For a low, compact centerpiece- First, find a container that you like that is waterproof. Next go to a craft store and purchase floral foam that is for fresh flowers, not silk, Usually around $2.50 a block. Also, you can choose to purchase a container that is made for foam blocks. You can also purchase water proof tape and tape the foam into place, if needed. Cut the foam to size and place it so it fits tight in the container. But, before putting foam in container, place the foam on top of a sink or bucket full of water. DO NOT force the foam under. Let it absorb water at its own pace. The water should be cold to luke warm, never too hot.
Then, find fresh flowers and greens. I suggest 3 different types of flowers, such as, fuji mums or lilies or roses or carnations as the main focal points. Gerberas do not hold well in foam. There are also tropical flowers available depending on the season. Always cut the stems at an angle to increase surface area of water absorbtion. Make sure the stems are deep in the foam so they can drink well and do not fall out.
Spread the focal flowers out equal distance apart. Then you can add spray roses, mini carns, short pieces of glads or stock, or daisies, etc. Also add filler flower like waxflower. statice or misty. Finally, you can fill in with greens, such as, leather leaf, lemon leaf, ruscus or pitt. Color is important. Be sure the colors of the flowers look well together. White lilies, pink roses and green fujis look great as a pastel arrangement. Yellow lilies, purple statice and blue iris make for a bright centerpiece. Orange, lilies hot pink spray roses, and red carnations are fun together for bold centerpiece.
If you add water as needed, then your container foam arrangement should last as long as a vase arrangement. Or you can use a cube or round short vase without foam, but then you would need to use a grid of water proof tape to hold the flowers in place.
Materials needed: Container, Floral foam, scissors or clippers, waterproof tape-optional