Indiangrass
Sorghastrum nutans
also called indian grass, yellow indiangrass
The third pillar of the tallgrass prairie beside big bluestem and switchgrass: upright blue-green blades and feathery bronze-gold plumes glinting copper in the low September light.
- Type
- Grass · Perennial
- Botanical family
- Mixed / other
- Foliage color
- Blue-green · Bronze, red and brown
- Sunlight
- Full sun
- Watering
- Low once established
- Soil
- Any drained soil; deep prairie loam to poor clay
- Feeding
- Gentle all-organic
- USDA zones
- 4a–9b
- Frost tolerant
- Yes
- Sow direct
- at the last spring frost
- Plant out
- at the last spring frost
- Plant spacing
- 23.6 in
- In-row spacing
- 19.7 in
- Between rows
- 2 ft 6 in
- Square-foot density
- Not suited to SFG
- Sow depth
- 0.4 in
- Root system
- A dense fibrous mat
- Working depth
- 24 in–6 ft
- Can reach
- 8 ft down where the soil allows
- Spread
- 24 in–4 ft across, about 1–2× the width of the plant
- Shallowest pot
- 12 in of soil
Thousands of fine roots knit the top of the soil into a turf, which is what holds a bank together and what makes an established clump so hard to lift. Prairie grasses send a few roots far below the mat as well.
Prairie roots, two metres of them, which is what carries it through a drought and what makes it worth planting where the soil needs building rather than only where it looks well.
Figures recorded for Indiangrass itself. Roots follow the soil either way: a compacted pan, a high water table or heavy clay stops them well short of any of it, and deep open ground lets them go further.
- When
- Not harvested, except seed heads for the vase in September. Cut the stand down in late winter.
- What to look for
- Plumes fully bronze and glinting; for the cutdown, late March, before the new blades rise.
- How to harvest
- Cut dried stems for arrangements when the plumes glint copper. In March, shear the whole clump to 10–15 cm with hedge trimmers and compost the straw.
- How often
- One cutting, one cutdown, per year. Leave it standing between the two: winter cover for birds is half its value.
- Storing the crop
- Dried plumes keep indefinitely in a dry vase.
- Generally trouble-free No notable pest or disease problems when grown in the right conditions — one of the easy ones.
A warm-season grass that does most of its growing in July heat: it looks like nothing until midsummer, then earns the year in ten weeks. Leave it standing all winter for the birds and the architecture, and cut it down in March.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com