How long does palmarosa keep yielding and is it worth replanting after a few years?

Palmarosa is a perennial that commonly stays productive for about 4 to 5 years, giving multiple cuttings each year, after which clump vigour and herb yield (and so oil output) tend to decline and replanting becomes worthwhile. The economics are attractive because you plant once and harvest for several years with low input, spreading the establishment cost. Over time, as clumps age and crowd, the per-cut herb yield drops and oil recovery can weaken, so you watch your tonnage per cutting and replant when it falls enough that a fresh stand would pay better. Good nutrition, weed control early on, and timely cutting keep yield up through the productive years. When you do replant, it is a chance to use improved planting material if your buyer wants a higher geraniol type. As always with these oil grasses, your actual return over the crop's life depends on grass tonnage, oil recovery, geraniol content and the oil price, all variable, so track your own numbers and replant based on declining real yield, not a fixed calendar. Keep the oil buyer and distillation arrangement in place across the whole cycle, and confirm price and spec in writing each season.