Nutgrass (Cyperus rotundus) remains a persistent challenge for gardeners, particularly in Queensland, where its underground tubers, commonly referred to as “nuts,” complicate eradication efforts. According to local horticultural experts, the weed’s extensive network of subterranean stems carrying these nutlets can survive for more than a decade, and plants can regenerate from depths of up to half a metre. Gardeners attempting physical removal by digging often inadvertently stimulate further growth by disturbing dormant tubers.

Chemical control options include systemic herbicides such as glyphosate-based products like Roundup and Zero. Effective application requires high doses during the weed’s flowering phase to ensure translocation of the herbicide to the underground tubers, often necessitating multiple treatments. Halosulfuron-methyl, found in products like Sempra and Sedgehammer, is also effective but has strict usage restrictions. It is registered for application by professionals only and must be applied before the plant reaches the five-leaf stage. Both glyphosate and halosulfuron-methyl treatments perform better when used with a surfactant to enhance herbicide penetration.

Home gardeners are cautioned that halosulfuron-methyl is not suitable for use in home gardens due to plant-back limitations on many horticultural crops. For lawn treatment, formulations specifically targeting nutgrass, such as Searles Paspalum, Nutgrass and Clover Killer, may be more appropriate.

Separately, guidance is available for those interested in growing macadamia trees from seed. Successful germination requires freshly harvested nuts left in their shells, soaked overnight in warm water, then planted about 1 cm deep with the small white dot on the shell oriented sideways. The seeds should be kept moist in a warm, sunny location. Germination times vary widely, sometimes taking several weeks to months. Seed-grown trees typically differ from their parent plants and require six to eight years before producing fruit.

For more predictable traits and earlier cropping, gardeners may opt for grafted macadamia varieties, of which numerous selections are available from specialist nurseries and suppliers. These varieties offer known characteristics including tree size, flower colour, and crop timing. Cross-pollination between different varieties is also recommended to increase nut size and yield.