Plant problems

Why Are My Pomegranate Leaves Curling?

Q: Why are my pomegranate leaves turning yellow?

Pomegranate leaves yellowing in the UK most commonly indicates natural leaf drop (pomegranate is deciduous and sheds all its leaves in autumn), iron or nitrogen deficiency, overwatering, or Cercospora leaf spot disease. Autumn leaf yellowing and drop is entirely normal in pomegranate; if it occurs in summer it indicates stress. Iron deficiency (chlorosis) in alkaline soils or compost causes the leaves to yellow between the veins while the veins themselves remain green (interveinal chlorosis); pomegranate is somewhat tolerant of alkalinity but can struggle in very chalky soils or when grown in compost with a high pH. Nitrogen deficiency causes a paler, more uniform yellowing of the older leaves. Overwatering and root rot cause yellowing that starts at the base of the plant and progresses upward; the leaves may wilt before yellowing. Cercospora leaf spot causes dark spots with yellow halos that merge and cause the leaf to turn yellow before dropping.

Q: Why is my pomegranate not flowering?

Pomegranate not flowering in the UK is most commonly due to insufficient sun, being grown in too much shade, being too young, or excessive nitrogen fertilising. Pomegranate requires a full-sun position to flower reliably; plants grown against a south-facing wall in full sun flower prolifically, while those in partial shade produce few or no flowers. Young plants, particularly those grown from seed, may take 3 to 5 years to reach flowering maturity. Excessive nitrogen fertilising promotes lush leafy growth at the expense of flowers; once a pomegranate is established, feed with a high-potassium fertiliser (such as tomato feed) in spring and summer rather than a high-nitrogen general fertiliser. Pomegranate also benefits from a period of relative dryness and cold in winter; plants kept too warm and moist throughout winter may not initiate flowering buds properly. Pruning in late spring or early summer removes the flower buds, which are carried on the current season's growth; any pruning should be done in early spring before new growth starts.

Pomegranate (Punica granatum) is a beautifully ornamental and surprisingly hardy exotic fruiting shrub that can be grown outdoors in sheltered UK gardens or as a striking container plant for the patio and conservatory. Its narrow, glossy leaves emerge in a bright coppery-bronze flush in spring before turning green, and its summer flowers are among the most vivid of any shrub grown in the UK. Leaf curling on pomegranate is most often caused by aphids on the new growth or by fungal leaf spot in wet summers.

Aphids

Aphids are one of the most common causes of curling new growth on pomegranate in the UK. They colonise the young, soft shoot tips and newly opening leaves in spring and early summer, clustering on the undersides of the leaves and at the growing points. Their feeding on the leaf before the tissue has fully expanded causes the leaves to curl under and inward as they develop; shoot tips may also distort and fail to extend normally. Heavy infestations can weaken the plant and cause premature leaf drop. Pomegranate is also attractive to whitefly and can host mealybug in conservatory conditions.

What to do

Pinch off and destroy the most infested shoot tips. Apply insecticidal soap or neem oil to the affected growth, targeting the undersides of the young leaves. Encourage natural predators by planting nectar-rich flowers near the pomegranate. Avoid high-nitrogen spring feeds, which promote soft growth that aphids favour. Already-curled leaves will not straighten but new growth will be undistorted once the aphids are controlled.

Leaf spot

Cercospora leaf spot (Cercospora punicae) and Alternaria leaf spot affect pomegranate in wet summers or in greenhouse conditions with poor air circulation. Cercospora causes small, round, purplish-brown spots on the leaf surface; the spots enlarge to pale brown or grey with a darker border and a yellow halo. Affected leaves curl, yellow, and drop prematurely; severe infections can partially defoliate the plant before autumn. Alternaria causes dark, water-soaked spots that expand and may merge, causing the leaf to crumple and fall. Both diseases are favoured by warm, humid conditions and overhead watering.

What to do

Remove and destroy affected leaves. Improve air circulation. Avoid wetting the foliage when watering. Apply a copper-based fungicide spray at the first sign of infection and repeat every 10 to 14 days in wet conditions. Collect and dispose of fallen leaves in autumn as they can harbour overwintering spores.

