Heatwave in the flower shop: how to keep flowers alive at 38°C

The fridge is the foundation, but it won’t save you on its own

Summer is unforgiving. You open up with perfect roses in the morning, and by lunchtime their heads are hanging. Why? Because in the heat, flowers drink water faster than you can top it up.

A fridge at 4–6°C and frequently changed water are the basics. You know that, and we’ve covered it in detail in our article on how to keep flowers fresh in your flower shop. But watch out for one myth. Below 2–3°C, some sensitive flowers turn brown (“chilling injury”): they don’t freeze, but they do mark. So don’t turn the fridge down as low as it will go, thinking you’re helping. You’re not.

What to do in the first ten minutes after a delivery arrives in the heat

This is where summer is won or lost. Flowers come off the van stressed by the heat, and if they go straight into the window, you’ve as good as buried them.

Cut each stem at an angle, under cold water, and put it straight into a bucket of cold water. Give them an hour in the fridge to recover before they go out on sale. It’s the step everyone skips when it’s busy — and it’s exactly the one that shows at the end of the day.

Which flowers cope with a heatwave and which give up first

Not all flowers suffer equally. Let’s be honest about them.

First to go: peonies (they open all at once and are over in a day), tulips (they go limp and flop), hydrangeas (their heads drop within hours without water). At 38°C, these are a lottery. And gerberas, however sturdy they look, are fussy in the heat: the unsupported stem builds up bacteria quickly and the head bends over.

The ones that cope: chrysanthemums and carnations. They take the heat, last in the vase and forgive a mistake. Want a third safe option? Limonium or alstroemeria. In summer, you can put these at the front with a clear conscience.

A practical tip: if you have an event in the middle of a heatwave, say an outdoor wedding in July, build the bouquet around carnations and chrysanthemums, not peonies. The customer wants flowers that still look good on day three, not just on delivery.

The window, the air and deliveries in the heat

A shop window in direct sun is an oven. At 2pm it can easily go past 40°C behind the glass. That’s no place for fresh flowers. Full stop.

Air conditioning cools the room, but it dries flowers out if it blows straight at them, so cool the space and keep the flowers out of the draught. And keep delicate flowers well away from the fruit bowl on the front desk: apples and bananas give off ethylene, the gas that makes your flowers age faster.

Deliveries follow the same logic: a cooled vehicle, and deliver in the morning or evening, not at midday when it’s an oven outside. A bouquet that spends an hour in a car boot at 2pm arrives wilted, however well you tied it.

Order less perishable stock in summer

A flower on its way out doesn’t have to go straight in the bin: you can mark it down and sell it on (see our article on what to do with unsold flowers). But prevention beats cure. In summer, order fragile flowers less often and in smaller quantities. Fewer peonies and tulips, more chrysanthemums and carnations. You’ll lose some stock to the heat whatever you do; the question is how much. Discipline when deliveries arrive, a window out of the sun and a sensible order make the difference between a few percent wasted and a quarter of your stock in the bin.