How does boiling water revive cut flowers?

How does boiling water revive cut flowers?

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A classic tip to revive wilted cut flowers is to plunge the stem into boiling water for some period of time, and then back into cold water.

What process is occurring that causes the flower to be "revived"?

I could not find any scientific papers that have done research into this phenomenon but the general reason given for wilted flowers to being resuscitated is given as the hot water being absorbed faster and I quote

Florists use warm water only for resuscitating wilted flowers, because warm water is absorbed quickly. For restoring wilted stems, hot water (110 degrees Fahrenheit) is recommended. For woody or badly wilted stems, very hot water (180 to 200 degrees) is better. Florists then move them into a refrigerator (reference).

The reason for absorbtion faster is given as

luke warm water in a vase arrangement because warm water is “thinner” (has fewer air bubbles) and moves up the stem faster than cold water (reference) and Warm water molecules move faster than cold water molecules and so can be absorbed by flowers with greater ease (reference).

Conditioning Cut Flowers and Foliage

Many people enjoy cutting plants from their garden to use in bouquets and floral arrangements. To get the most out of your cut plant material and make it last for the longest possible time, condition it properly using a few tried and true techniques.

Conditioning plant material simply means making sure it is as full of water as possible. Conditioning methods vary with different plants types. The guidelines that follow will help you get the most out of your plants.

Cutting: Choose flowers that are not quite fully developed as they will continue to mature after they are cut. When to cut sometimes depends on the season or time of day. Generally speaking, cut when plants are already as full of water as possible. For many southern gardeners, especially in the summer, this means in early morning when dew still dampens the leaves. For others it means late afternoon or early evening after the plants have spent the day making food. Always water plants well a few hours before cutting to increase turgidity.

We have all seen pictures of people with fancy baskets in the garden cutting flowers and laying them in the basket. A better idea, for the flowers, at least, is to take a bucket of water into the garden when cutting flowers. Place the cut stem immediately in water. A stem out of water forms an air lock that prevents the uptake of water and significantly shortens its life.

Cut each stem at an angle with a sharp implement and remove any leaves that will be under water. Recut the stems under water at a sharp angle to expose more surface area. Cutting under water prevents the formation of an air bubble that inhibits the uptake of water. Place the newly cut stems in tepid water and let them stay for two or three hours or overnight.

Generally speaking, the conditioning bucket should be about a quarter full of warm water to which a floral preservative has been added. Warm water is taken up by the stem more quickly than cold water. Throughout the process, all tools, including the conditioning bucket, should be kept clean and as free of bacteria as possible.

Floral preservative extends the life of most cut flowers by giving them a source of food and inhibiting the growth of bacteria. While commercial products work well, it is easy to make your own. Simply add a tablespoon of vinegar, a teaspoon of sugar, and three to five drops of household bleach to a quart of water.

What are some conditioning techniques for different types of plants?

Woody stems, such as azalea, rose, pittosporum, lilac, viburnum, eucalyptus, and podocarpus, should be cut at a sharp angle and then split up from the bottom about half an inch. Never hammer or crush the stem as this damages the stem tissue and inhibits uptake of water.

Semi-woody stems such as chrysanthemum, lily, zinnia, and ferns, should be cut at a sharp angle and lower foliage that would be under water removed immediately. Leaves left under water begin to deteriorate quickly and cause a buildup of bacteria that can clog the cut stem. Furthermore, they will make the water cloudy and fetid if left for an extended time.

Soft stems of gerbera, freesia, and tulip should be conditioned with water up to their necks. They will be ready for arranging after an overnight drink.

Hollow stems on such flowers as amaryllis, delphinium, and lupine should be cut at an angle, turned upside down, and filled with tepid water. Plug the stem with cotton wool to hold the water inside the stem before placing it in the conditioning bucket. To keep the end of the stem from curling, put a rubber band around it or encircle it three or four times with floral tape.

Plants that exude a milky substance when cut, such as poppy, euphorbia, and poinsettia require special treatment. Stems of these plants should be burnt in a flame to seal the stem before conditioning. This milky sap can cloud the water and clog stems of other flowers in your design. In addition, it may irritate your skin. This sealing process should be done each time a stem is cut. The nature of this type of stem makes it unsuitable for use with sharp needlepoints or needle type holders.

Caladium: Cut stems as long as possible and place in water. Stems will wilt for the first day, but they will perk up thereafter. Do not refrigerate. Leaves will last for about two weeks, but the color will fade as time progresses.

Hydrangea: Cut when flowers are fully mature and turning a bit papery as very young flowers do not condition well. Hydrangea benefits from a boiling water treatment. Pour boiling water in a jar and place the stem ends in the boiling water for a minute or so. Remove the stems, recut, and place them in the conditioning bucket up to their necks or immerse them completely overnight. If blooms still wilt, dip the end in alum powder and return to the conditioning water.

