Lespedeza thunbergii, Thunberg's lespedeza or bush clover, is a sub-shrub or shrubby perennial in the legume family (Fabaceae) that is among the best of all garden plants for late summer and autumn interest. Native to Japan and China, it dies back completely to the ground each winter and then regrows from the crown in late spring with remarkable vigour, sending up long wand-like stems that arch over like a fountain as they lengthen through July and August. By September the plant has reached one and a half to two metres, and it is then that it comes into its own: the arching stems carry cascading sprays of small, purple-pink pea flowers in tremendous profusion, exactly when almost everything else of similar stature has finished flowering. In October it is still flowering freely. The effect is spectacular and, in a season when late colour is so valuable, essentially unrivalled among hardy shrubs of this scale.
The cultivar 'Gibraltar' is the most widely grown form, vigorous and free-flowering with deep rose-purple flowers carried on strongly arching stems. 'White Fountain' has white flowers and a slightly more compact, elegantly arching habit that suits smaller gardens or positions where the full exuberance of 'Gibraltar' would be too much. The closely related Lespedeza bicolor flowers earlier, in July and August, and has a more upright, shrubby habit, making it a useful companion to extend the lespedeza season backward into late summer. Both species are fully hardy in most UK gardens, tolerant of chalk and thin dry soils, and attractive to bumblebees and other pollinators at a time of year when nectar sources are genuinely scarce.
The trifoliate leaves, composed of three small oval leaflets, are the plant's working parts through the long growing season from May to October, and when they curl it is worth identifying the cause promptly to protect the plant's energy heading into its main flowering period. Here is what to look for.
Drought stress
Drought stress is the most common reason lespedeza leaves curl, and it is particularly important to understand in the context of this plant because lespedeza is often praised as drought-tolerant, which it is, but not unconditionally and not during its first two seasons in the ground. When water is in short supply, the trifoliate leaflets curl inward along their length, folding upward around the midrib to reduce the transpiring surface exposed to sun and wind. Affected leaves may also take on a slightly dull, grey-green tone as the plant reduces water movement through the leaf tissue. In severe drought the longest stems, which carry the most leaf area and lose the most water, wilt noticeably in the afternoon heat even when the morning appeared normal.
The reason newly planted lespedeza is disproportionately vulnerable to drought is straightforward: the root system of a plant in its first or second year has not yet spread and deepened into the surrounding soil, and the plant is therefore dependent on moisture within a relatively small volume of soil that can be exhausted quickly in dry weather. An established lespedeza of four or five years, with a wide-spreading root network drawing moisture from a large volume of soil, can typically manage a prolonged UK summer drought without supplementary watering. A plant in its second season may look much the same above ground but has nothing like the same below-ground resilience.
The scale of the above-ground growth that lespedeza produces from the base each season compounds the problem. By late July the plant is carrying an enormous area of leaf on stems that may be one and a half to two metres long, all of it transpiring water on a warm day. This leaf area can cause even a moderately established plant to wilt surprisingly quickly in very dry, hot weather, not because the plant is fundamentally drought-intolerant but because the ratio of leaf area to root mass is simply very high during the peak of the growing season.
Water lespedeza in prolonged dry spells through its first two years, giving the root zone a thorough soaking rather than frequent light sprinklings, which encourage the roots to stay near the surface rather than going deeper. A mulch of bark chips or garden compost applied over the root zone in spring, kept clear of the crown itself, conserves moisture significantly through the summer and is worth doing every year on any lespedeza for the first several seasons. Established plants on most UK soils manage without watering, but even mature specimens on very free-draining soil over chalk or gravel may show some leaf curl in an exceptional drought and will benefit from one or two deep waterings through the driest period to maintain the vigour they need to flower well in September.
