By Emily Heaton and Nicholas Boersma, Department of Agronomy
Giant Miscanthus (Miscanthus × giganteus) is a perennial warm-season grass used for bioenergy, and is being planted on thousands of acres in Missouri and Arkansas this spring. Given the warm spring, and the high level of interest in Miscanthus this year, we have been getting lots of questions around propagation and planting.
A sterile hybrid, Giant Miscanthus is most commonly planted from rhizome pieces when the soil temperatures have reached 50 F. Most farmers get their rhizomes from a commercial supplier, but those people who just want to play around with the new crop have been planting small plots that they can then dig up and propagate into larger stands at their leisure. Here are some things to consider if you are propagating and/or planting rhizomes this spring.
- If you want to dig up rhizomes from an established stand, it is best to do this while the stand is dormant, that is, after it has died back in the fall and before in emerges in the spring.
- If you are not replanting immediately, dig and separate the rhizomes, then keep them cool (approximately 40 F), making sure they don't dry out.
- If your Miscanthus has already emerged, you can still dig, but if you have expanded leaves, it is getting too late. Once the shoots get over 10 inches tall on average, you will start losing plants, and it is best to wait until the following year to dig. A rule of thumb might be that for every inch the stand is over 8 inches, you will lose 5 percent of the potential plants.
- Plant rhizomes in a weed-free row (can use strip tillage), making sure that all of the rhizome is covered, but not too deep; at least part of it should be within 2 inches of the soil surface.
- Good weed control is essential at establishment. Planting on a grid will allow for cultivation after the Miscanthus has emerged. Harness and Harness Xtra are labeled for use on Miscanthus for pre-emergent weed control.
- Rhizomes can take a while to emerge, anywhere from three days to three weeks, typically, with some not emerging until late in the season. This is frustrating, but resist the urge to dig anything up or replant until three weeks, warm temperatures and some good rain have had a chance to work.
Shoots of Giant Miscanthus emerging from a clump of rhizomes in a recently tilled field near Ames, Iowa. Most shoots are still in the whorl, with only a few small emerged leaves. Once more leaves have unrolled, this field should not be divided this year.
Emily Heaton is an Iowa State University agronomy professor with extension responsibilities in biomass production. She can be contacted by emailing firstname.lastname@example.org or calling 515-294-1310. Nicholas Boersma is a research associate in the agronomy department. He can be contacted at email@example.com or calling 515-851-1024.