As frost edges in and we start tidying up the garden for the colder months, many don’t realise that a seemingly harmless green waste bag could land them in serious trouble.

Gardeners across the UK are being warned that dumping certain plants, especially those classed as invasive species, could result in a fine reaching £5,000 or more.

According to waste management expert Ali Lijee of Rubbish.com, the rule of thumb is: if the species is invasive, you cannot just chuck it in the green bin and forget about it.

“In the autumn and winter, when we clear out over-grown beds, pull up summer perennials and rake leaves and stems, the temptation to bag everything and hand it to the council is high, but wrong disposal could cost you dearly.

“While many local councils publish their garden-waste guidelines online, the tricky bit is recognising what goes in the bin and what doesn’t. Specifically, plants that are classed as invasive non-native species must be handled with care, or legal consequences may follow.

“For example: Japanese knotweed, Giant hogweed, Himalayan balsam, Rhododendron ponticum and New Zealand pygmyweed are all on the Government’s list of restricted species,” the expert revealed.

Lijee explains: “In autumn you might be clearing out the old border, chopping down last year’s foliage, disposing of pond plants or dead shrubs, with lots of potential to make a mistake. If you toss in material from one of the listed species you risk not just a fine but possible prosecution.”

In England and Wales, legal guidance states that you must not “import, keep, breed, transport, sell, grow, cultivate or allow to reproduce” any of the listed invasive alien plants. That means even if you found the plant in your own garden, you cannot simply bag it up as general green waste and send it off.

If local collections discover such material in a garden waste bin, the consequences vary: an initial contamination — for example, dumping soil, pet waste or food waste in the garden-waste stream — may result in a warning or smaller fine (for example, around £100).

But if you repeatedly ignore the rules, or if you’ve disposed of invasive species incorrectly, the fine can climb to £5,000 (and for companies even higher). In the worst-case scenario you could even face prosecution for environmental harm.