Property Care Association Property Care Association

Gardeners - Tackling Invasive Weeds & Plants

If you look after parks and gardens in a professional capacity it is likely you will come across non-native invasive weeds and plants on a regular basis.  As such it is probably a good idea to make sure you recognise some of the commoner invasive species.

Determining if it is an invasive weed in the garden

Anyone offering professional services has a ‘duty-of-care’ to their clients so it is a good idea to make sure you recognise common invasive plant/weed species, at least those which have, potentially, the most impact (physical, environmental, economic).  

If you are looking to improve your knowledge, we have compiled a useful summary of all the invasive weeds/plants species..  

If however, you suspect a plant may be an invasive species, but need confirmation or reassurance, most of our Invasive Weed PCA members are happy to provide some on-line guidance if you supply photographs. To find one locally, you can use our ‘find a local PCA specialist’ tool.

Alternatively, if you wish to brush-up or improve your non-native species identification skills you might be interested in our invasive plant identification course

Invasive plant ID course >>

Find a local specialist >>

What to do if you come across invasive plants or weeds

Armed with the knowledge that you or your client have an invasive weed or plant species to ‘manage’ within their garden - what do you do next?  

The 1st thing to do

The first job is to establish the extent of the invasive weed infestation and what needs to be done immediately to prevent further spread on or off site.  This is called a biosecurity plan. (note: more information about biosecurity plans via the 'Code of Practice') 

This is more challenging for some invasive weed/plant species than others. For example, Japanese knotweed may be one of the most difficult invasive weeds to control, but only spreads by vegetative means.  For Japanese Knotweed, biosecurity measures could be as simple as creating a cordon to prevent soil disturbance and some warning signage with a brief explanation.  

The above may sound relatively easy, but you also must consider that wildlife such as badgers, rabbits and foxes don’t read, so a bit of mesh fencing is normally recommended too!  A biosecurity plan should also include considerations about infestation risks from the surrounding area e.g. if there is more knotweed nearby but not on your client’s land.

The 2nd thing to do

Perhaps your most significant ‘duty’ is to recognise invasive weeds which may be harmful to health e.g. Giant Hogweed.  This a few other umbellifers (e.g. Poison hemlock, Wild carrot; albeit these latter species are not ‘listed’) are potentially harmful to humans (and some other animals like dogs) by skin contact.

Clearly, if Giant Hogweed is present, the biosecurity advice above applies (albeit the risk of spread is more generally due to seed dispersal) but you should make it clear to the client that due to the additional risks to human health, if public access is possible or likely, treatment or removal ought to be considered urgently. 

Garden use & considerations before managing invasive plants

Beyond these preliminary matters your key responsibility is to establish your clients needs for the garden or park etc. This will usually drive the selection of the optimum invasive weed management plan and PCA members can guide you through the options available, the consequences for land use in each case and, importantly, budget considerations. Key considerations will be things like whether the area is likely to be disturbed (for landscaping or routine maintenance e.g. hoeing, adding/removing bedding plants etc.).

Controlling/Managing the invasive issue in the garden

Managing invasive weeds is a job that requires careful planning and will normally involve interventions lasting several years followed by an even longer monitoring period (checking for signs of re-growth or new infestations).  

The practical aspects, getting ‘on-top of’ the invasive weeds found, usually involves two approaches (separately or together) that professional gardeners will be familiar with: 

  1. herbicide treatment* or
  2. digging/excavation.  

However, selecting the best approach requires a degree of familiarity with the characteristics of each species.  Fortunately, the PCA has published a book (Practical Management Guide) based on our members’ experience and this may enable small jobs to be tackled confidently.  

There may however, be many situations in which the best advice for your client is to engage with a local PCA member who can provide an Invasive Weed Management plan fully compliant with the principles of Integrated weed control.  All our members work to The Amenity Standard and can offer long-term guarantees backed-up by appropriate insurance if required for e.g. mortgage purposes. 

PCA members can guide you through the options available, the consequences for land use in each case and the likely costs. Key considerations will be things like whether the area is likely to be disturbed (for future landscaping or routine maintenance e.g. hoeing, adding/removing bedding plants etc.).

*Alternatives to herbicide treatment for managing plants in situ are available; these include, for example; heat treatments, bio-control and cultural techniques but using these methods is still somewhat experimental as far as most invasive weed species are concerned. A recent blog on Integrated Weed Management Plans and invasive weed management is - here (link).

Technical documents you can view

For those interested, there is a variety of invasive weed related 'Codes of Practice', Technical Documents, Guidance Notes and other related documents via our 'Invasive Weed Control Document Library'.  Simply click on the button below to view the library.  Documents of interest include:

  • NEW – Herbicide Treatments and Japanese knotweed – PCA Guidance Note
  • Restrictions on the Use of Herbicides on Hard Surfaces
  • Root Barrier and Japanese Knotweed Remediation
  • Waste Classification for Works in a Commercial Setting
  • UPDATED – List of Invasive Non-Native Plant Species

Visit the document library >>

Learn more - Free CPD videos on invasive weeds

Want to learn more about invasive weeds & plants?

For those interested in learning more about invasive weeds and plants, there is a variety of PCA training options for surveying professionals as well as technical/trade professionals. 

Use the search tool below to find available invasive weed related training courses or simply go to our training & qualifications section.  Alternatively, if you want to chat to someone, contract our training team on 01480 400 000 or contact them online.

More about training >>

Contact us >>

Search Courses

More about PCA Membership 

Interested in taking part in the CPD scheme but you are not a PCA member?  Find out more about membership and why it will benefit you!

Find out more >>

Professional Guidance

For those professionals looking for information, technical help and guidance towards and variety of property related problems, why not check out our 'professional guidance' pages.

Find out more >>

The Property Care Association
11 Ramsay Court
Kingfisher Way
Business Park
PE29 6FY

Content Copyright © 2024 Property Care Association - All rights reserved. The Property Care Association is a company limited by guarantee and registered in England: No. 5596488

“PCA®” and the PCA logo are registered trademarks of the Property Care Association. Legal Information and Disclaimer.