How to revive wilting flowers

A drooping bunch has one of three causes, and the fix for each is different enough that guessing wastes the flowers. Spend a minute working out which one you have before you do anything.

Diagnose first

Air lock. The heads droop but the petals are still firm and well coloured, and the water in the vase is clear. This is the most common cause and the one most worth treating. Water is not reaching the top of the stem because a plug of air sits in the channel, usually drawn in when the stem was cut in dry air or left out of water on a worktop. Roses, gerberas, hydrangeas and any hollow-stemmed flower show it first.

Bacteria. The water is cloudy or smells, the stem ends are slimy or brown, and the lower leaves are yellowing. The blockage here is a colony rather than an air bubble. It is treatable if you catch it on the day, and it usually means the vase was not clean or the water has gone three or four days without a change.

Age. Petals are translucent at the edges, going papery, or dropping when the vase is nudged. Pollen has been shed. Lilies have gone from waxy to soft, roses have blown fully open and the outer petals lift away with no resistance. Nothing brings this back. The only thing to decide is what to keep and what to bin.

A quick test that separates the first two from the third: pinch the stem a few centimetres below the head. A stem that is still firm has a plumbing problem you can fix. A stem that gives softly under a fingertip has run its course.

Fixing an air lock

This works on most flowers and takes about ten minutes of your attention plus two hours of waiting.

1. Take the whole bunch out of the vase.
2. Re-cut two to three centimetres off every stem at a slant, under running water.
3. Fill a clean bucket or the sink with 15cm or so of cool water.
4. Stand the stems in it and leave them somewhere cool for two hours. Deep water and cool air together do more than either alone.

Most bunches lift within an hour. Put them back into a clean vase with fresh water and food afterwards, not back into the water they came out of.

The hot water method, for woody stems

Roses, lilac, hydrangea, blossom branches, chrysanthemums and other stems that feel hard rather than sappy respond to this and it is worth knowing.

Boil a kettle and pour about 5cm of water into a heatproof jug. Cut the stems fresh, wrap the flower heads loosely in a tea towel or paper so the steam does not reach them, and stand the cut ends in the hot water for thirty seconds. Then move them straight into deep cool water for an hour.

The mechanism is simple: heat expands the air trapped in the blockage and forces it out of the cut, and the stem starts drawing water again as it cools. You will often see the difference within twenty minutes.

Do not use this on soft or hollow stems. Tulips, anemones, ranunculus, sweet pea and daffodils will cook. For those, the deep cool water soak above is the whole treatment.

The paper wrap, for roses with bent necks

A rose that has folded just below the head is the classic case, and the wrap is what florists actually do.

1. Re-cut three centimetres off the stem, at a slant, under running water.
2. Lay the roses together on a sheet of newspaper or florists' paper, heads level.
3. Roll the paper firmly around the whole bunch, from the stems right up past the heads, so the necks are physically supported straight. Firm, not crushing.
4. Stand the wrapped bundle in deep cool water for two to three hours, or overnight if you can.

The stem rehydrates while the paper holds the neck in the position you want it to set in. Unwrap, and a good proportion of them will have straightened. It does not work on every rose, and it does nothing for a rose that has simply reached its end, but on a fresh bunch that wilted early it is close to a reset.

Hydrangeas have their own version. The whole flower head takes up water through its surface, so a wilted hydrangea can be submerged head and all in cool water for half an hour, then re-cut and returned to the vase.

Fixing a bacterial vase

Do all of it, or none of it. Half measures leave the colony in place.

Take every stem out. Scrub the vase in hot soapy water and rinse it twice. Rinse the slime off the lower stems under the tap with your fingers. Cut three to four centimetres off each stem so you are above the discoloured section, and check the cut end: it should be pale and firm right through. A stem that is brown in the middle above your cut has gone, so take it out of the bunch entirely. Refill with fresh cool water and a full dose of food, and change it daily for the next few days rather than every second day.

When nothing will work, and that is fine

It is worth saying plainly, because most flower care writing will not. Some flowers are finished, and there is no technique that reverses it.

You are past the point when the petals go translucent, when a stem is soft rather than firm, when a lily's petals lose their waxiness, or when the flower has shed its pollen. Those are signs of a flower that has completed what it was doing. Sweet pea at day five and tulips at day seven are not failures, they are the normal ceiling for those flowers.

There is usually something left worth having. Pull the survivors out, re-cut them and put them in a smaller vase; a mixed bunch will often leave you three or four carnations and some alstroemeria that will run another week. Roses, hydrangeas and gypsophila that are past their best in water are exactly the ones worth drying instead, and hydrangea heads in particular are better dried slightly late than early.

Then start the next bunch properly, because most of vase life is decided in the first ten minutes.