No matter where they come from no matter their length or color there are a few things you can do to help them live their longest.
Clean water…If you wouldnt drink the water in the vase, neither will they. Roses have tiny capillaries and they get clogged very easily. Too much preservative, bacterial growth, air pockets and debris can all clog the stems. Disinfect your vase with hot soapy water and a bit of bleach, use a good scrub brush too. Bacteria can stay dormant in a vase for up to 7 years, add water and voila, a cesspool of gunk in the stems. Use cold hard water, not soft water. The deeper the water the better. Change your water every couple of days.
Cut the stems with a sharp knife or pruners on a sharp angle…NEVER USE SCISSORS! Have you ever cut a straw with scissors and the straw stays closed? thats because scissors cut by pinching and they will pinch the stems closed on a rose. The sharp angle allows the most exposure to the capillaries and more water to flow up the stem. A fresh cut of 1″ every few days will keep water flowing beautifully.
Keep them away from heat sources, fruit and direct sunlight…All these things will shorten the life of the rose. Fruit gives off ethylene gas and its a killer to flowers, thats why you should never put flowers in your fridge.
Wilting – If they heads start to wilt down, it because it cant get the water up the stem and its trying everything to open. It is dehydrating its own stem to open and get pollinated…lets face it, its always about pollination! When you see this happening its time to get drastic! Make a good cut at least 3″off the stem, fresh clean water again and cool location. If it wont come back cut it really short (short enough for a shot glass), put it on your bathroom counter, night stand, where ever a punch of colour will be nice. Hint *the shorter you cut the rose the longer it lives…the water has the least distance to travel…thats why the longer the stem you buy the longer it lasts…Longer stems = thicker stems=more capillaries=more opportunity to give them a fresh cut exposing fresh flesh and capillaries.