Most flowers can be submerged in water, although two types do not work well. Flowers with paper-thin petals will close up under water. Flowers with a lot of pollen will cloud the water, such as lilies. You can remove pollen from the centre of large flowers. Flowers are commonly submerged in glass vases for table centrepieces. The flowers can be kept from floating by gluing them to the bottom with aquarium glue or with fishing wire and a small weight. Decorative rocks or marbles are then placed in the bottom to cover the weights or glue and a floating candle can then be placed on top of the water. There are a few flowers that work well with little effort.
Calla lilies work well in underwater arrangements as long as the pollen has been removed. Calla lilies come in a variety of sizes and keep their shape well under water. Unattended submerged flowers generally last four days with no care. Changing the water and bleaching the rocks or marbles every other day will enable flowers to last up to three weeks under water. Calla Lilies come in six ranges of colour--orange to rust, yellow to gold, mini white, pink to lavender, red to burgundy and black to deep purple.
Roses of any size, style and colour hold up well when submerged under water. Separate rose petals can also be submerged for a variety in creative centrepieces.
Orchids come in a few different styles and a nearly endless variety of solid colours and combinations of colours. Orchids do very well under water and seem to be one of the most popular choices for wedding decorations. Water acts as a magnifying glass, enhancing the beauty of orchids.
It is important to cut tulip stems under water and at an angle. Prior to submerging tulips in a centrepiece, remove the pollen from the centre to keep from clouding the water. To keep submerged tulips alive for a few days, change the water daily.
Hydrangeas come in a large variety of colours, even from one plant. Hydrangea colour varies according to the acidity of the soil and the amount of direct sunlight. For example, a blue hydrangea plant can produce several shades of blue, purple, and pink. A blue hydrangea requires a high soil acidity, so if the soil is not acidic enough for blue, the flowers produced will be from lavender to pink. Hydrangeas of any colour hold up well under water.