June 2023 Culture, Variety Info
Culture Report: Sorghastrum ‘Golden Sunset’ By Cary Levins

A bright new Indiangrass that shines for its earliness.

Sorghastrum ‘Golden Sunset’ is a gorgeous earlyflowering form of Indiangrass originally selected at Minnesota Landscape Arboretum. With its full, densely packed golden burnished bronze plumes held high above wide, olive-green blades and its tight, upright habit, this cultivar is a striking addition to any garden.

We have tested ‘Golden Sunset’ at both our northern (Pennsylvania) and southern (Florida) trial gardens, and it far exceeded our expectations. It flowers extremely early, long before other Sorghastrum nutans. Late summer is the typical timeline, but by late spring, ‘Golden Sunset’ is producing plumes. It’s hardy in Zones 3 to 10.

Another distinguishing characteristic: ‘Golden Sunset’ won’t open up or break open. The columnar, upright habit stays tight and true to form. At maturity, it can reach up to 60 inches and spreads to about 2.5 feet. Plant in full sun.

TRANSPLANTING

Plant one plug per 1-gallon finished size. If you’re producing 2- or 3-gallon sizes, add one plug per pot size. Always choose a well-draining commercial medium. We like to use a preventive fungicide drench at planting. Plants will finish in eight to 10 weeks. This is a warm-season grass, so add a few weeks to the finish time if you’re planting in late winter or early spring outdoors.

GROWING TEMPERATURES

Again, this is a warm-season grass, so ideal greenhouse temperatures are 65 to 75° F during the day. Nighttime temperatures should be between 55 and 65° F.

SOIL PH AND ELECTRICAL CONDUCTIVITY (EC)

Maintain soil pH in the range of 5.8 to 6.2. Aim for soil EC levels between 0.8 and 1.2 mS/cm using the 2:1 extraction method.

FERTILIZATION

Feed ‘Golden Sunset’ with a slow-release fertilizer at 10 to 15 pounds of nitrogen per yard. If you’re using constant liquid feed, it likes low levels: 100 to 150 parts per million of nitrogen.

WATERING

Keep soil evenly wet, but allow it to dry between ample waterings. Sorghastrum has a medium tolerance to dry soil or drought.

LIGHT

Provide high light levels (5,000 foot-candles or more). Supplemental lighting generally isn’t necessary.

PINCHING & PGRs

‘Golden Sunset’ doesn’t need pinching or plant growth regulators; its naturally tight habit keeps its growth well controlled and maintained.

PEST AND DISEASE

As long as you’re following a monthly preventive broad-spectrum fungicide application program, plus scouting and monitoring regularly, pests and diseases shouldn’t be an issue. We didn’t have any at either our Pennsylvania or Florida trials. Best practices should include maintaining good air circulation and managing humidity levels.

OVERWINTERING

If you’re overwintering ‘Golden Sunset’, begin to cut back fertilizer levels as dormancy approaches. Do not stop fertilizer applications altogether. The idea is to stop the plant from producing new growth, but still allow the root system to add enough stores to get through winter. I like liquid feed for overwintering because it gives us the flexibility to adjust as needed. We suggest a preventive fungicide drench to prevent root rot. Before winter, cut them back — it’s less mess and labor for spring. If you’re in the South, they’ll overwinter just fine under cloth; if you’re up North, you can overwinter grasses alongside your perennials in cold frames.

For an enhanced reading experience, view this article in our digital edition by clicking here.