Foliage: Single leaves, palm fronds, or branches of foliage with thick substance and a waxy surface such as camellia, and evergreen branches such as juniper can be completely immersed in water for conditioning. However, gray or wooly foliage should never be immersed as the leaves absorb water and spoil the color. Very new growth should be avoided as it does not condition well.

Carnations: Cut between nodes or joints. Water will not be taken up if cut on the joint.

Tulips and gerberas: Wrap in newspaper for conditioning. Flowers continue to grow when cut and will become crooked if not forced to keep straight. They also turn toward a light source. This tendency has spoiled many a perfect design, so take this into consideration when choosing tulips and gerberas for a design.

Lilies: Remove stamens to prevent pollen from staining clothing, flower petals, and tablecloths.

Bulbous stems: Most flowers of these plants, like daffodils, tulips, and hyacinths are pulled from the plant instead of cut. This method of pulling yields a stem that is white and firm and does not allow the optimum uptake of water. Cut off the white part of the stem before placing in warm or cool water. Warm water will make the flowers open more quickly.

When all else fails: If flowers wilt even after conditioning, recut their stems and place in boiling or near-boiling water for a minute or so to destroy the airlock that prevented the uptake of water. Wrap the flowerheads in paper to protect them from the hot water. After the flowers revive, recut the stem and place them in your arrangement.

Why Do Cut Hydrangeas Wilt So Fast?

Hydrangeas are usually some of the first flowers to start looking sad in an arrangement because they have thick, woody stems that produce a sticky sap, which can make it tricky for them to take in enough moisture in a vase to reach the entire flower. But hydrangeas are also one of the few plants that can draw moisture in through their florets, so it&aposs possible to perk up wilted blooms by completely submerging them in water and letting them sit for a few hours to rehydrate.

This trick for reviving cut hydrangeas may not work every time, but it’s worth a shot if you have a few stems you’re not quite ready to toss yet. According to Rizaniño Reyes, a floral designer based in Seattle, the success of this hack depends on a few factors, including “when the flowers were cut and how long they&aposve been in a box in cold storage post-harvest.” You&aposll probably have better luck reviving slightly wilted fresh-cut hydrangeas, while ones that have been in storage longer might be a lost cause (but still worth a try!). “I&aposve done this with reasonable success, but it&aposs never 100% from my experience,” Reyes says.

Don&apost be tempted to try this with other common cut flowers like roses, peonies, or tulips to bring them back from the brink of wilting. They don&apost have the ability to draw in moisture through the blooms like hydrangeas, so soaking them will only make them rot and wilt faster.

In my reading and research about post-harvest care for flowers, I came across something called the "Boiling Water Method" for reviving wilted stems.

I was truly skeptical because the idea of placing stems in boiling water seems insane. In my experiments, I was attempting the opposite - re-cutting the stems and placing them into cold water. It didn't work.

I decided to give the "Boiling Water Method" a shot on some stems that I was about to throw out. I had cut the stems early in the morning, but they still wilted immediately. and a day later, even after being stored in my floral cooler overnight, they still looked terrible.

Time to try the "Boiling Water Method". This is what I did:

1. Boiled water on the stove and poured it into a jar.

2. Re-cut the stems at an angle with clean, sharp flower clippers.

3. Immediately plunged the stem end into the boiling water, angling the blooms out the jar to avoid "steaming" the blooms.

4. Set a timer for 1 hour and walked away (I wanted to watch, but I had work to do!)

*NOTE: This was my first attempt. I learned that it's probably best to fill the jar with about 1 inch of water, so only a small part of the stem is "cooked". That part of the stem can be cut off later.

Also, one hour is probably unnecessary - I was headed out to work and wasn't able to check back earlier.

If you are concerned about "cooking" the stems, try dipping for 10 seconds for soft stemmed flowers and up to a few minutes for "woody" stemmed flowers like hydrangeas. After "searing" in the boiling water, place the stems in cool water.

When I returned, the water was cool and this is what the stems looked like:

AMAZING. I was in shock. 2 minutes of work and these flowers were back in business!

I removed the stems from the jar and added them to an arrangement in my dining room. 6 days later, the stems were still looking GREAT.

Now obviously, if your blooms are 5-7 days old and they start wilting, you need to simply accept that they are dying a natural death. Flowers don't last forever.

However, if your blooms are freshly cut and wilting, then you can certainly give the "Boiling Water Method" a try. What do you have to lose? It's better than your other option - throwing them out.

Some Great Tips to Keep Your Flowers Looking Lovely Longer!

