9. Give the plant a nice shearing
Most flowering bushes can be persuaded to have a second––or even a third––round of flowering if the climate remains favorable. Even flowering plants like Bee balm, Rudbeckia and Goldenrod that may not produce flowers a second time look better if they are pruned hard at the end of their flowering. The lush new growth can look just as attractive.
Cutting back the growth by one-third usually helps many flowering shrubs to grow a new set of stems tipped with flower buds. Some plants like Foxglove, Delphinium, Pincushion flower, and Salvia have a basal tuft of foliage from which tall flower spikes arise. All their flowering stalks should be removed before new ones can sprout from the base. Coreopsis, Columbine, Stoke’s aster, and Crane’s bill Geranium may put up new growth and offer another set of flowers if you trim them down almost to the ground.
10. Boost flowering with a shot of high phosphorous fertilizer
A good pruning has to be followed by a good feeding to coax the plants to flower again. The second flush of flowers may not be as fabulous as the first one, but they help extend the flowering season by a few weeks. Avoid nitrogen-rich fertilizers this time because there may not be enough time for vegetative growth before the weather turns. Give a high-phosphorous formula to let the plants focus on flowering. The flowers would be borne on shorter stalks and may be smaller in size and fewer in number.
11. Staggered planting
This is mainly useful for bulbs which bloom only once in a season. To keep your garden in flowers throughout the season, you should plant several batches of bulbs at weekly or biweekly intervals. Mixing early flowering cultivars with late-flowering ones also help extend the season.