In short
- The smallest of the commonly grown magnolias - usually 2-3 m tall, older specimens up to about 4 m, and at least as wide as it is tall.
- Blooms in March and April, before the leaves emerge, earlier than the saucer magnolia.
- The flower has 12-18 narrow, strap-shaped tepals; double-flowered cultivars have more than 30.
- Early flowering means a risk of frost damage - plant it in a sheltered spot and avoid east-facing exposures.
- It has shallow, fleshy roots: do not dig the soil beneath the shrub, mulch it, and never let it dry out.
Botanical data
- Family
- Magnoliaceae (Magnoliaceae)
- Height
- 2–4 m
- Width
- 2.5–4 m
- Habit
- Spreading
- Growth rate
- Slow
- Position
- Full sun, Partial shade
- Soil
- Humus-rich, Loamy, Sandy
- pH reaction
- pH 5.5–7
- Moisture
- Moderate, Moist
- Bloom
- March–April
- Hardiness
- USDA 4a–8b
- Propagation
- From cuttings, By layering, From seed
Characteristics
A deciduous shrub with a dense, broadly rounded crown - upright when young and increasingly spreading with age. It grows with many stems from ground level, which keeps its shrubby rather than tree-like habit; older specimens trained on a single trunk take on the form of a small tree. It grows slowly - reaching its final size takes 10-20 years, which makes it an exceptionally predictable plant for small plantings. Young twigs have smooth, glossy, chestnut-brown bark, older trunks a silvery grey. The flower buds are set in the summer of the previous year and overwinter on leafless shoots as densely hairy, silvery "catkins" that are decorative in their own right. The flowers open in March and April, before the leaves, are 5-10 cm across and consist of 12-18 narrow, strap-shaped tepals - and more than thirty in double-flowered cultivars. They are white, in many cultivars flushed with pink, especially in bud and just after opening, and gently fragrant. The leaves appear only after flowering: narrowly obovate, 5-13 cm long, with a brownish tint in spring, dark green in summer and turning yellow in autumn. The fruit is a cone-shaped, follicular fruit cluster about 5 cm long, splitting in autumn to reveal orange seeds; on garden shrubs it sets irregularly. The root system is shallow and fleshy - sensitive both to mechanical damage and to drying out of the topsoil.
Popular cultivars
- ‘Royal Star’
- The cultivar most commonly found in the trade, a seedling of 'Waterlily'. Pale pink and silvery buds open into pure white flowers with about 25 tepals. It blooms a little later than the type, which reduces the risk of the flowers freezing, and is exceptionally hardy. Awarded the RHS Award of Garden Merit.
- ‘Waterlily’
- Pink buds, white flowers with a pink flush, with more than 30 tepals, distinctly fragrant. It blooms 1-2 weeks later than the typical star magnolia, so it more often escapes spring frosts.
- ‘Rosea’
- An old cultivar with silvery pink buds that open into pale pink flowers fading almost to white. The tepals are few - up to about thirteen, that is distinctly fewer than in double-flowered cultivars, which lets the flower keep a clear, starry outline.
- ‘Jane Platt’
- A cultivar with a distinctly more intense pink than most star magnolias, with the number of tepals reaching thirty, that is roughly twice as many as in 'Rosea', from which it derives. Found in the garden of Jane Platt in Portland, Oregon, and for a time distributed erroneously as 'Rosea'. Very free-flowering, awarded the RHS Award of Garden Merit.
- ‘Centennial’
- Introduced in 1972 by the Arnold Arboretum of Harvard University to mark the centenary of that institution. The flowers are exceptionally large, up to about 14 cm across, with 28-33 tepals, usually pure white. The shrub is more vigorous and faster-growing than the type.
Growing and care
Watering
Shallow, fleshy roots tolerate drying out poorly - in dry years water generously, especially in the first seasons after planting. In the wild the species grows in boggy places, so it copes with periodic strong wetting better than many other magnolias, but it does not tolerate permanently waterlogged ground. In winter a shrub planted in the ground needs no watering; the exception is snowless, dry and frosty winters, when young specimens are worth watering once every few weeks, on a day with above-freezing temperatures.
Fertilizing
Moderate. Mulching with pine bark protects the shallow roots, keeps the soil moist and slightly acidifies it. On strongly calcareous and drying-out soil chlorosis may appear - iron chelate and regular mulching then help. Star magnolia is, however, one of the magnolias that best tolerate an alkaline reaction, as long as the soil stays moist and humus-rich.
Planting
Fertile, humus-rich, well-drained but consistently slightly moist soil with an acid to neutral reaction. On sandy soil it is essential to enrich it abundantly with humus and to mulch it constantly - otherwise the shallow roots quickly dry out. A sunny position or one in light partial shade, sheltered from cold winds; avoid east-facing exposures, where rapid thawing after a night frost destroys the flowers.
Pruning
Limit yourself to removing dead, damaged and crossing shoots and to cutting out individual shoots crowding the interior of the shrub.
