Twelve myths and truths about flowers

The flower trade is full of inherited advice that nobody ever checked. Here are twelve, with a verdict.

1. Aspirin makes flowers last longer — myth

The idea is to acidify the water, which does help. The problem is the dose: the amount of aspirin needed to shift the pH of a liter (about a quart) is far greater than the one tablet that gets dropped in.

2. A copper coin disinfects the water — myth

Copper is a fungicide, but a modern Argentine coin has almost no copper in it and releases practically nothing into the water.

3. The little packet of flower food works — true

It combines sugar (energy), an acidifier (better water uptake) and a biocide (slows bacteria). It is the only one of the three formulated to do what it claims.

4. Fruit next to the vase shortens the life of the bouquet — true

Ripe fruit releases ethylene, the plant hormone of aging. A fruit bowl next to a vase can take half the days off a bouquet. It is one of the most underestimated factors.

5. Lilies are dangerous for cats — true, and serious

The whole plant, pollen included, is severely toxic to cats and can cause acute kidney failure. It is enough for the cat to lick its fur after brushing against the flower. If there are cats, do not send lilies.

6. Plants purify the air in your home — myth, with nuances

It comes from a NASA study in sealed chambers. In a real room, ventilating is incomparably more effective. It is covered in depth in plants that purify the air.

7. Stems should be cut underwater — true

Cutting in the air lets in a bubble that blocks the stem. It is the step that makes the most difference and the one most often skipped.

8. Blue roses exist — myth

Roses do not have the gene for blue pigment. The ones on sale are dyed. The only genetically modified one is more lilac than blue. It is covered in blue, black and rainbow roses.

9. The most fragrant flowers cause the most allergies — myth

It is almost the other way around. Showy, fragrant flowers are pollinated by insects and have heavy, sticky pollen that does not travel through the air. Seasonal allergies are caused by wind-pollinated plants: grasses, plane trees, olive trees, cypresses. See flowers and allergies.

10. Tulips keep growing after they are cut — true

They can stretch two or three centimeters (about an inch) in the vase and bend toward the light. If the bouquet looks messy after two days, it is not defective: it is growing.

11. Chlorine in tap water kills flowers — myth, almost always

Chlorine levels in mains water are not a problem for most cut flowers. They are for some fluoride-sensitive plants, such as the peace lily. Letting the water stand for 24 hours solves that particular case.

12. Flowers last longer in winter — true

Cold slows down the flower's metabolism and the growth of bacteria in the water. A bouquet in July (midwinter in Argentina) can last twice as long as the same bouquet in January.