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Take care when composting some plants

Cutting back the borders and tidying up shrubs and bushes produces lots of material for the compost bin.
Much of it can go straight in to your home compost bin, some is best shredded or chopped first but the stalks and leaves of a few plants can cause you problems because they are toxic.
We all know to wear gloves and long sleeves when handling nettles or thistles but there are other plants that can cause skin irritation or an allergic reaction
Shredding safelyPlants with irritant sap. The most commonly encountered are Euphorbias, Daphnes, Hellebores and Aconitums like Monkshood and Wolf’s Bane.
Always wear gloves and long sleeves when handling, chopping or cutting back these plants. People vary in their sensitivity, but you should be careful not get the juice or sap on your skin. If you do – wash immediately with plenty of soapy water. Be particularly careful not to get sap in your eyes or to touch your eyes or face with gloves that have been exposed to the sap. If you do get sap in your eye immediately wash for at least 10 minutes with clean water.
If shredding stalks of any of these, wear gloves and goggles as you would anyway, and something that covers your arms and neck.

The sap of Lesser Hogweed, Heraclium sphondyllium, as well as of Giant Hogweed, Heraclium Mantegazzanium causes phytophotodermatitis. It does not directly irritate your skin but makes it super sensitive to sunlight so that your skin burns and can remain sore and red for several days. Be particularly careful to cover your neck and arms when strimming areas where Lesser Hogweed grows, as well as, of course, wearing a vizor.
Garden rue, Ruta graveolens, causes severe phytophotodermatitis. The redness and blistering can take a day or two to develop and can last for several days. Areas of skin burnt in this way can remain extra sensitive to sunlight for years. Wear thick gloves, or, better still, gauntlets.

Wash your secateurs after using them on any of these plants to avoid contact with any sap remaining on the blades.

Once composted, the toxins in all of these plants will have broken down and the compost can safely be handled and used in the garden - even on the vegetable plot.

Two types of Laurel, Cherry Laurel, Prunus laurocerasus, and Portugal laurel, Prunus lusitanica, contain cyanogenic glycosides. Their fresh leaves have the potential to form and release cyanide when damaged. So always prune, trim or shred these on a windy day to quickly blow away any of the harmful gas. If taking a load of prunings to a Recycling Centre, transport them in a trailer or keep all the windows open if you have to have them in the car.
Evergreens of this type take a long time to compost, so make a separate heap for them and leave to rot down for at least 3 years.

With sensible precautions, all these plants can enrich the compost you make.

Rhubarb leaves and potato leaves are poisonous if eaten, though we safely eat other parts of the plant when cooked. It is completely safe to compost these leaves and the resulting compost will be safe to use.

A small number of plants pose a risk to the environment
The worst is Japanese knotweed (Fallopia japonica), this spreads relentlessly from the tiniest piece of root and disposing of a large quantity is a job for a specialist contractor as it is classified as hazardous waste. A small amount could be burnt in an incinerator, not on a bonfire in contact with the soil, if your local regulations allow.

There are 5 plants covered by the Weeds Act 1959, Spear Thistle (Cirsium vulgare), Creeping or Field Thistle (Cirsium arvense), Curled Dock (Rumex crispus), Broad-leaved Dock (Rumex obtusifolius) and Common Ragwort (Senecio jacobaea), that are legally defined as injurious and that it may, in certain circumstances, be an offence to allow to seed and spread.
These are all native plants and, therefore, not the same as invasive aliens that are covered by The Wildlife and Countryside Act 1981or the new EU Regulation 1141/2014.

Common Ragwort is sometimes seen as a particular problem because it is highly toxic to horses and some other mammals but it is perfectly safe to compost it in a home composter sited where leachates cannot escape in to any watercourse if
- the compost bin has a lid so that any seeds cannot escape. Remember that ragwort can ripen seeds even after it has been pulled or cut
- plenty of grass mowings or other sappy material is incorporated with the ragwort so that the material quickly reaches a high heat
- the ragwort is left for a minimum of 12 months so that it is completely composted
The toxic alkaloids that ragwort contains are broken down by the composting process.
See The Scottish Government Guidance on how to prevent the spread of ragwort.