Companion plants
Good companions
Obie rośliny wymagają próchnicznej, kwaśnej i stale lekko wilgotnej gleby oraz stanowiska osłoniętego od wiatru — to klasyczne zestawienie rabaty kwasolubnej.
Kwitnie w tym samym momencie co magnolia, u jej stóp, gdy krzew jest jeszcze bezlistny; płytkie cebule nie kolidują z korzeniami magnolii.
Znosi cień rzucany przez rozłożysty krzew, lubi tę samą wilgotną, próchniczną glebę i osłania powierzchnię gruntu, ograniczając przesychanie płytkich korzeni magnolii.
Bad companions
Lawenda wymaga gleby suchej, ubogiej i szybko przesychającej, a magnolia gwiaździsta — stale lekko wilgotnej i próchnicznej; jej płytkie, mięsiste korzenie źle znoszą przesuszenie. Ściółkowanie i podlewanie potrzebne magnolii sprzyja u lawendy zgniliźnie podstawy krzewu.
Płytkie, mięsiste korzenie magnolii sięgają tuż pod powierzchnię i łatwo je uszkodzić szpadlem, co osłabia krzew i pogarsza kwitnienie.
The evidence level indicates whether the relationship is backed by research, observation, or gardening tradition.
Diseases and pests
The symptom affects acid-loving plants — hydrangea, rose, rhododendron, blueberry and others — grown on alkaline or calcareous soils. The leaf blade turns yellow while the veins remain distinctly green, producing the characteristic interveinal chlorosis. The symptoms appear first on the youngest leaves at the shoot tips, because iron is not very mobile within the plant and is not translocated into new growth. In extreme cases the leaves are almost white and their margins dry out. Crucially, the cause is usually not a lack of iron in the soil but too high a pH, which blocks its uptake by the roots. It is worth noting that not all susceptible plants are equally acid-loving — the rose prefers a slightly acidic to neutral reaction (about pH 6–7) and also develops iron chlorosis on strongly alkaline, calcareous soils, although it is not acid-loving in the way rhododendron or blueberry is. The pattern of yellowing is very regular: not only the main vein stays green but the whole fine network of veins, so that the leaf looks like green lace on a yellow-green background — this is the most reliable diagnostic feature, distinguishing interveinal chlorosis from the uniform, whole-surface yellowing typical of nitrogen deficiency. The symptoms intensify with each successive flush: older leaves at the base of the shoot may still be green or only slightly paled, and the younger the leaf, the paler it is, up to almost white, lemon-yellow tips. Under a long-lasting deficiency the margins and tips of the youngest leaves turn brown and necrotic, shoots grow more weakly and become smaller, and in blueberry the yield and fruit quality decline. Iron chlorosis is not contagious — it does not spread from plant to plant but appears simultaneously in all specimens growing on the same, overly alkaline site, which also helps to distinguish it from infectious diseases. Its severity can vary through the season: cold, wet and compacted soil, poor root aeration, excess calcium, a high bicarbonate content in the watering water, and over-fertilization with phosphorus additionally hinder iron uptake and aggravate the symptoms even when the element is not lacking in the soil.
Armoured and soft scale insectsImmobile, brown or yellowish shields (1-4 mm) attached to stems and the underside of leaves, especially along the veins. Easily mistaken for growths on the plant. They suck sap, causing yellowing and weakening, and excrete sticky honeydew. Common on figs, orchids and plants with tough leaves. The collective name covers two groups with different biology. Armoured scales (Diaspididae) have a hard waxy shield separate from the body, which can be prised off - beneath it emerges a tiny, legless and wingless female; they do not excrete honeydew. Soft scales (Coccidae) have a convex, cup-shaped cover fused with the body, and it is they that excrete it abundantly. Sticky honeydew - the domain of soft scales and other honeydew-producing scale insects, not of armoured scales - settles on the leaves and attracts sooty mould fungi (sooty mould, sooty blotch) as well as ants, which defend the colony against predators. The only mobile feeding stage is the crawler - a flat, tiny larva which, after hatching from beneath the mother's shield, disperses over the plant, then settles, inserts its stylet into the conducting tissues and loses the ability to move; adult females remain immobile for the rest of their lives. Males pupate and, as tiny, winged, short-lived insects, do not feed. In heated interiors the pest breeds all year round, producing several overlapping generations; outdoors usually 1-3 generations, and fertilised females or eggs hidden beneath the shield overwinter. Feeding symptoms are yellowing and premature leaf drop, dieback of shoots, stunting and weakening of the plant, and secondarily a black coating of sooty mould on leaves covered with honeydew. On fruit trees infested by San Jose scale (Comstockaspis perniciosa), reddish discolouration appears around the feeding sites, and heavily colonised branches die back. Because the shields are immobile and their colour blends into the bark and veins, an infestation is easily overlooked until honeydew appears or the plant is noticeably weakened - which is why regular inspection of the leaf undersides and shoot axils is key.
