Prior to collecting material get your gardener to spray an insecticide to prevent pollen beetle and other insects being imported.
All flowers will last longer if a foxglove is included in the arrangement. If they are not desired or available make a tea by pouring boiling water on foxglove leaves. When cool use the liquid with water.
For delphiniums and larkspur add sugar don’t bother with the old Wive’s idea of an old penny (give it to the gardener).
For daffodils and narcissus add charcoal or camphor to the water and preferably keep them from other flowers.
Topmost buds should be nipped from gladioli, snapdragons and delphiniums.
Heathers without water will last for weeks in the house without withering or dropping needles.
Many spring flowering shrubs will last longer if picked in bud rather than full flower and stood in hot water first. Try this with Forsythis, Wintersweet, Witch hazel and willows.
If flowering shrubs must be used the whole shoot should be taken down to two buds above old wood.
Leave enough leaf material for plants to regenerate.
Old flowers may be about to set seed and will not last long in the arrangement.