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Herbaceous Perennial

Agastache nepetoides
  • RHS Plants for pollinators

yellow giant hyssop

A tall perennial, up to around 2m high, with stout, square stems and aromatic, coarsely toothed green leaves up to 15cm long. Dense spikes of tubular, pale greenish-yellow flowers are produced in late summer

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Size
Ultimate height
1.5–2.5 metres
Time to ultimate height
2–5 years
Ultimate spread
0.5–1 metres
Growing conditions
Chalk
Clay
Loam
Sand
Moisture
Moist but well–drained
pH
Acid, Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Green
Summer Yellow Green Green
Autumn Green
Winter
Position
  • Full sun
  • Partial shade
Aspect

East–facing or South–facing or West–facing

Exposure
Sheltered
Hardiness
H3
Botanical details
Family
Lamiaceae
Native to GB / Ireland
No
Foliage
Deciduous
Habit
Columnar upright
Genus

Agastache are herbaceous perennials with simple, aromatic leaves and small 2-lipped tubular flowers in whorls forming dense spikes, in summer and autumn; some are rather tender but can be grown as annual bedding

Name status

Correct

Plant range
E Canada, Central USA

How to grow

Cultivation

Thrives in fertile, moist but well-drained soil in sun or light shade. Dislikes summer drought

Propagation

Propagate by seed or by division in spring. Will self-seed in place in good conditions

Suggested planting locations and garden types
  • Architectural
  • Cottage and informal garden
  • Wildlife gardens
  • Flower borders and beds
Pruning

Remove spent flowering spikes as they fade

Pests

Generally pest-free

Diseases

May be susceptible to powdery mildews

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