How to Grow Big Bluestem
Andropogon gerardii
Big Bluestem is the iconic tall prairie grass, growing 150-200 cm and known as the "monarch of the prairie". The upright blue-green foliage turns magnificent mahogany-red in autumn and the distinctive three-branched seed heads resemble a turkey's foot. Plant in spring in full sun and well-drained soil, even poor or clay. Space plants 75 cm apart. Water regularly in the first season to establish the deep root system; after that it is highly drought-tolerant. Do not fertilise. Never cut back in autumn. Cut to 15 cm in late February before new growth begins. Divide congested clumps every five to six years in spring.
Yearly Lifecycle
Care Essentials
Not needed. Big Bluestem is a prairie native adapted to poor soils. Feeding encourages weak, floppy growth and reduces the mahogany autumn colour.
Watch For
- Rust in humid conditions
- Lodging in rich soils
- Leaf spot
Companions
Echinacea, Rudbeckia, Liatris, Ratibida
Care Requirements
Light
Full sun essential
Big Bluestem requires at least six hours of direct sun daily. In shade it becomes floppy and fails to develop its characteristic upright form and autumn colour.
Watering
Drought-tolerant once established
Water regularly in the first season to establish the deep root system. Once established it is highly drought-tolerant with roots reaching 2 metres deep.
Fertilizing
Avoid feeding
Rich soils and feeding cause tall, floppy growth prone to lodging. Plant in poor to average well-drained soil and do not fertilise.
Pruning
Cut back to 15 cm in late February
Leave all old growth standing through winter. Cut to 15 cm above ground in late February or early March before new shoots emerge.
Mulching
Light mulch after spring cut-back
Apply a thin layer of bark or compost after cutting back. Avoid mulching heavily against the crown.
Growing Tips
The monarch of the prairie
Big Bluestem was the dominant grass of the tallgrass prairie, growing up to 200 cm. Its deep roots make it supremely drought-tolerant and an excellent soil stabiliser.
Turkey foot seed heads
The distinctive three-branched seed heads resemble a turkey's foot and appear in late summer. They persist through autumn, adding architectural interest.
Spectacular autumn colour
The blue-green summer foliage transforms to deep mahogany-red in autumn, one of the richest colour changes of any ornamental grass. Leave standing all winter.
Divide every five to six years
Clumps slowly expand outward. If the centre becomes woody or dies out, lift and divide in early spring, replanting vigorous outer sections.
