Pinching for Long Stem Cutting Flowers
Pinching is a useful technique to get long straight stems from branching plants that produce multiple blooms. By cutting out the central growing tip, you force the plant to grow from the base providing many more usable stems.
Summer favorites of zinnia, amaranth and celosia are all branching plants that benefit from pinching early in their lives to produce more stems. The black eyed susan grow from the base of the plant so there is no need to pinch.
The benefits of pinching include more stems of flowers, bushier plants, longer stems, control over bloom and stem size, and less junctions that weaken a harvested and stripped stem.
To actually pinch:
Pinch young plant 8”-12” tall
Use sharp, clean snips
Cut 3”-4” off the central stalk just above a set of leaves
Take care in not nicking stem or leaves
Lisa Ziegler from The Gardeners Workshop has this simple video of how to do it.
Hardy Annual Branching Plants
Chinese Forget Me Nots
Lambada Bee Balm
Tender Annual Branching Plants
Perennials and Bulbs that branch and can be pinched:
Most perennials and bulbs grow from the base. The following should be pinched but can be deadheaded or harvested at the ground level to promote more stems:
Don't Pinch These Types of Plants
Single stems - tulips, sunflowers, stock, Bombay celosia, gladiola
Basal branching - lisianthus, statice, iris, yarrow, rudbeckia (but harvesting or deadheading spent blooms at the base of the stem encourages more growth)
Don’t deadhead plants that you want a seedpod from like nigella