© Janet Davis
A friend of mine is not a gardener but, being an eligible
bachelor, gets invited to lots of dinners and likes taking cut flowers as a
gift. He asked me to recommend long-lasting flowers for bouquets. Since readers might want to gather flowers
from their own gardens, I’ll start with some pointers on when and how to
harvest blooms for 
arrangements.
When cutting flowers, use a sharp knife or very sharp pair of snips, leaving stems a little longer than you’ll need and cutting on a slant at the bottom to maximize water absorption and prevent the stem from resting flat on the bottom of the container.
The best time to pick flowers is in the evening or, failing that, early in the morning – but not in the heat of the day when the plant is already losing moisture. By cutting in the evening, you can “condition” flowers overnight, placing them in a dark, cool room and immersing them up to their necks in warm water (except for spring bulbs, nasturtium, cosmos, marigold, zinnia, liatris, rudbeckia, baby’s breath, phlox, primula, balloon flower, lavatera and sweet pea, all of which like cool water). Conditioning flowers will add substantially to their vase life.
Stems which are woody (roses, lilacs, tough-stemmed perennials, etc.) should be split, not crushed, at the bottom to enable them to take up water. Plants which form air bubbles in their stems on being cut should be re-cut under water before being used in an arrangement. These include roses, snapdragons, sweet peas, carnations, sweet William and marigolds.
All arrangements will
benefit from the addition of a floral preservative, but some plants like the
immediate addition of either a spoonful of sugar or preservative during
conditioning. China aster, nasturtium, sweet pea, petunia, blackeyed Susan,
lychnis, narcissus, poppy, verbena, peony and gaillardia are included in this
category. Narcissus or daffodils, shown at right, exude a toxin which can
damage other blooms, and are best conditioned and displayed alone.
Still others have foliage which will foul water and should have a few drops of bleach added per quart of water to check bacterial growth – calendula, petunia. Dahlia, marigold, zinnia, lavatera and mums. But all flowers should have leaves below the water line removed to keep the water clear.
Floppy flowers like tulips can be wrapped in newspaper to encourage them to condition straight, but as they age in vase, they’ll lengthen and swoop anyway (which is rather lovely, I think). If desired, heavy-headed blooms like sunflower, large zinnia and gerbera can be wired carefully up the stem with light-guage hobby wire to keep them straight. Pansies and hosta leaves should be submerged in cool water for an hour or so, before being conditioned.
Certain flowers exude sap from their stems on being cut, resulting in fast deterioration, so the stem bottom should be seared with a match or scalded in an inch of boiling water (which you carry out to the garden with you) for 20 seconds. Poppy, campanula, butterfly weed, sunflower, dahlia, lantana, heliotrope, hydrangea, lobelia, balloon flower, ranunculus, globeflower, gerbera, zinnia, globe thistle, narcissus, mums and ferns are treated this way.
To use daylily blooms for a dinner party, cut early in the morning, stand in deep water and keep them in the fridge for a few hours so they’ll stay in bloom through the evening. The fridge is also handy for any flowers that need to be cut long before a special event. I kept lily-of-the-valley in bud in the fridge for 9 days prior to a wedding, keeping a plastic bag tied over the vase to preserve humidity (something that modern fridges are good at preventing.)
Now, back to my eligible bachelor friend. Long-lasting blooms include liatris or gayfeather, gladiolus, hellebore, alstroemeria (shown at left), hydrangea, Asiatic lilies, zinnia, China aster, marrigold, stokesia, sedum, blackeyed Susan, gloriosa daisy (R. hirta selections) and purple coneflower. Statice and baby’s breath last well and, as a bonus, can be removed and used for dried arrangements later. Top prizes for staying power, however, go to lisianthus and gerbera. Properly conditioned, they’ll last for two weeks.
Adapted from a
column that appeared originally in the Toronto Sun.