  • If you have guests coming for lunch, put your flowers in the closet for about an hour or so. Bringing them out and exposing them to the light of day (right before your guests arrive) should perk them right up.
    (Only works in the daytime).
  • When your gorgeous bouquet of flowers begins to wilt, grab a can of hairspray and hold it about 18 inches away from the underside of the leaves and petals, spraying hairspray upward. Commercial hairsprays contain glycerin and a class of acrylic resins which will help them survive another few days.
  • Now for wilting flowers that you want desperately to revive, dissolve an adult aspirin in half a cup of warm water, and pour it into your vase. And, before you throw them out completely, cut the stems again on a slant and put them in fresh, warm water.
  • If you happen to have a bouquet of short-stemmed flowers, put them in a container with sand saturated with warm water. They should look great and last a while.

Read my tips for keeping your daffodils looking beautiful longer!

Care of Cut Flowers and Foliage

Floral designers want the cut flowers in their arrangements to stay in good shape as long as possible. However, we first need to understand why flowers die in order to keep them fresh.


The stage at which to cut flowers. Each type of flower has a proper stage of development or maturity for cutting, which for most flowers is just before they are fully open or mature. That is, the blooms are more developed than tight buds but not so old that they are starting to deteriorate. Examples in this category include baby’s breath, chrysanthemum, carnation, pinks, cornflower, cosmos, dahlia, delphinium, geranium, nasturtium, sunflower, and snapdragon.
Some flowers keep best when cut in the bud stage or when just starting to open, for example, daffodil, iris, peony, poppy, and tulip. Gladiolus may be cut when the two lowest buds are open or can be allowed to develop more fully. Some flowers keep best when fully open at cutting time examples are a daisy, marigold, orchid, violet, and zinnia.

The above suggestions apply to flowers that are cut in the garden. When brought from a florist, the flowers are usually somewhat more open. Note that the cutting and handling of roses requires special care and is discussed separately and in detail in a later section. The best time of day. Late afternoon or evening is the best time since the plant has more stored food then. Early morning is the next best because the plant is turgid then. Avoid cutting flowers in the heat of the day when the plants are wilted.

How to cut the blooms.

Cut the stems somewhat longer than needed, using a sharp knife or shears. The additional stem length is necessary for later re-cutting when the flower is placed in water or into an arrangement. As each stem is cut, remove all the leaves that will be in the water. Also, be especially careful to remove any leaves that are diseased, insect-damaged, or insect-ridden. In addition, take off damaged or diseased petals. As each stem is cut and the unneeded leaves are removed, the stem should be placed immediately into a pail of warm water. This is especially important if a large number of flowers are to be cut or if it is a hot day. To further prevent wilting, cover the flowers in the pail with a plastic bag.

Conditioning flowers after cutting.

Regardless of how careful you have been in cutting flowers in the garden, a certain amount of wilting will occur. It is necessary therefore to condition the flowers so that they are again full of water before they are arranged. Conditioning should last at least one and preferably several hours. Overnight conditioning is even better. For flowers brought in from the garden or purchased from the florist, do the following:
1. Have the containers of warm water ready (about 100o – 110o F., bath water temperature). Although warm water is better than cold, many flowers are not “fussy” and take up cold water readily. In case of doubt, use warm water.
2. The water should be about half the depth of the entire stem length, preferably containing a floral preservative or bacteriacide.
3. Recut the stems at an angle. Remove one to two inches with a sharp knife (or shears), under warm water, if possible. Probably the easiest way to do
this is to make the cut while holding the stem under running warm water. Then immediately place the stem into a container of warm water with preservative before the stem end dries.
4. When the stem is handled for re-cutting, remove any leaves that will be in the water.
5. Keep the blooms dry and out of the water.
6. Store the containers of cut flowers in a cool, humid place, free from drafts.


Water quality affects flower life. Both hard water (containing many dissolved materials) or hard water that has been “softened” with a home water-softener are unsatisfactory for keeping flowers fresh. Hard waters are often alkaline (pH 7 to 10) rather than acid (pH 4 to 6). The only satisfactory means of improving hard or softened waters is to distill or deionize them, or you can buy water that has been so treated. Rainwater that is relatively clean is also useful. Floral preservatives contain some acidifying material that helps make water more acid and desirable. However, hard alkaline waters may require twice the amount of preservative as distilled, acid or naturally soft water.


Prevent wilting and improve water uptake. Extending from the roots through the stem and out into every part of the leaves and flowers are water-conducting xylem cells through which water moves to keep the whole plant turgid. This lifeline of xylem cells must continue to work to prevent wilting and death. For water to continue to circulate, some must be transpired (given off and lost) by the leaves and flowers. If transpiration is too rapid, the plant wilts and dies. Thus, to keep the flowers, leaves, and stem from wilting, water must be continuously taken up into all parts of the plant but must not be lost too rapidly. Enhance water uptake. Since most of the water comes in through the cut end of the stem, this surface must be kept functioning. The following steps encourage water uptake.

