An excerpt from the Frequently Asked Questions document about Japanese Knotweed in Ireland on NBDC website;

Is Japanese knotweed a regulated species in Ireland?

under Regulation 49(2) any person who plants, disperses, allows or causes to disperse, spreads or otherwise causes to grow Japanese knotweed or any of the other invasive plants listed in the Third Schedule of the European Communities (Birds and Natural Habitats) Regulations, 2011 (S.I. No. 477 of 2011) shall be guilty of an offence. Furthermore, Sections 52(7) and (8) of the Wildlife Act, 1976, as amended,make it an offence to plant or otherwise cause to grow in a wild state exotic species of plants. (Section 52(7) and (8) of the Wildlife Act, 1976, as inserted by 56(d) of the Wildlife (Amendment) Act, 2000.Regulation 49(2) of the European Communities (Birds and Natural Habitats) Regulations, 2011 (S.I. No. 477 of 2011).

I have Japanese knotweed on my land, do I have to get rid of it?

you should take action to control and eradicate this plant from your site. By doing nothing it could be considered an offence by ‘allowing’ it to be dispersed or spread. It also makes sense to try and control and eradicate the plant from the site sooner rather than later as the longer it is left to expand and spread, the more resources will be required to deal with it.

Japanese knotweed is growing near my house, should I be concerned?

In most instances, Japanese knotweed and the other invasive knotweeds are growing far enough away from a house for it not to be an imminent threat but one that should be dealt with before it spreads closer to your home. If you can see Japanese knotweed growing above ground and within about 10 meters of your house then you should seek expert advice on assessing the risks to your home. While the rhizomes (underground part of the plant) are said to grow out to about 7 meters horizontally and 3 meters vertically, in reality this tends to be much less. However, spread of rhizomes beyond 7 meters has been documented where an easy route such as along ducting is available.

There is an infestation of Japanese knotweed on a neighbouring property and it is spreading into my land, who is responsible to get rid of it?

The landowner is responsible to ensure that they are not causing or allowing it to be dispersed or spread and should take action to control it. It is an offence for anyone to cause or allow it to be dispersed or spread. (see legislation in question 1)

Will having Japanese knotweed in a garden prevent selling a property or getting a mortgage?

While there are no known cases of mortgage applications being denied due to the presence of Japanese knotweed on site (as has occurred in Northern Ireland and England), having Japanese knotweed on the site can and has deterred some from purchasing a property. However, seeking professional advice on the actual level of threat should be sought.

Can anyone spray herbicide on Japanese knotweed?

No. Under the Sustainable Use of Pesticides Directive there are restrictions on use and application of herbicides by professional and amateur users. For further information see:

I’ve sprayed Japanese knotweed with glyphosate for the past 3 consecutive years and this summer year there is no visible re-growth, is the plant dead?

While there is no obvious above ground growth of the plant, the below ground rhizomes might still be living. If you do not need to disturb the site where the plant is, you should continue to monitor the area for several years and treat any re-growth.

There is Japanese knotweed growing in my community, who should I tell?

If possible, notify the land owner of the presence of the plant and its potential impact. If the plant is on public property you should inform the city or county council. Also submit the sighting details to the National Biodiversity Data Centre noting where it was seen and include a photograph if possible.

Where do I dispose of Japanese knotweed off site?

Japanese knotweed can be disposed at a deep-fill licenced landfill site. It is advised that you first check with the landfill if they can and will accept the waste. They may require notice to prepare to accept the waste.

Do I need to apply for a licence to move Japanese knotweed material or infested soil or spoil off site?

Yes. It is advised that you apply for a licence from National Parks and Wildlife Service. Only a licenced waste carrier can legally transport the waste to the landfill.