 F. Warm the bottom of the pot with a heating coil if a suitably warm location is unavailable.
  • Maintain light moisture in the growing mixture while the cutting puts down roots. Mist the foliage twice daily with a water-filled spray bottle to keep it from dehydrating. Avoid saturating the growing mixture since the cutting might rot.
  • Check for roots in four to six weeks. Gently tug on the base of the stem and feel for resistance, which indicates that the cutting is anchored to the soil by roots. Remove the cutting from the heating coil after it has rooted.
  • Transfer the rooted cutting into a 6-inch plastic pot filled with potting soil four weeks after it has rooted. Grow it under light shade with morning and afternoon sun for its first summer. Move it to a sunny, sheltered spot during the autumn and winter.
  • Plant the star magnolia in a sunny or partially shaded bed the following spring when soil temperatures have warmed to 68 F. Choose a bed with moist, acidic soil and at least 10 feet of space between it and surrounding structures. Mulch heavily and keep the plant well watered during its first summer.

How to grow and care for Star Magnolia

  • Choose the right location: Star Magnolias prefer full sun to partial shade and well-drained, slightly acidic soil. Make sure the planting site has enough room for the tree to grow.
  • Planting: Plant your the Magnolia in the spring or fall. Dig a hole twice as wide and just as deep as the root ball. Place the tree in the hole, ensuring the top of the root ball is level with the ground. Fill the hole with soil and water thoroughly.
  • Watering: These Magnolias require regular watering, especially during the first few years after planting. Water deeply once or twice a week, depending on the weather conditions. Avoid overwatering, as this can lead to root rot.
  • Mulching: Apply a 2-3 inch layer of organic mulch around the base of the tree, making sure to keep it a few inches away from the trunk. This will help retain moisture, regulate soil temperature, and prevent weed growth.
  • Fertilizing: Apply a slow-release, balanced fertilizer in the spring, following the manufacturer’s instructions. Avoid over-fertilizing, as this can lead to excessive leaf growth and reduced flowering.
  • Pruning: Prune your Magnolia in late winter or early spring, before new growth appears. Remove any dead, diseased, or crossing branches, and shape the tree as desired. Avoid heavy pruning, as this can reduce flowering.
  • Pest and disease control: These Magnolias are relatively pest and disease-resistant, but they can be susceptible to magnolia scale and fungal diseases like leaf spot and powdery mildew. Monitor your tree for signs of these issues and treat them promptly with appropriate control measures.
  • Winter protection: In colder regions, protect your Magnolia from frost damage by wrapping the trunk with burlap or tree wrap and insulating the root zone with a thick layer of mulch.