1. Cutting stems under warm water and immediately placing them into a container of warm water prevents air bubbles from getting into the cut end of the stem, plugging up the conducting cells, and preventing or slowing down water uptake. Warm water forces out any bubbles that by chance get into the end of the stem.

2. Bacteria attach and destroy the cut end of the stem and effectively plug up the conducting tissues. This condition is the most frequent cause for short flower life. All plant tissues in water will rot, but leaves do so more readily. Use a bacteriacide (such as chlorine bleach) or a floral preservative to control bacteria.

3. A sharp knife used to make a clean diagonal cut does minimal damage to the stem end. The only practical way to cut a flower stem with a knife is diagonal. The sharp stem end also penetrates floral foam more easily when the flowers are arranged. Sharp shears can be substituted when a knife is difficult to use, but avoid crushing the stems.

4. Use care not to bruise, cut, or damage the bark or stem surface, or to break
the stem when handling flowers.

5. Check the water level in the container daily, and add enough to keep all stems in water. This is especially important if floral foams are used as stem holders.

6. If the water becomes cloudy, change it. Wash the container thoroughly, and recut the stems to get rid of bacteria and to expose a fresh stem end.

7. Use only clean, thoroughly washed or sterilized vases and containers.

Prevent water loss and wilting.

Once the leaves and stems are full of water, excessive water loss can be minimized as follows:

1. Store flowers and finished arrangements not on display in a cold, humid place out of the sun and away from other heat sources or drafts. A refrigerator set at 40 to 50o F. is satisfactory. Always wait to arrange your flowers until they are full of water. A plastic bag or sheet placed over the blossoms will raise the humidity and prevent drafts, either in or out of the refrigerator.

2. Keep the flower stems in the container of water until they are to be arranged. Flowers out of the water will soon dry out and wilt. Avoid unnecessary handling. Remember that your hands are warm and will dry out the flowers.

Use the stem as the flower’s ‘handle.’ Treat woody stems. Branches of flowering or leafy shrubs or tree branches (i.e. forsythia, privet, spirea, pear, and redbud) and some plants with woody stems (i.e. chrysanthemum) sometimes require special treatment:

1. Prune the branch to remove all excess leaves and flowers, and remove any that will be in the water.

2. Split the cut end one to four inches with a strong knife or shears. Split the larger branches into several planes. Then cut them an inch or so from the base under warm water and place the stems in warm water containing a preservative. Allow them to soak for several hours but preferably overnight.

3. If possible, cut the branch so it ends in the softer, new growth where the bark and wood are not so thick and hard.

4. Cut more branches than you expect to use, for even with the best of care, not all will take up water satisfactorily.

Treat stems that bleed milky sap. Poppies, poinsettias, euphorbia, and some dahlias have difficulty in absorbing water after being cut. Place the stems in hot water or dip the lower ends in boiling water for 5 seconds. Another method is to sear the cut ends with a flame for a few seconds and then to place the stems in warm water. Conserve food stored in flowers, leaves, and stems. A cut flower will die, even though it is full of water when its supply of food is used up. The best stage of development for cutting each kind of flower is related to the amount of stored food in it. Young, immature flowers have not accumulated much food, while old flowers that are past their prime have almost exhausted their reserves. If the flower has been cut at the proper stage, the food supply can be conserved or supplemented in the following ways:

Store flowers in the coldest place available that is above freezing. Most flowers keep longest at 35 o F. Temperatures of 40 o to 50 o F. are most likely to be available and are satisfactory except for long-term storage. A few flowers, such as gladioli, keep best at 50 o F. As mentioned earlier, finished flower arrangements will stay fresher longer if kept in cold storage when not on display. When displayed, the arrangements should be placed in a relatively cool area if possible. Avoid radiators, sunny windows, the tops of television sets, and other such places.

Use floral preservatives. A number of commercial floral preservatives are available, and, if used properly, can prolong the useful life of cut flowers by one to several days. Sometimes
the lifespan is even doubled. Carefully follow the directions for these brand-name products.
If you know that your water is quite alkaline (pH 8-10) or hard, or both, use up to twice the
recommended amount. You may also wish to experiment on your own.

Several homemade floral preservatives such as the following work quite well:

1. 2 teaspoonfuls (t.) sugar + 1/2 t. chlorox ) or similar material) + 1/4 t. alum + 1 quart water.

2. 2 tablespoonfuls (T.) white vinegar + 2 t. sugar = 1/2 t. chlorox + 1-quart water.

