Drying flowers: air, silica and pressing

Drying works because a flower that loses its water slowly and evenly keeps most of its shape. Everything that goes wrong with dried flowers comes from one of two things: drying too slowly in a damp room, or choosing a flower whose petals were never going to survive losing their water.

Irish houses make the first problem worse than it is elsewhere. A back bedroom in October is exactly the kind of cool, still, humid room in which a bunch of roses goes furry rather than dry.

What dries well, and what does not

Reliable. Roses hold shape and darken a shade or two. Hydrangeas are the best of the lot and barely need any help. Gypsophila dries almost by accident and keeps its colour. Lavender keeps both colour and scent. Statice, strawflower, achillea, nigella pods, poppy seedheads and ornamental grasses all dry as if they were designed for it, because in a sense they were.

Workable with silica. Peonies, dahlias, ranunculus, anemones and open garden roses. All of them are too full of water to air dry cleanly, and all of them keep their shape well if the water is pulled out while the petals are supported.

Not worth attempting. Lilies, tulips, daffodils, gerberas, freesias, irises and orchids. Thick fleshy petals and hollow water-filled stems mean these go brown, translucent and limp rather than dry. A lily that has been hung to dry looks like something that has died rather than something that has been kept. If one of these is the flower that matters to you, press a single bloom flat instead and frame it, which is a different object but a good one.

Before you commit a whole bouquet, dry one stem of each type and look at it in a fortnight.

Air drying

The default method, and it costs nothing.

Strip the leaves. Leaves hold water, mould first, and look wrong dried. Bundle stems into groups of five or six, no more, with an elastic band rather than string so the bundle stays tight as the stems shrink. Hang them upside down somewhere dark, dry and moving with air. A hot press is the best spot in most Irish houses. An attic works in summer. A garage does not, because it is damp.

Dark matters more than people think: light bleaches the colour out over the two to three weeks the process takes. Airflow matters most of all, because still humid air is what turns a bundle mouldy from the inside.

Hydrangeas are the exception to all of this. Cut them late, when the heads have gone slightly papery, stand them in a vase with about 5cm of water and let the water evaporate away. They dry standing up, in the room, and keep a better colour than any hung hydrangea will.

Silica gel

Silica crystals are a desiccant. They pull the water out fast while the flower sits supported in them, which is why the result keeps its three dimensional shape and most of its colour.

Cut the stem to about 2cm. Put a 3cm layer of crystals in an airtight container, sit the flower head up on it, and spoon more crystals gently around and between the petals until the flower is buried and the shape is supported everywhere. Seal it.

Roses take four to seven days. Smaller flowers take three or four. Leaving them in much longer makes them brittle enough to shatter, so check on schedule rather than forgetting about them. Pour off the crystals gently and brush the last of them out with a soft paintbrush. If you need a stem, push florists' wire up into the base of the head before drying.

The crystals are reusable indefinitely: dry them in a low oven when they change colour. A bag costs about the same as one bouquet and will do a decade of them.

Pressing

Pressing gives you a flat object, so treat it as its own craft rather than a compromise. It suits single-layer flowers, ferns, leaves, sweet pea, pansies, cosmos, cornflowers and individual rose petals.

Between two sheets of plain paper, inside a heavy book, with more books on top. Change the paper after two days, because the first paper takes up most of the moisture and left in place it will mark the petals. Two to four weeks. Thick flowers can be split down the middle with a blade and pressed as two halves, which is how a full rose gets pressed at all.

Keeping a wedding or sympathy bouquet

Take it apart. This is the whole trick, and almost nobody does it.

A bouquet is bound tight at the stems with the heads pressed against each other, which is the exact arrangement that traps moisture at the core. Hung as it is, the outside dries and the middle goes mouldy, and you find out four weeks later.

So: photograph it from a few angles first, then cut the binding, separate the stems, sort them by what each one needs, and dry them by the right method. Roses and peonies to silica, gypsophila and lavender to air, foliage pressed or air dried. Rebuild it afterwards with wire and florists' tape, or, better, do not rebuild it at all and put the individual stems into a small vase or a shallow frame. A rebuilt bouquet rarely looks like the original, and the pieces usually look better than the reconstruction.

Timing is the other half. Start within three to five days, while the flowers are open and still firm. Waiting until a wedding bouquet has visibly gone over means drying flowers that are already halfway to brown.

For a sympathy bouquet the calculation is different, and it is worth saying that keeping one is not obligatory. Plenty of families would rather not have a dried arrangement in the house at all, and a photograph is a perfectly good record. If you do want to keep something, a few stems dried and framed flat is easier to live with than a whole preserved bouquet. See sympathy flowers for what Irish families usually do.

Looking after them afterwards

Dried flowers are finished, not immortal. Direct sunlight will take the colour out in a few months, and a bathroom or any humid room will soften them and let mould back in. Dust with a hairdryer on cold, from a distance. Expect two or three years from a dried arrangement before it looks tired, and a lot longer from hydrangeas and grasses.