is there any way to keep my flowers looking fresh all day?

Your florist should have good quality flowers.  Give you instructions on flower care and no extreme heating changes.  

To make sure your flowers look the best all day firstly make sure you find a florist who knows what they are doing. By this I mean, they will have an understanding of what flowers 'hold up' the best for a day out of water, and advise you accordingly.

They will also specially prepare certain flowers ready for a tough day, this may be as simple as wireing and other 'tricks of the trade'.

Once the flowers are in your hands there are a few things you can also do to help.

Keep them in a cool place until needed, maybe in water if natural stems.

Keep out of direct sunlight and away from a heater.

Keep somewhere that they will not be knocked like in the laundry.

While at your wedding and reception, simply be gentle with the flowers (until you need to throw the bouquet).

Place the bouquets on the bridal table or even better have vases of water ready for the bouquets to sit in.

We always give care instructions with wedding flowers to ensure that you know how to keep them fresh for the day, depending on the flowers you have chosen, will depend on the care and how delicate they are, example, native flowers will stay beaufitul with minimal care, where as roses, peonies etc will need more attention, I hope this helps with your enquiry. From Rainflowers Florist.

Flowers in season should firstly be selected. Your florist can suggest the best flowers to use. I would also avoid keeping them in direct sunlight and heated rooms. When travelling between ceremony , photo locations and reception you could also keep the flowers in the box provided by your florist and cover them with tissue paper, then light moisten the tissue with a spray bottlef water, this will help keep the flowers hydrated, and also avoid handling them too much. You may want to have a vase at the ready at you reception to pop the bouquets into, ( good idea if you are planning to have your bouquet preserved).

Choose the apropriate flowers for the season, for example if it is summer, choose long lasting tougher flowers. You can also recut the stems after the ceremony and photo's and place the bouquet's in fresh water (for example on your bridal table or else where at the recpetion). This will revive them after being out of water for so long. Continue to recut the stems every couple of day's for even longer lasting flowers!

Start by using a florist with a good reputation for quality. By selecting quality blooms you're already on the way to having them look fresh all day. Also be sure to ask your florist for advice, especially if you're getting married in the warmer months, as to which flowers are going to hold up better for you.
Limiting their exposure to direct sunlight and extreme heat will also keep them looking fresh. If its going to be a hot day or you're worried about them, placing the stems of your bouquets into water throguhout the day will help them but you'll need to be sure that you give the stems a bit of a trim before hand so they are able to drink up the fresh water.
One of the easiest ways to keep them looking fresh all day is to have them delivered to you closer to your ceremony time still allowing for time to have photographs with them before your ceremony.