Powdery mildew

Pomegranate powdery mildew (Erysiphe punicae) appears as a white, powdery coating on the leaves and young stems. Affected leaves curl and distort, and in heavy infections may yellow and drop. Mildew on pomegranate is most prevalent in warm, dry summers with high day temperatures and cool nights, and in container plants where the roots are allowed to dry out; drought-stressed plants are significantly more susceptible to powdery mildew. The disease is purely superficial and rarely kills the plant, but repeated heavy infections over several seasons can weaken it.

What to do

Maintain consistent watering to prevent drought stress. Improve air circulation. Remove heavily infected leaves. Apply a potassium bicarbonate spray or a sulphur-based fungicide at the first sign of mildew. Avoid overhead watering in the evenings. A mulch around the base of garden-grown plants helps retain soil moisture and reduces stress susceptibility.

Drought stress

Pomegranate is notably drought-tolerant once established in open ground but will show leaf curl when grown in a container and allowed to dry out severely. The leaves curl upward and inward along their length (the opposite direction from aphid-induced curl); the plant may also wilt before rehydrating when watered. Container-grown pomegranates can dry out quickly in a hot summer and may need watering every 2 to 3 days. Garden-grown pomegranates in very well-drained soil during a prolonged drought may also show curl but typically recover quickly once watered.

What to do

Check container-grown pomegranates daily in hot weather and water when the top 5 cm of compost is dry. Garden plants benefit from a deep mulch of bark or compost to retain soil moisture. Increase watering frequency during extended dry spells. Avoid allowing the compost to completely dry out, which stresses the plant and increases susceptibility to both mildew and aphids.

Frequently asked questions

Why are my pomegranate leaves curling?

Pomegranate (Punica granatum) leaves curl most commonly in the UK because of aphid infestation on new growth, Cercospora or Alternaria leaf spot, powdery mildew, or drought stress. Aphids colonise the young shoots and new leaves in spring and early summer, causing the leaves to curl under and inward as they develop; the shoot tips may also distort and bunch together. Cercospora leaf spot and Alternaria leaf spot cause small, round to irregular dark spots on the leaves that enlarge and merge; heavily spotted leaves curl, yellow, and drop prematurely. Powdery mildew causes a white or greyish powdery coating on the leaves, which curl and distort. Drought stress causes the leaves to curl upward and inward along their length.

Can I grow pomegranate in the UK?

Yes, pomegranate (Punica granatum) can be grown in the UK and is one of the more reliable exotic fruiting plants for sheltered gardens. Standard fruiting pomegranate tolerates temperatures down to about -10°C when established and planted against a warm, south-facing wall, making it viable in most of southern England and Wales. The ornamental dwarf 'Nana' makes an excellent container plant. Pomegranate flowers in summer with spectacular orange-red blooms and fruit can ripen outdoors in long, warm summers in the south of England. It needs full sun, a sheltered position, well-drained soil, and modest feeding.

Why are my pomegranate leaves turning yellow?

Pomegranate leaves yellowing most commonly indicates natural leaf drop (pomegranate is deciduous and sheds all its leaves in autumn, which is normal), iron or nitrogen deficiency, overwatering, or Cercospora leaf spot. Autumn leaf yellowing and drop is entirely normal; if it occurs in summer it indicates stress. Iron deficiency in alkaline soils causes interveinal chlorosis where the leaf yellows between the veins while veins remain green. Nitrogen deficiency causes a paler, more uniform yellowing of older leaves. Overwatering and root rot cause yellowing that starts at the base and progresses upward. Cercospora leaf spot causes dark spots with yellow halos that merge and cause the leaf to yellow before dropping.

Why is my pomegranate not flowering?

Pomegranate not flowering is most commonly due to insufficient sun, being too young, or excessive nitrogen fertilising. Pomegranate requires a full-sun position to flower reliably; plants grown in partial shade produce few or no flowers. Young plants grown from seed may take 3 to 5 years to reach flowering maturity. Excessive nitrogen fertilising promotes lush leafy growth at the expense of flowers; use a high-potassium fertiliser such as tomato feed rather than a high-nitrogen general fertiliser. Pomegranate also benefits from a period of cold and relative dryness in winter to initiate flowering buds. Any pruning should be done in early spring before new growth starts, as flowers are produced on the current season's growth.