Floral funeral tributes that spell out words such as “Dad” or “Gran” could be under threat after churches were urged to ban “floral foam” because it harms the environment.

The displays that commonly sit alongside coffins in hearses and are laid around a grave are created by inserting flowers into a lightweight, porous, plastic-based foam that has been cut into the shape of letters.

But churches have been encouraged to work with local florists to find other ways to create the displays, including “scrunched-up chicken wire”, because the foam is “hugely problematic from an environmental point of view”.

They are also being urged to reduce the use of flowers imported from abroad for weddings and funerals due to the carbon footprint, with an encouragement to opt for “locally sourced” flowers over “imported blooms”.

It forms part of the Church of England’s drive to become carbon-neutral by the end of this decade, having set a target of reaching net zero by 2030 through policies including a crackdown on the installation of new gas boilers in churches.

A motion to be presented to a meeting of the Church of England’s assembly, the General Synod, in London next month warns: “Floral foam is extremely hard to dispose of. Anyone who has used it is aware of the green dust microparticles released when handling it, and this is often washed down the sink … A single block of foam contains the same amount of plastic as ten carrier bags.”

Dame Sarah Mullally will give her first presidential address at the meeting after she formally takes up the role of Archbishop of Canterbury next Wednesday.

A document prepared by the Bishop of Dudley, the Right Rev Martin Gorick, entitled “Glorifying God Sustainably” warned that the foam is “widely used in churches and cathedrals”, noting: “When it becomes unusable, it is often put on the compost heap, but being plastic it does not rot down into healthy compost, but its microplastic beads pass into soil and leach into water courses, damaging wildlife.

“The lifespan of a block of floral foam is estimated to be between 400 and 500 years.”

He added that the Royal Horticultural Society had banned the use of foam at the Chelsea Flower Show and other events.

Gorick said: “Happily, there are alternatives for flower-arranging, including using scrunched-up chicken wire, making structures from twigs, or simply using taller vases.” He also suggested using pebbles, sand, moss, twigs or glass marbles, or a glass or metal frog — a tool that holds flowers in place.

The motion, which will be debated and voted on next month, calls on churches to source flowers locally and also “calls on cathedrals, churches and churchyards to eliminate the use of floral foam and all similar non-biodegradable and non-reusable products and techniques, while rediscovering traditional and environmentally-friendly methods of presentation and display”.

An explanatory document prepared for synod members by Jo Chamberlain, the church’s national environment officer, notes: “The foam can be cut into shape, making it especially convenient for floral tributes for funerals and for floral displays at weddings, which is particularly relevant for churches.”

She added: “If churches still have unused floral foam, it would be best practice not to use it. Green dust is created when it is handled, spreading the dangerous microplastic particles. It should never be put into the compost. Even flowers and foliage that have been stuck into floral foam should not go in the compost bin because of the bits of floral foam sticking to the stems. Floral foam can only be disposed of in landfill.”

Several florists expressed caution over a ban but said they were working to find more eco-friendly options.

Jamie Grant, director of the British Florist Association, said: “While alternatives do exist and are already being adopted in many settings, they are not yet universally practical or accessible for every design or florist. The BFA is actively engaged in researching viable alternatives, working with manufacturers and florists.”

Fiona Hallam, a florist at AW Lymn funeral service, said that biodegradable alternatives “tend to be more fragile and lack the range of frame shapes needed for custom tributes.“

She added: “On top of that, they’re significantly more expensive, which could impact families already facing the rising cost of living.”

Hallam said that the funeral industry would support “innovation to ensure that any transition away from floral foam does not compromise on quality or affordability of the funeral tributes”.

Nicky Wylie, national chairwoman of the National Association of Flower Arrangement Societies (Nafas), said that his members used “a wide range of traditional and contemporary techniques that do not rely on non-biodegradable materials”.

She said: “Lettered funeral tributes such as ‘Dad’ or ‘Gran’ can be, and frequently are, created using methods including mossed bases, wire frames, reusable mechanics and natural materials, depending on the design and setting.”