Freesia plants are widely grown in gardens across the world for their flowers. The plants are native to South Africa. The species Freesia alba x leichtlinii has escaped domestic cultivation and has began to establish itself as a noxious weed in many locations throughout Australia. The perennial plant competes with native orchids and seriously threatens their well-being, according to the Environmental Weeds Action Network. The plant is difficult to control because it produces seed and corms to propagate. Control may take several years to obtain in a large, widespread infestation area.
Hand dig areas of mild freesia infestations. Use a garden trowel and dig deeply around the plant to remove the corms. Pull all areas of the tuberous root system free from the soil. Promptly dispose of the freesias. Replant the area using native plants or garden plant choices that are not noxious. The ideal time to dig up the freesia is between August to September before the root system is firmly established.
Look closely at the area where the freesia was growing to make sure that all berries of the plant have been removed. Handpick each one out of the soil. Sift the soil between gloved hands to locate any that might be loose.
Cut all the plants foliage to ground level between July to September for complete control and to avoid letting the plants set seeds.
Spray the freesia during flowering using glyphosate or metsulfuron methyl. Mix the herbicide according to the directions on the label. Spray using a hand-held garden pump sprayer. Take care when spraying the freesia to not inadvertently hit other plants because they will be damaged or killed by the herbicide. Avoid spraying the freesias on a windy day when the herbicide can be spread to surrounding plant life.