Well I got a luuuurvely bunch of roses for my birthday a couple of days ago, but of course the weather’s pretty hot at the moment and my flowers aren’t looking too good 
So does anyone have some tips or advice for making my roses last for a little while longer? It would be greatly appreciated!! 
I can’t help with making them stay fresh - they are cut from their root system and won’t be able to survive long anways, but what I do with roses if i want to keep them is dry them. Hang them upside-down in a dark space (e.g. a closet) and forget about them for a couple of weeks. Sooner or later they will all dry up, and although they will be kind of darker than they were and more fragile, they should keep their shape.
I have a single dried rose above the door between the kitchen and dining room, as well as one as a centrepiece on the table (unless we get something else temporaily). The first roses my SO ever gave me are in a vase in our bedroom, on the dresser, and I have another bouquet on a shelf of a display bookcase. Those are all the roses I’ve ever received, and they add a bit of colour to otherwise bland places, even when they’re dried.
I’m not big into flowers, so I’m not sure if this works with roses, bu if you add lemonade to the water in the vase you are standing them in, the sugar will keep them fresher for longer.
The advice I’ve always gotten is to cut the stems underwater with a very sharp knife, not scissors. I think this allows the stems to absorb water better than if the stems are sheared or crushed or cut dry. My main squeeze adds that puttting them in 7 up helps too.
Cut at an angle and do add the 7 up. It works.
Viagra. Seriously.
A few years ago, I had jury duty. Upon learning one of the potential jurors was a florist, the judge asked “How can I keep cut roses looking nice longer?” He said that you should not keep them in a hot room, but other than that and making sure they have water, nothing much works reliably. If you want nice looking flowers that last, buy carnations.