Toxicity
| For whom | Level | Notes |
|---|---|---|
| Humans | None | — |
| Dogs | None | — |
| Cats | None | — |
History and origin
The species is endemic to central Japan: it grows only in the Tokai region, on the border of the Gifu, Aichi and Mie prefectures, at elevations from a few dozen up to about 550 m above sea level, in boggy thickets, along streams and on the edges of wetlands. In the wild it is a threatened species - the remaining sites are fragmented, and most local populations number fewer than a hundred individuals. This gives rise to a paradox: a plant common in gardens around the world is at the same time a rarity in its own homeland. In Japan it has been grown for centuries as a flowering pot plant under the name shidekobushi. It reached Western gardens in 1861-1862 thanks to George Rogers Hall, who sent it to Rhode Island, from where it spread through American nurseries; it was introduced to Britain in the 1870s, among others by Charles Maries for the Veitch nursery. For much of the 20th century it was treated as a botanical variety, Magnolia kobus var. stellata, and only later taxonomic treatments established its rank as a separate species. Crossing it with Magnolia kobus produced the hybrid Magnolia x loebneri, to which the cultivars 'Leonard Messel' and 'Merrill', very popular in the trade, belong - they are sometimes mistakenly described as star magnolia.
Uses
Star magnolia is the go-to choice wherever there is no longer room for a saucer magnolia: in small gardens, front gardens, by a terrace and beside a house entrance, where the early flowering can be admired at close range. It is planted singly as a specimen against a lawn or a dark wall of greenery that sets off the white of the flowers, and also in groups along the edges of beds with acid-loving shrubs - rhododendrons, azaleas or lingonberry. It looks good underplanted with early geophytes: crocuses, squills and snowdrops flower at the same moment, and their shallow bulbs do not interfere with the shrub's root system. Its compact habit and slow growth allow it to be grown in large containers on a terrace, provided it is watered regularly and the root ball is protected over winter. It is not, however, suitable for clipped hedges or for places where it would have to be regularly cut back - magnolias tolerate pruning poorly and heal their wounds slowly. Nor is it a plant for cut-flower arrangements: the flowers are very delicate and drop quickly.
Trivia
- In Japan, star magnolia has been grown for hundreds of years as a flowering pot plant, known under the name shidekobushi.
- A species common in gardens is threatened in the wild: it grows wild only in one region of central Japan, and about three quarters of the local populations there number fewer than a hundred individuals.
- The cultivars 'Leonard Messel' and 'Merrill', sold as "star magnolias", actually belong to the hybrid Magnolia x loebneri, that is a cross of Magnolia stellata with Magnolia kobus.
- In magnolias, petals and sepals are not distinguished - all the perianth segments look alike and are called tepals; this is a trait of evolutionarily very ancient flowering plants.
Frequently asked questions
How does star magnolia differ from the saucer magnolia?
Star magnolia is distinctly smaller (usually 2-3 m, up to about 4 m) and grows as a multi-stemmed shrub, whereas the saucer magnolia forms a tree or a large shrub several metres tall. They also differ in their flowers: the star magnolia has 12-18 narrow, strap-shaped tepals spreading out flat into a star, while the saucer magnolia has broad tepals forming a goblet or tulip. The star magnolia blooms earlier, usually in March and April.
Is star magnolia suitable for a small garden?
Yes, it is the most frequently recommended magnolia for small plots. It grows slowly and after 10-20 years usually reaches 2-3 m, then grows on very slowly; the oldest specimens reach about 4 m. Bear in mind, though, that it can be at least as wide as it is tall - when planning its position, it is worth reserving 2.5-4 m of space sideways, not only vertically.
Why do star magnolia flowers turn brown?
Most often this is the effect of spring frosts - the species flowers very early, so the buds and open flowers are exposed to frost. It is worth planting the shrub in a spot sheltered from wind and avoiding east-facing exposures, where rapid thawing in the morning sun after a night frost harms the petals most. The risk is also reduced by cultivars that flower a little later, for example 'Royal Star' or 'Waterlily'.
When and how should star magnolia be pruned?
As rarely as possible and preferably in high summer - roughly from July to early autumn, when the shrub is in full leaf and the wounds heal best. At that time you remove dead, damaged and crossing shoots. Pruning in winter and early spring removes the flower buds set the previous summer and causes heavy bleeding of sap, and magnolias heal their wounds slowly - which is why hard cutting back of the shrub is a mistake.
Why do star magnolia leaves turn yellow between the veins?
This is usually a symptom of iron chlorosis, which appears on strongly calcareous and drying-out soils - the plant cannot take up enough iron from them. As a short-term remedy iron chelate helps, and as a lasting one, mulching with pine bark and keeping the soil consistently moist. The optimal reaction is acid to neutral (pH about 5.5-7.0), but star magnolia tolerates alkaline soil better than most magnolias, as long as it does not dry out.
Sources
- Plants of the World Online (POWO) — Magnolia stellataDatabase (GBIF, POWO…)
- RHS — Magnolia stellata (star magnolia)Institution / botanical garden
- Trees and Shrubs Online (International Dendrology Society) — Magnolia stellataWebsite
- NC State Extension Gardener Plant Toolbox — Magnolia stellataInstitution / botanical garden
My note
A private note for this plant — saved in your browser.
