Which flowers last longest in a vase, and why

How long common flowers typically last

These are typical figures for flowers bought in good condition and kept in a cool room with clean water and flower food. A sunny windowsill or a room next to the oven will cut them short, and a cool hallway can add days. The absolute numbers move with the conditions, but the order barely changes, and the reasons for that order are what help you choose.

• Potted phalaenopsis orchid: around 45 days of bloom, but this is a living plant with roots, not a cut stem.
• Chrysanthemum: around 16 days.
• Carnation: around 14 days.
• Lily: around 10 days for the stem, as its buds open in turn.
• Freesia: around 9 days.
• Sunflower: around 8 days, provided the water is topped up.
• Rose and hydrangea: around 7 days each.
• Tulip and iris: around 6 days.
• Peony: around 5 days, and fewer in a warm room.

Firm stems keep drinking for longer

Most cut flowers do not die because they run out of food. They die because water stops reaching the head. Bacteria multiply at the cut end and in the vase, and together with air drawn in at cutting they plug the fine vessels that carry water up the stem. Once enough of those vessels are blocked, the flower wilts even though it is standing in water.

Stems differ in how quickly that happens. Chrysanthemum and carnation stems are firm and fibrous, with comparatively little soft tissue at the cut end to break down and feed bacteria, and they hold their shape even when uptake slows. Soft, fleshy stems such as tulip and gerbera decay faster at the base, which gives bacteria an easy start.

Hydrangea looks sturdy but behaves differently. Its woody stem blocks readily, and its huge head of papery florets loses water fast, so it can collapse in an afternoon. The upside is that the florets also absorb water, which is why submerging or misting a wilted head so often revives it.

Some flowers ignore ethylene, others are undone by it

Ethylene is a gas that plants release as they age. It tells fruit to ripen and, in many flowers, tells petals to wilt or fall. Ripening fruit, cigarette smoke, exhaust fumes and rotting leaves all give it off, so a vase can be sitting in a steady dose without anyone noticing. How a flower responds depends largely on the family it belongs to.

The daisy family, which includes chrysanthemum and gerbera, is largely insensitive to it, and that is a large part of why chrysanthemums sit at the top of the cut-flower list. When they do decline, it usually shows first as yellowing leaves, while the flowers themselves stay presentable.

Carnations are the surprising case. They are highly sensitive to ethylene: an exposed carnation curls its petals inwards and closes up, a symptom growers call sleepiness. They last as well as they do largely because commercial carnations are routinely treated after harvest with an ethylene inhibitor, traditionally silver thiosulphate, which blocks the flower's response. Part of a carnation's long life is bred into it and part is added in the packhouse, which is also why one left beside a fruit bowl can fade surprisingly fast.

Orchids show how powerful the signal is. An unpollinated phalaenopsis flower can stay open for weeks, but pollination sets off a burst of ethylene and the petals wilt soon after, because the flower no longer needs to attract anything. Some lilies are sensitive too, and ethylene exposure can make their unopened buds shrivel or drop before they flower.

Many buds, opening one after another

A single bloom has a fixed life. A stem carrying a sequence of buds does not, because as the first flower fades the next is only just opening. Lilies are the clearest example: each individual lily flower lasts only a few days, but a stem with four or five buds opens them over several days, and snapping off each flower as it goes over keeps the whole stem looking fresh for well over a week. The figure for a lily is really a figure for the stem.

Freesias work the same way, opening progressively along the curved spike from the lowest bud upwards. Spray chrysanthemums and spray carnations spread their display across many small heads at different stages, so there is nearly always something opening.

Irises show the reverse. They open within a day of coming indoors and each bloom is short-lived, with little waiting behind it, which is why they sit near the bottom of the list despite being perfectly healthy flowers.

Slow burners and fast burners

A cut flower lives on the sugars stored in its stem and petals, plus whatever flower food adds. It uses them through respiration, and the faster it respires the sooner it runs out. Compact flowers with tough petals, like chrysanthemums and carnations, tend to work through their reserves slowly. Large, soft, fast-opening flowers spend them quickly: a peony can go from a tight ball to fully blown in a couple of days in a warm room, and there is no way to slow it down again once it has opened.

Temperature sets the pace for every flower. Respiration climbs steeply as a room warms, which is why the same bunch lasts noticeably longer in a cool spare room than beside a radiator, and why florists keep their stock in a cold room until it is arranged. Tulips add a twist of their own: they keep growing after cutting, stretching and bending towards the light, and that growth draws on the same limited reserves.

Sunflowers sit in the middle for a different reason. A thick stem and a heavy head drink a great deal, so they last well when the water is topped up daily and fade quickly when the level drops below the stem end.

Choosing flowers that will last as a gift

If the gift needs to last, perhaps for someone recovering at home or a person who will not think to change the water, those mechanisms translate into a few practical choices.

• For the longest display, choose chrysanthemums, carnations or a mixed bouquet built around them. They forgive a missed water change better than almost anything else.
• Ask for lilies in bud, with only the first flower showing colour, so the recipient sees the whole opening sequence instead of the end of it.
• For a gift meant to last weeks, a potted orchid outlasts any cut flower, as long as it is watered sparingly and kept out of direct sun.
• Send roses, tulips and peonies for what they are, not for how long they last. Expect about a week at best, and less in a warm house.
• Keep any bouquet away from the fruit bowl. Ethylene from ripening fruit shortens the life of carnations, orchids and some lilies in particular.

One caution about the longest-lasting cut flower of all. In much of Europe, white chrysanthemums are associated with mourning and are often placed on graves, so for a birthday or a thank-you to someone who grew up with that custom, coloured chrysanthemums or carnations may be the kinder long-lasting choice. In other traditions the chrysanthemum carries quite different, often very positive, meanings, and many families think nothing of it at all. It is worth a moment's thought about who will be opening the door.