No succulents present? Buy trays or sacks of cuttings on Etsy, suggested them, or adopt plants at the garden center – maybe those marketed in the houseplants department.

The first time I saw one of Ms. Tracey’s pumpkin and succulent arrangements, I thought the pumpkin had been hollowed out to serve as a vessel or to hold a glass of water. Not so: the arrangement was placed on top of the pumpkin after its stem was removed and then pinned and glued into a bed of sphagnum moss.

This idea isn’t limited to pumpkins. In the low glass bowls that Mrs. Tracey had used for the latest wedding centerpieces, she peeled off moss that had grown on paving stones and other stones in her garden, allowed it to air dry, and used it in place of sphagnum. But in a vessel, unlike a pumpkin, “you need something in the container under the moss to serve as a pincushion,” she said.

Flower foam was once the industry standard, but it contributes to microplastic pollution. In the UK, the Royal Horticultural Society recently banned its use at all flower fairs starting in 2021. Possible substitutes are a dense tangle of grapevines or fine twigs, bundled chicken wire or a cellulose sponge.

For the pumpkin project, you’ll need dry, long-fiber sphagnum moss, flower needles, spray glue, and sticky glue (a craft product), plus an assortment of succulents – and a pumpkin that has been cured rather than fresh the vine. Take the cuttings a few days in advance to give the cut ends time to air dry. Before assembling, create a rough design by arranging the cuttings on a flat surface.

After removing the pumpkin stem, apply spray glue to the top of the pumpkin and nestle moss on top. Attach the succulents to the moss with sticky glue and flower needles if necessary, starting with the larger elements. Sticky glue takes time to dry, so let the arrangement sit overnight before moving it.