3. 1 pint non-diet (must contain sugar) non-cola drink (i.e. Sprite, 7-up, etc.) + 1/2 t. chlorox + 1 pint water.

All floral preservatives prolog flower life best if used when the blooms are first cut from the garden. Cut the stems under warm water and place them immediately into warm water containing the preservative. Preservatives are worth using even later, for example, after the flowers are received from a florist. If it usually necessary to change the water, but if it does become cloudy (indicating unusual bacterial activity), the solution should be changed. In addition, wash the stem ends and container and also recut the stems.

Most floral preservatives, including homemade ones, contain ingredients that do the following things:

(1) provide sugar to supply energy for the flower as its food supply is exhausted

(2) contain a bacteriacide ton control the bacteria that decay the stem and prevent water uptake and

(3) supply an acidifier that will increase acidity to a pH of 4.5. This pH level slows down bacterial activity and approximates the acidity of plant sap, which encourages better water uptake.

Many commercial preservatives also contain ingredients that, according to the manufacturers, may help retain flower color, increase water uptake, and reduce the rate of food usage.
Repeated scientific testing has shown that aspirin or pennies (to supply copper to reduce bacterial activity) in the water do not prolong the useful life of cut flowers.

Prevent injury from ethylene gas. Ethylene gas will cause many flowers to close up or wilt rapidly and die. The very small amounts of ethylene that will cause flowers to die cannot be detected by smell. Certain plants are especially sensitive to this gas and are sometimes used to detect its presence. For example, the leaves of tomato or marigold plants will turn down, and snapdragon florets fall off when exposed to minute amounts of ethylene.
Ethylene gas is given off by most fruits and vegetables, especially apples. As these fruits and vegetable decay, even more, gas is produced. However, decaying and diseased flowers, leaves, and stems also give off ethylene. Do not store your flowers with fruits, vegetables, or decaying plant materials.


The rose is the favorite flower of many people. Roses, however, sometimes do not keep well, possibly because they are cut too “tight,” allowed to open too much, or because they somehow fail to take up water. The proper stage of development is all-important when cutting roses from the garden. The best time is late in the afternoon when the rose is full of water and has the most stored food.

When to cut a rose. The proper stage of development depends on the number of petals. Rose varieties with 30 to 40 petals have graceful, urn-shaped buds. Cut them when one or two outer petals have loosened from the bud and the green sepals have turned down. Some roses have many petals (60 to 90) and short, fat, rounded buds delay cutting them until three or four petals have separated from the bud. If cut too tight, they may never open. Roses with
few petals (20 or less) and long, slender buds should be cut “tight,” or just as the tips of the petals show color. If cut when they are open, these roses will open fully very rapidly.
After cutting, remove leaves that will be in the water and remove the prickles carefully so as not to injure the stem’s bark. Then recut the stem under warm water and place it immediately into a container of warm water with preservative.

How to buy long-lasting roses. Good florists can be trusted to supply fresh roses at the right stage of development. Roses should have been in the water with a floral preservative long enough to be conditioned and firm so that they will open fully and remain attractive for several days. The outer one or two petals should be loose, with the sepals turned down around the stem. The flowers should have a rich, fresh color and a crisp feel. Look for the
following signs to recognize “poor buys.”
Old roses: many petals loosened little bud left in the center a dull, faded look a soft, flabby feel and water-soaked foliage. These roses will open rapidly and be shortlived, so avoid buying them.
Immature roses: no petals loosened, and definitely cut too tight (if the bud is short and fat, it may never open) the bud feels hard, and the sepals are tight against the bud. Special care is required to get immature roses to open properly, so don’t take a chance in buying them.

How to care for gift roses. You may receive roses as a gift, packed in a box without water, or arranged with their stems in a container of water or in wet floral foam. Here are some tips to get the most enjoyment from them.

Boxed roses without water.
• Remove all foliage that will be in the water.
• Cut the stems up about one inch from the ends while holding them under warm water.
• Place the cut stem ends in warm water containing a floral preservative. Keep the roses in a cold, draft-free place while they soak up water.
• When arranging them, recut the stems and immediately place the roses in a container of warm water with a preservative. Soak floral foams in a preservative before use.

Roses arranged in a water-filled container.
• Check the water level in the container fill it to the brim with water or a preservative solution.
• Check the water level daily.
• Place the arrangement in the coolest place available for display refrigerate it when not on display. Avoid drafts, direct sun, or heat.

Reviving wilted roses.

If a rose wilts or is wilted upon receipt, try doing the following:
Remove it from the arrangement recut the stem under water as above submerge the entire rose, including stem and foliage, by laying it out flat in a pan of warm water or in the bathtub and replace it in the arrangement after it has revived by becoming full of water again (often after 20 minutes to an hour). Some immature roses, which have been cut too tight and have wilted severely at the “neck” (the stem just below the flower), can never be revived.