Aphids and other sap-sucking insects
Aphids colonise the soft new growth of lespedeza in early summer, typically from May onwards as the long new stems are extending rapidly. Generalist aphid species as well as legume-specialist species such as the pea aphid (Acyrthosiphon pisum) are attracted to the abundant, soft, fast-growing shoot tips that lespedeza produces during its period of most active extension growth. The aphids cluster on the undersides of the youngest leaves and on the growing tips of the stems, feeding by piercing the plant tissue and extracting sap. The characteristic sign is downward curling of the youngest leaves, often accompanied by puckering and a slight distortion of the growing tip, and sticky honeydew deposits on the leaf surfaces below the feeding sites. On a heavily infested shoot the growing tip may appear congested and distorted, with the youngest leaves tightly curled and the aphid colony visible on inspection.
On an established lespedeza producing vigorous growth, aphid colonies in early summer are usually a minor nuisance rather than a significant problem, and natural predators typically bring the population under control before it causes lasting damage. Parasitic wasps, hoverfly larvae, ladybirds, and lacewings all feed on aphid colonies, and the natural control tends to catch up with the pest population by midsummer. On younger plants, where the total amount of new growth is less abundant and a significant colony on the shoot tips represents a larger proportion of the plant's productive leaf area, intervention may be warranted if the infestation is heavy.
Treat with a strong jet of water directed at infested shoot tips, which physically dislodges large numbers of aphids without harming natural predators. Insecticidal soap or a dilute washing-up liquid solution applied to the shoot tips and affected leaf undersides kills aphids on contact and degrades quickly, leaving no persistent residue. Avoid broad-spectrum insecticides, which eliminate the predatory insects that provide the most reliable long-term control and disrupt the natural balance through the rest of the season. Other sap-sucking insects, including capsid bugs, may occasionally damage lespedeza shoot tips, producing ragged holes and distorted growth as well as leaf curl, but these are uncommon and rarely require treatment on established plants.
Other causes of curling leaves
Slug damage to the emerging shoots in spring is worth watching for because lespedeza is particularly vulnerable at a specific and predictable moment: the point in late spring when the new growth emerges from soil level and the first few centimetres of soft shoot are exposed above ground before the stems have begun to toughen. The emerging shoots of lespedeza are fleshy and palatable, and slugs feeding on them at this stage can remove or badly damage the growing tips before the plant has a chance to establish the season's growth. Affected shoots emerge stunted or distorted, and the first leaves may show irregular holes or ragged edges alongside curling from the direct feeding damage. A ring of horticultural grit or copper tape around the emerging shoots provides effective protection during this vulnerable period. Once the stems have extended beyond the first few centimetres and the foliage is no longer emerging at slug level, the risk diminishes rapidly.
Powdery mildew can affect lespedeza in warm, dry conditions in late summer, producing a white powdery coating on the leaf surfaces and causing marginal curl on affected leaves. As a member of the Fabaceae, lespedeza is susceptible to the powdery mildew fungi that specialise in leguminous plants. The disease develops most readily on plants under drought stress in positions with limited air circulation, and it typically appears in August or September, just as the plant is entering its main flowering period. On a vigorously growing lespedeza in a good open position, late-season powdery mildew is primarily cosmetic and does not significantly affect flowering or the plant's capacity to grow well in the following year. Improving airflow around the stems and avoiding drought stress through the summer are the most effective preventive measures.
In severe winters or in exposed positions, the crown of lespedeza can be killed by prolonged hard frost. This is distinct from the normal winter die-back of the stems, which happens every year and is entirely natural. If the crown is killed, no new growth emerges in spring and the plant does not regrow. This outcome is uncommon in most UK gardens, where lespedeza is fully hardy, but it is a risk in the coldest and most exposed positions in northern England and Scotland, or in a site with no shelter from wind chill. A thick mulch of bark chips or composted bark applied over the crown in late autumn provides meaningful protection in borderline positions.
Prevention and long-term care
Cut the dead stems to ground level each spring, either in late winter or when the first signs of new growth appear at the base. Removing the old stems promptly allows the new growth to emerge unobstructed and reduces the risk of the old woody material harbouring pests or disease. If you leave the dead stems standing through winter for structural interest, which is perfectly reasonable given that the arching forms are attractive even when bare, cut them back to ground level in late February or March before the new growth begins to emerge.
