Floral Designers use three types of Floral Foam:
Floral foam is not a substitute for water but merely a water source.
Arrangements fade quicker designed in foam than in water. As little as 10% moisture loss will cause wilting.
If the Floral Foam dries out it pulls the water from the flower stems.
Top up the water that evaporates or is absorbed by the blooms. Green floral foam can be topped up by pouring water into the container. Rainbow Oasis needs to be topped up by pouring water on to the foam where the stems are inserted into the foam
I always cut a small V shape into the foam at the side of the design where it would not be seen to give the water a channel to run down into the container rather than spill over the edge of the container.
The wet floral foam crumbles easily and stems- especially heavy stems will destroy the foam as you insert them. Make a cage for the wet foam out of wire to protect the shape. If you want to re-insert a stem do so at a slightly different position and do not simply press the stem into the same hole. This way you insure that your stems will have access to water.
Do not use the Floral Foam block more than once. The left over pieces can be used to build up a base in a large container to place fresh Floral Foam on.
If you have large chunks of unused soaked Floral Foam left over place it in a plastic bag to keep moist to use later. Floral Foam that has been soaked and left to dry out will not take up sufficient water after a second soaking. If you have to re-soak Floral Foam try soaking it in really warm water but make sure you leave room in your container for additional fresh water.
Protect precious containers from rust or water damage by lining the container with thick plastic before adding the Floral Foam. Terracotta and other unbaked clay or paper pots should also be lined to prevent damage.
Using Floral Foam is sometimes the only logical mechanic for a design, it is really a pity that we do not have a more environmentally friendly foam, yet.
As wet foam it is a rather wasteful product- "use once and throw away" does not feel like a sustainable solution for Contemporary Design.
The real potential, for me, lies in Floral Foam as a convenient sculpting medium. It is fantastic to carve into re-usable shapes.
It is easy to alter the shapes; it is light weight, is available in gorgeous colours, can be glued, pined, skewered and suspended for limitless design possibilities.
But seeking an alternative to use as mechanic rather than wet foam is another great opportunity for Contemporary Designers to be innovative.
As a substitute for keeping flowers in place use a Kenzan or test tubes. I even up-cycle drinking straws and fill reeds with water, have a look at my Tool Bag and follow some of the links to the Tutorials from there or simply wad wire, moss or twigs to create a flower frog, insert test tubes into the foam or work with structures.
Flowers do better placed directly in in water rather than foam.
Remember: Floral Foam is not compostable. Used foam can only become trash- it is possible re-use used blocks of Floral Foam to build up platforms inside large containers but you can not re-use them as a floral water source