Melbourne can deliver a 22 degree morning and a 41 degree afternoon in the same week, sometimes the same day. If you are marrying between December and February, heat is the single biggest risk to your flowers, and it is worth planning for rather than hoping around.
What Heat Actually Does
Cut flowers have no root system. Everything they have is what is in the stem. In heat they lose moisture through their petals and leaves faster than they can draw it up, and once a flower has passed a certain point of dehydration it does not come back.
The practical version is that flowers do not gradually look slightly worse in the heat. They look fine, and then they collapse, often quite suddenly, and usually in the two hours between the ceremony and the reception when nobody is watching them.
What Struggles Badly
Hydrangeas are the worst offender. They are essentially a sponge of water and they wilt dramatically and fast in heat. They also have the misfortune of being extremely popular.
Dahlias suffer, there's a full guide to dahlias if that's the flower in question. Sweet peas, ranunculus, poppies, and most of the delicate spring flowers are effectively finished above the mid thirties. Peonies open far too fast in a warm room and then blow out entirely.
Anything with a large soft petal and a high water content is at risk. That is most of what people put on their mood boards.
What Holds Up
Australian natives are built for this climate, which is the entire point of them, there's a full guide to natives if you want to lean into that. Banksia, kangaroo paw, grevillea, and eucalyptus foliage will look the same at 11pm as they did at 11am.
Proteas and leucadendrons are similarly robust, though worth noting they are South African rather than Australian despite usually being sold alongside natives.
Orchids, chrysanthemums, and carnations are all far tougher than their reputations suggest. Carnations in particular have been unfairly maligned for decades. Massed properly they look nothing like a petrol station bunch and they will outlast everything else in the room.
The Bouquet Is the Most Exposed Item
Your bouquet spends the day out of water, in your hands, often in direct sun during photographs. It is the hardest working piece and the most vulnerable.
A few things help. Keep it in water right up until you walk. Get it back into water immediately afterwards. Do not leave it on a car seat, which is the single most common way bouquets die, since a parked car in a Melbourne summer gets far hotter than the air outside.
Give someone the specific job of managing this. Not you, and not on the day itself. Decide beforehand.
Ceremony Timing Matters
An outdoor ceremony at 2pm in February is difficult for flowers and for guests. If your ceremony is late afternoon or early evening, the arrangements have to survive the setup and the wait, which may be the hottest part of the day.
This changes what I would build. Installations that sit in full sun for four hours before anyone sees them need a different flower selection to something going into an air conditioned room an hour before guests arrive. It is worth telling your florist exactly when things will be set up and when they will actually be seen.
Setup Timing and Access
On a hot day I want to set up as late as the venue will allow. Every extra hour in the heat costs you. Venues that insist on early access for logistical reasons are working against your flowers, and it is worth asking about this when you book rather than discovering it the week before.
Shade during setup helps more than most people realise, even for an hour.
Plan for the Forecast, Not the Average
The most useful thing you can do is agree in advance that the palette can flex if the week turns out to be extreme. Not a change of look, just a change of which flowers deliver it.
Couples who lock in a rigid flower list nine months out and refuse to move on it are the ones who end up disappointed on a 40 degree day. Couples who tell me the feeling they want and let me choose the tools usually do not notice the heat at all. You can see the full wedding flowers service for how this gets planned.
