Planting with a legume is another way to increase the nitrogen content in soil for johnsongrass. Harvesting Johnsongrass is cut for hay when flower-heads are still in the boot stage. Coarse stems dry slowly and thorough curing is necessary to produce good hay. Seeds are dormant when first mature and require a number of months to after-ripen. Even when they do not germinate completely until alternating cold-warm temperatures are available in a warm area.
Eradication is sometimes a serious problem.
Pasturing has been recognized as one method to control this grass. Mowing gives much the same effect. An average plant produced from a single seed can produce more than 170 culms, ca 20 m of rhizomes and 1.7 kg of seed per season, depending on soil fertility, moisture, and space. Frequent mowing or grazing through the growing season, exhausting the rootstock, is the best means of eradication. Seed yields may be small in some hybrids and cvs, up to 1.7 kg per plant.