One way to fight food waste: Revive wilted produce

A typical Wednesday night at my house goes something like this: Open refrigerator, take lettuce and other vegetables out of crisper, see that most of them are wilted, return them to refrigerator. Realize meat isn’t defrosted, whip out iPhone, order Thai food delivery.

That typical Wednesday night is followed by my Saturday morning routine: Go to the farmers market, buy great stuff, come home, open refrigerator, slide out crisper drawer, throw (almost) everything away from week or two before, replace with new stuff. Lather, rinse, repeat.

By my back-of-the-envelope calculations, I’ve thrown away just over $1,200 in produce so far this year. I’m not proud of that.

In fact, I’m pretty embarrassed. When I buy meat, I use every bit of it, including the bones for stock. Why am I so careless with produce?

I’ve made a real effort to break this bad habit. I try to eat vegetables with every meal. Still, Swiss chard and romaine lettuce leaves droop and sag after a few days at home, and there are only so many stir-fries and soups one can make when carrots, green beans and asparagus get bendy. Sometimes you just crave something fresh and crunchy without wanting to drive to the grocery store or wait a few days for the next farmers market to open.

I wish I had the time and lifestyle to shop for food every day. But even if I did, a one-person household takes longer than a family of four to go through a head of lettuce or a bunch of carrots. Even when I’m trying, vegetables often wilt before I can manage to get to them.

With a firm resolve to save money and be respectful of the farmers who grow the produce I eat, I’ve been on a mission to extend the “fridge life” of my vegetable staples. So I turned to the experts to learn more about how to revive what I’ve got and better store what I buy.

That’s what Bernard Boyle of Garner’s Produce tells me at the 14th and U Farmers Market on a sunny Saturday morning. He’s right. We all learned in high school biology that the human body is about 60 percent water. What I’ve discovered in my let’s-try-not-to-be-so-wasteful vegetable research is that plant foods have us beat: Most fresh vegetables in the typical American diet are more than 90 percent water by weight, according to Nathan Myhrvold and the team that wrote the epic food science and technology tome “Modernist Cuisine: The Art and Science of Cooking” (The Cooking Lab, 2011).

For example, they found that a carrot is roughly 88 percent water, nearly the same proportion found in milk. A fresh cucumber contains a higher proportion of water than some mineral-rich spring waters. Swiss chard is 94 percent water.

In “Keys to Good Cooking: A Guide to Making the Best of Foods and Recipes” (Hodder and Stoughton, 2010), food science expert Harold McGee writes that fresh vegetables and herbs gradually deteriorate as they use up their limited water reserves after harvesting. That makes sense. But can you give them a little boost before they cross over to the rotten side, and if so, how?

Consumer advice about reviving vegetables runs the gamut: room-temperature water vs. ice water submerging the whole vegetable or soaking just the ends adding salt, sugar or vinegar to the water. Chefs, food companies, scientists and food bloggers offer a variety of methods juggling time, temperature and those additives, with the one commonality being water.

Kathleen M. Brown, professor of plant stress biology at Penn State University, teaches a post-harvest physiology class and has researched this topic. Her advice: All you need is water.

“Additives actually reduce the difference in osmotic potential between the vegetable and water and reduce the rehydration rate,” she says. “Besides, you don’t need those flavors.”

Air and water temperature matter during the revival process, Brown advises. “When the air temperature is lower, the vapor pressure deficit — the driver of moisture loss — is smaller.” She tells me I should soak vegetables in cold water from the tap to revive them, and do so in the refrigerator instead of in my warm kitchen.

For vegetables that have a heavy cuticle, or waxy exterior layer that might not admit water as quickly — Swiss chard and celery are examples — Brown suggests trimming the stems and putting them in a glass or vase of water, as you would fresh-cut flowers.

How do you know when they’re refreshed? “When the vegetables are well hydrated, there is a higher pressure in the cells, and they break and release moisture more easily when you chew, so they seem crisp,” says Brown.

Can vegetables be over-hydrated? Sort of. Gardener and chef Deborah Madison, whose latest book is “Vegetable Literacy” (Ten Speed Press), cautions that when you wash or revive leafy greens such as lettuce, kale or chard, you need to dry them thoroughly if you’re not going to use them right away: Water remaining on the outside invites bacteria. In fact, she breaks apart her lettuce and other leafy greens, rinses and dries them, then stores them in a plastic bag with a clean, dry dish towel or paper towels to absorb any remaining moisture on the leaves.

But then what? After we get all that water back in vegetables, the refrigerators we put them into take it out all over again.

