The cut foliage of many flowers does not keep as long as the flowers themselves and thus is not useful to the flower arranger. Examples are aster, marigold, and zinnia. Remove much of this foliage as you cut the flowers because it is thin and soft and wilts rapidly.
The flower arranger prizes thick, stiff, sturdy, strong-veined foliage that is long-lasting i.e. daffodil, iris, gladiolus, magnolia, cattail, peony, and sanseveria. Select old, mature leaves; avoid young, immature foliage. Place just the lower ends of these leaves in water in tall, narrow containers.
Some leaves, for example hosta, croton, English ivy, and lily-of-the-valley, should be immersed in water for an hour or so, then placed in polyethylene bags and stored moist in a cool place. Ferns are best stored out of water, but they should be kept moist and cool in plastic bags until used.