Apply a mulch of bark chips or garden compost over the root zone each spring, keeping it clear of the crown itself to avoid encouraging rot at the base of the emerging shoots. The mulch conserves moisture through the summer, moderates soil temperature, and suppresses competing weeds around the base of the plant. This is the single most useful thing you can do to support lespedeza through a dry summer.
Protect the emerging shoots from slugs in the critical first few weeks of spring growth by placing a ring of horticultural grit or copper tape around the base of the crown as the first growth appears. Once the stems are a few centimetres tall and actively extending, slug risk diminishes substantially.
Water in prolonged dry spells, particularly in the first two years after planting, and maintain watering through dry periods from midsummer onwards to support the plant through the period of most active growth and into its September and October flowering season. A lespedeza that runs short of water in August may produce fewer flowers in September than one that has been well supported through the dry months preceding flowering.
In late autumn, once the stems have died back, apply a fresh mulch over the crown, particularly on a newly planted specimen or in an exposed position. This is straightforward insurance against hard frosts and is worth doing consistently for the first few years until the plant is fully established and the crown is well-developed.
Frequently asked questions
Why are my lespedeza leaves curling?
Drought stress is the most common cause of lespedeza leaves curling, particularly in the plant's first two years before the root system is fully established. The trifoliate leaflets curl inward along their length as the plant reduces its transpiring surface in dry conditions. Aphids on the soft new growth in early summer cause downward curling and distortion of the youngest leaves. Powdery mildew in late summer can produce marginal leaf curl alongside a white powdery coating. Slug damage to the emerging shoots in spring and frost damage to the roots in severe winters are less common causes.
Why does my lespedeza die back to the ground every winter?
This is completely normal behaviour for Lespedeza thunbergii and related species, and it is not a sign that the plant has died or been damaged. Lespedeza is a sub-shrub or shrubby perennial, meaning the long arching stems die back to the ground each winter and regrow from the crown and root system each spring. In UK conditions, even a fully established plant loses its stems completely in winter. New growth emerges from the base in late spring and grows vigorously through summer, reaching up to two metres and producing the long fountain-like arching stems that carry the flowers in September and October. Cutting the dead stems to ground level in late winter or early spring tidies the plant and does not affect flowering, which is produced on the current season's growth.
When does Lespedeza thunbergii flower?
Lespedeza thunbergii flowers in September and October, making it one of the last shrubs to bloom in the UK garden year and exceptionally valuable for late-season interest when most other flowering shrubs have already finished. The long arching stems, which can reach one and a half to two metres in a single season, carry cascading sprays of small purple-pink pea flowers that are produced in tremendous abundance. The cultivar 'Gibraltar' is particularly vigorous and free-flowering, with deep rose-purple flowers. 'White Fountain' has white flowers and a more compact, gracefully arching habit. The related Lespedeza bicolor flowers earlier, in July and August, and the two species together extend the lespedeza season across much of late summer and autumn.
How do I protect lespedeza from frost in winter?
The stems of Lespedeza thunbergii die back naturally each winter, so there is nothing to protect above ground. The part that needs protection is the crown, the woody base at soil level from which new growth emerges in spring. In most UK gardens, an established lespedeza crown is fully hardy and needs no protection at all. In exposed positions, in the colder parts of northern England or Scotland, or in a particularly severe winter, a thick mulch of bark chips or composted bark applied over the crown in late autumn provides meaningful insulation against hard frosts. A new plant in its first winter is more vulnerable than an established one because the root system has not yet spread and deepened, and mulching in the first autumn is always worthwhile as a precaution.
Is lespedeza good for wildlife?
Yes, and particularly valuable for pollinators in autumn. Lespedeza thunbergii flowers in September and October, a period when nectar and pollen sources are scarce in most gardens, and the abundant small pea flowers attract bumblebees, honeybees, and various solitary bee species at a time when they are still foraging to build winter reserves. As a member of the Fabaceae, lespedeza also fixes atmospheric nitrogen through root nodules, which benefits the soil. The cascading stems and dense flower sprays provide cover for insects through late autumn. In combination with other late-season plants such as salvias, sedums, and asters, lespedeza makes a significant contribution to sustaining pollinator populations through the autumn period.