“In basic refrigeration, the cooling system is in the freezer, and the refrigerator gets its cold air from the freezer,” says Michael Mattingly, senior refrigeration product manager at GE. “The colder you make your freezer air, the more humidity is stripped out.”

Mattingly explains that humidity in refrigerators comes from two sources: outside air flowing in when you open the refrigerator door and humidity given off from fruits and vegetables inside. New, high-end refrigerators have dual-evaporation systems: separate cooling systems for the freezer and the refrigerator, allowing for better humidity control. And most residential refrigerators also have some level of adjustable humidity control in the crisper drawers that the owner’s manual or product Web site should give guidance on how best to use. Just know that although adjusting the drawers’ humidity can help with storage, it won’t stop the vegetables’ natural process of losing moisture.

The challenge for many consumers, myself included, is that crisper drawers are at the bottom of the refrigerator. Though Mattingly explains the engineering and aesthetic design rationale behind that placement, and it makes perfect sense, out of sight is out of mind.

Madison keeps flours, grains, nuts and dried fruit in her refrigerator crisper drawers — not vegetables.

“I store vegetables in plastic bags on the shelves in my fridge, and it works just fine,” she says. Keeping them in plastic bags provided by vendors gives vegetables a better chance at lasting longer.

It’s common sense that the foods kept at eye level are the ones you will use most in your cooking, says Madison. If you’ve lost sight of vegetables and they have wilted, it’s worth trying to rehydrate them. But if they’re past the point of no return — if your produce has changed color, is covered in dark spots or has discolored, liquefied, become slimy or generated obvious bacterial or mold growth — discard them.

Better yet, “compost them!” says Madison. “Returning them to the earth should make you feel less guilty.”

Top tips on how to make cut Hydrangeas last longer

More Tips to Make Hydrangeas last when cut from the garden.

  • Before cutting your Hydrangea bring a bucket of water into the garden with you.
  • Cut the stem on the Hydrangea bloom as long as possible, immediately place the stem into your bucket of water and cut the Hydrangea to you desired length in the water and on a 45 degree angle. This will allow the hydrangea to drink more water.
  • When you bring your cut Hydrangea blooms indoors, boil up some water and fill your vase/ bucket.
  • Cut about 5cm from your hydrangea stem and immediately place the stem in the boiling water and leave them there.

I know it sounds mad, but leave them there and you will be amazed how they perk back up.

If you do not have flower food available and you are sure you vase or containers are spotless, you could use a table spoon of sugar.

Caution: If your vase has not been thoroughly cleaned (bleached) the sugar will feed any existing bacteria in the vase and cause it to multiply rapidly.

Hydrangea, do prefer for the bloom to be kept in a cooler environment and away from drafts or direct sunlight. Hydrangea also drink water from their bloom heads so using a mister gun spray the blooms with prolong the life of the Hydrangea and if you find it is wilting quickly dunk its whole head in room temperature water. (NOT BOILING)

The Boiling water treatment can also be used to revive wilting heads after a day or so and the Hydrangea heads can look as fresh as the day they were cut from your garden.

This boiling water trick also works really well for treating roses cut from the garden or roses that may have been left out of water for more than an hour but ONLY place in water for 25 seconds and place into cold water.

In a Commercial Environment you will probably have access to Floralife Quick Dip which is an amazing professional product that replaces the Boiling Water Treatment. Make sure to follow the intructions very carefully when using Floralife Quick Dip

Helpful Hints to Make Cut Flowers Last Longer

CUT flowers will last longer if they are gath ered properly, and conditioned in deep warm water before they are arranged. The best time to cut them is in the evening. If this is not convenient, cut them in the early morning when the dew is gone but before the sun has robbed them of some of their mois ture.

Flowers wilt when they transpire more moisture than they absorb and this factor varies in different species. The tendency to wilt is great est during the first few mi nutes after cutting when the plant is in “shock.” For this reason, cut flowers should be placed in water as soon as they are cut.

The U. S. Department of Agriculture recommends wa ter at a temperature of 100 to 110 degrees (lukewarm). It is taken up more rapidly than cold water and in greater quantity. Use of a chemical preservative helps. Accord ing to the U.S.D.A., “The use of chemical preservatives in the water is highly recom mended to increase storage or vase life. This is true at all stages of distribution: grower, wholesaler, retail florist and consumer. The vase life and general keeping qualities are markedly im proved, often doubled, by the use of preservatives.”

Preservatives are available from florists and some hard ware stores. Most of them contain ‘sugar, a bactericide (often a chlorine compound), an acidic substance to reduce the pH of the water. Some contain metallic salts and senescence or resiratory in hibitors. Sugar alone may do more harm than good be cause it allows increased growth of micro‐organisms which clog the stems. Aspirin, pennies, and salt are worth less.

