Invasive alien plants in your garden: Plant indigenous plants instead

By Tshegofatso Napo – Directorate on Biodiversity Evidence: South African National Biodiversity institute

Gardening is a common activity in South Africa and around the globe. When gardening is done in a considerate manner, it is part of society’s wise response to biodiversity loss and climate change, two of the major global challenges. However, as gardeners we need to pay special attention on what we plant in our gardens and ensure that we do not contribute further to the introduction and spread of invasive plants. Invasive plants contribute significantly to environmental problems and cost governments and landowners enormously. Whether you are visiting or taking a walk in the botanical garden or tending your own lawn, it is impossible to deny that gardens are beautiful and have a certain universal appeal. There is something about the presence of gardens in our lives that brightens our world. Very much of this has to do with something inherent in human beings, an instinctive appreciation of nature. Therefore, gardening is so important to our lives and culture and gardens should be taken care of.

Invasive alien plants are plants introduced to the countries and they non-native to an ecosystem, they are a major threat to biodiversity, economic development, and human livelihood. Most alien plants are aggressive invaders, and they can penetrate and replace indigenous plants. They have negative impact on both agricultural productivity and natural ecosystems, and they have become a persistent problem in South Africa. Although many invasive alien plants were introduced to South Africa unintentionally and intentionally through agroforestry, horticulture, etc; a significant number of species escapes from our gardens and become established in the wild.

Why should they be removed?

Invasive alien plants are a major threat to biodiversity in water resources areas and grasslands potentially interrupting the fragile natural balance in the ecosystems. As we are dependent on biodiversity for water, food, wood, clean air, medicine and many more, it is very important that we protect these resources. Humans are consequently both purposely and inadvertently vectors for the spread of invasive alien plants across South Africa, and across the planet.

What can you do?

Firstly, learn and understand what plants are in your garden, are they indigenous to your area? If not, are they listed species? How to remove and discard alien plants in a responsible manor? Invasive alien plants threat is likely to intensify given continued human-induced disturbances, with humans not taking awareness of, and finding mitigative measures to their negative consequences. If new alien invasive plants are discovered before they are well established, eradication is possible and management costs can be reduced, therefore if an invasive plant is discovered from your garden, remove it to prevent spread using methods such as digging, flower head removal before seed set, or hiring a professional to apply herbicides to destroy the plant. If all fails, contact authorities in your area to assist.

When removing invasive plants, plants should not be placed in your backyard composter as the temperatures will not get high enough to kill the seeds or viable vegetative plant parts.Do not throw your garden or yard waste over your fence into natural areas, this has been proven as a way that invasive plants spread into natural areas. Any aquatic plants should not be dumped into natural waterways or ponds. The other best way to know what you are planting in your garden is to purchase native plants from reliable or trustworthy suppliers and always keep their contact details for future enquiries should need be. Attend and participate in environmental education activities in your area to gain deeper understanding of environmental issues.

Examples of plants to avoid and  alternatives to grow.

Did you know that there is quite range of environmentally friendly, native plants that can be grown instead of the destructive, water consuming invasive alien plants growing in our gardens? Here are some suggestions:

Invasive and destructive species	Native and environmentally friendly species
Equisetum hyemale (snake grass) © Tshegofatso Napo	Equisetum ramosissimum (branchedhorsetail) © Johan Wentzel
Iris pseudacorus (yellow iris) © Mbali Mkhize	Moraea huttonii (large golden vlei moraea) © Fiona Hellmann
Tecoma stans (yellow bells) © Mbali Mkhize	Tecomaria capensis (cape honey suckle) © Peterjlor
Nymphoides peltata (yellow floating heart) © Margrit	Nymphoides indica (water snowflake) © Jeffrey Mapila
Nymphia mexicana (yellow water lily) © Christa Leroux	Nymphia capensis (cape blue waterlily) © Fredbont
Vinca major (greater periwinkle) © Dave Richardson	Plumbago auriculata (cape leadwort) © Tshegofatso Napo
Hedychium gardnerianum (kahili ginger) © Mariskadw	Strelitzia juncea (rush-leaved strelitzia) © Tshegofatso Napo
Harrisia martinii(torch cactus) © Hildegard Klein	Aloiampelos ciliaris (common climbing aloe) © Alex Wirth

References

Ewel, J.J., O’Dowd, D.J., Bergelson, J., Daehler, C.C., D’Antonio, C.M., Diego Gomez, L., Gordon, D.R., Hobbs, R.J., Holt, A., Hopper, K.R., Hughes, C.E., LaHart, M., Leakey, R.R., Lee, W.G., Loope, L.L., Lorence, D.H., Louda, S.M., Lugo, A.E, McEvoy, P.B., Richardson, D.M. and Vitousek, P.M. 1999. Deliberate introduction of species: research needs. Bioscience 49: 619–630.

Henderson, L. 2001. Alien weeds and invasive plants: A complete guide to declared weeds and invaders in South Africa. Pretoria: Plant Protection Research Institute South Africa.

Poona, N. 2008. Invasive Alien Plant Species in South Africa: Impacts and Management Options. Alternation 15(1): 160–179.

Powell, J. 2020. Grow me instead: Guide for Southern Ontario. 3^rd edition.