How to identify and remove giant Hogweed and Australian Swamp Stonecrop

Over the past weeks, we have touched upon a variety of invasive species which might wreak havoc in your garden. In this article, we wanted to talk about Giant Hogweed and Australian Swamp Stonecrop, two plants which thrive in damp hotspots.

Giant Hogweed

Giant Hogweed (Heracleum Mantegazzianum) is an invasive non-native plant species. It was introduced to Britain as an ornamental in the 19th century. Giant Hogweed has a reddish-purple stem with fine spines that make it appear furry, much like a stinging nettle, and flowers in June and July. What is interesting to know is that Giant Hogweed has seeds that can stay in the soil for several years before they develop, so you might not be aware that it has even invaded your outdoor space.

Removing Giant Hogweed can be quite dangerous as the sap is harmful to humans and can cause severe skin blistering and scarring. If the sap gets into the eyes, it has been known to cause blindness. Full PPE should be worn during any management techniques or if working near the plants to prevent contact with eyes or skin. The best ways to remove Giant Hogweed is by cutting, herbicide treatment or burial but we would always advice getting in touch with an expert.

Australian Swamp Stonecrop

The Australian Swamp Stonecrop (Crassula Helmsii) is an invasive species that is commonly found in slow-flowing freshwater habitats, where it thrives and grows all year round.

The aquatic weed can be found in three forms:

1. A terrestrial form with creeping stems and aerial, succulent leaves.
2. An emergent form with densely packed stems, found in water less than 0.6m deep.
3. A submerged form that grows from a basal rosette with long, sparsely leaved stems reaching the surface.

It is vital to manage this weed early to be successful in eradicating it quickly – the older the colony the more difficult it is to remove it.

Glyphosate is recommended as a herbicide treatment to eradicate the emergent growth. We recommend staying clear of cutting as it isn’t always useful, however dredging can be beneficial due to the shallow rooting of the weed.

If you need expert advice on removing invasive species, be sure to check out this article on our website https://terraqua.co.uk/control-nuisance-aquatic-plants/