When cutting garden flow ers take to the garden a pail containing several inches of water or preservative solu tion, and place the flowers in it as they are cut. Cut the stems slantwise, preferably with a sharp knife. Scissors tend to pinch the stems and the tiny water‐conducting tubes inside them.

A slantwise cut is ad vocated for several reasons. More surface is exposed to water, stems that require splitting are easier to handle, and the end of the stem can not come to rest in a flat position on the bottom of the container.

When the flowers are gath ered, take them inside im mediately. Fill the pail with warm water up to—but not touching—the blooms and leave it in a cool dark place, free of drafts, for several hours or overnight. As far as water intake is concerned, the depth of the water is not important because most of the water enters through the cut stem. However, deep water reduces transpiration from the leaves and humidi fies the surrounding air.

Some flowers require spe cial treatment. Those with a sticky sap—poppy, poinsettia —wilt quickly unless heat is applied to the end's of their stems. Sear the ends quickly in a flame or dip them in boiling water for several sec onds. A cornucopia of paper can be used to protect the flowers and foliage from steam. After either treatment, place the flowers in warm water for conditioning. Heat discourages the flow of sap which otherwise hardens and prevents the uptake of water.

Dahlias, which tend to wilt easily, will last a week or longer if treated properly. Place them immediately in the container which is to hold them and cut off a small portion of the stems urider water. Or scrape the bottom three or four inches of the stems before placing them in water. Another suggestion is to apply heat to the stem ends, as described for flow ers with a sticky sap.

Flowers with woody stems —chrysanthemums, lantana, stock—will absorb more mois ture and last longer if their stems are split. Split the ends of short sprays one or two inches, long sprays three or four inches. Crushing the stem ends with a hammer, dong recommended, releases bits of plant tissue into the water. These decay and pro mote the growth of bacteria which soon clog the stems.

Cut flowers that have started to wilt Prematurely can be revived by the follow ing treatment Make a slant ing cut an inch or so from the end of the stem and place the stem in very hot water for several minutes. Boiling water removed from the stove for several minutes is recommended. Afterward, plunge the stems into cold water. The hot water drives out any air bubbles that may have formed in the stems and permits the cold water to rise and revive the flowers. This treatment will not revive flowers that have reached their prime or flowers that have been wilted for several hours.

Flowers from the florist have already been condi tioned but may have lost moisture in transit. Play safe. Recut the stems, remove damaged petals and leaves, and recondition them in deep warm water for two or three hours. Blackened stem ends and a dry appearance in dicate that such conditioning is badly needed.

Vases and containers for flowers should be kept scru pulously clean. Wash them frequently with hot water and a detergent containing a disinfectant. When arrang ing flowers, handle them as little as possible and lift them by their stems. Remove leaves that will be sub merged unless they are need ed in the design because they soon decay and cause wilt ing. Recut the stems daily and change the water in the container if plain water is used. If a preservative is used, this is not necessary.

Keeping Cut Flowers Fresh

Be careful when dealing with anything glass. Take caution if glass breaks not to cut yourself.

Approximate Time Required to Complete the Project


Do cut flowers last longer in warm or in cold water?

Project Goals
  • Put the two carnations in warm water with blue food coloring to see how fast the plant absorbs the water.
  • Put two carnations in cold water with red food coloring to see how fast the plant absorbs the water.
  • Is warm or cold water best for cut flowers?

Materials and Equipment

  • 6 Carnations
  • 2 vases/jars/glass bottles
  • Red and blue food coloring (or any two colors of your choice)
  • Pencil and paper
  • Camera (optional)
Where can the materials be found?

The carnations can be purchased at a florist or grocery store. The food coloring is found at a grocery store as well.


Cut flowers are beautiful when new. What is the best way to keep them looking fresh? Will they last longer in warm water, or will they keep longer in cold water? With white carnations and food coloring we should be able to find out the best way to keep our cuts flowers looking their best!

Research Questions
  • Will warm water allow cut flowers to last longer?
  • Is cold water the best way to keep cut flowers longer?

Terms, Concepts and Questions to Start Background Research

You will watch the food coloring travel to the petals of the plant. Which color will travel faster, the color in the warm water or the color in the cold water?

Experimental Procedure

  1. Gather your supplies.
  2. Take three cut carnations and place them in a vase of cold water.
  3. Take another three carnations and place them in a vase of warm water.
  4. At the same time add blue food coloring to the warm water and red food coloring to the cold water. Label the vases warm and cold so you know color to add to which vase.
  5. Observe the white carnations. Which one absorbs the water with the food coloring first? This will determine which temperature is drinking the water faster.
  6. Take notes as you watch the progress.
  7. Take pictures as well.


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