Adding new color to a bouquet with dye isn't new, but the technology in making it look more professional has been advancing over the years. Changing the look of flowers is now as easy as applying paint, dye, or organic materials to get the desired look.
Dirty flowers must be cleaned with warm water if you are going to use any kind of topical dye or paint. Otherwise the grime from the flower could either mix with the paint to create a discoloration, or disrupt the exterior of the paint and create ripples in the finish. If the grime is advanced, you could try using a very light organic cleaner on the plant before trying to dye it.
Using spray paint is easy, as it allows for a quick application and a broad coverage area. Spray paint can be toxic, and can damage your flower if you don't obtain the right kind. Look for a brand that is non-toxic, and is organic so that there won't be interaction with the flower. A dead flower will quickly decay- backtracking your hard work!
Application of dye directly is a good way to create custom designs.The best dye for this occasion is your average food coloring dye- which should already be safe to the plant and ready to go. You may use a small paintbrush to apply the dye if you are making an intricate design. Brush up on your color mixing skills if you need to make different shades of colors or new colors entirely.
An easier approach to dye the entire flower could be to supply the dye in a vase of water, cut the end of the flower stem, and allow it to soak up the dye. In time, the flower will slowly start to change its color to the dye of your choice. The end result dyes the entire flower, each part to a different extent depending on circulation and original color. Black dye is popular for this trick.
When your efforts are going toward a gift, or a design for a special occasion, you may want to instead take a look at paints designed specifically for flowers. These paints have all the benefits of being easy to use and looking great, but they also carry a higher price tag. The trade off is acceptable if you are intending on setting the mood for a special occasion, but for the average art project, the trade off may not be so great.
In Conclusion
Florists agree that there is nothing better than a fresh flower when you want to admire beauty. Sometimes with a little creativity, such a flower can become even more stunning with the hand of an artisan. Practice makes perfect, so don't be discouraged by an early failure.