Kate Frey: Cutting off, cutting back and crape myrtles

It is a busy time in the garden. The freshness of early summer has passed, and some plants need spent blooms removed to renew them and give the plants enough energy to continue flowering into fall. Other plants are in full glorious bloom and seem to celebrate the heat and long days of August.

Many perennials have bloomed with generosity and now have both spent blooms and new blooms on each plant, often providing a conundrum about how to approach them. Should you trim the whole plant, or laboriously trim off the spent blooms?

There are a couple ways to approach this question. Keeping spent blooms trimmed off - referred to as deadheading - encourages many plants to keep blooming. Maturing seed takes energy from the plant, and so removing old flowers lets the plant put energy into growing more flowers.

Plants like gaillardia, coreopsis, knautia, penstemon, campanula, catmint, flowering tobacco, dahlias, Salvia nemerosa and ?S. sylvestris, Gaura, and Verbena bonariensis should be trimmed back now or when plants look shabby.

If you are a person who enjoys removing individual flowers, this approach works to create a consistently floriferous scene. If you like to just get the job done, shearing all the flowers off these plants also works, but it creates a gap in time of re-bloom.

Cut plants back into strong, new growth for good re-bloom. It takes about four to six weeks for re-bloom with this method.

Petunias and lobelia may have many spent blooms and those need renewing to keep them at their best. Cut them back by half, fertilize and give extra water to encourage strong regrowth. The species perennial petunia, Petunia axillaris, is white and very fragrant. Go out in early evening with a flashlight to catch the fragrance and admire the moths (some iridescent) drawn to its intense perfume.

This is the time for crape myrtles. In just about every neighborhood, white, pink, raspberry and maroon blooms are present, undeterred by hot weather. They are the perfect small tree and are attractive in all seasons.

The pollarding, or top pruning, that many have done to them each winter is completely unnecessary unless you like the look. Just thinning out too dense branches is all the maintenance needed. Mature trees need only admiration. The white varieties are attractive to honeybees.

The chaste tree, Vitex agnus-castus, is finishing bloom. It resembles a shrub-like wisteria gone electric. Drought resistant and reveling in heat, its display of upright purple blooms are a glory to behold. Bees, native and honeybees, love this plant.

Another small tree/large shrub that revels on these warm days is the Chitalpa X taskentensis. It is a cross between the catalpa tree and the desert willow. Perfect for the sunny yard, these trees bloom for months and cast a light dappled shade. The blooms resemble large white or pale pink snapdragons. They are favored by hummingbirds and bees, and delight us for months while requiring little in terms of water or care.

Agapanthus is a common perennial in our area, and many consider it unexciting. Yet two cultivars blooming now are absolutely striking. If you like deep blues and purples you may want to take note of Agapanthus praecox orientalis “Stevie’s Wonder,” a deepest saturated navy blue. Agapanthus inaperatus nigrescens is a stunning deep violet variety. Both would look superb paired with the striking, scarlet single rose “Alatissimo.”

In the vegetable garden, gaps are appearing as broccoli, cauliflower and potatoes are harvested. These can easily be filled with bush beans, zucchini and short-season cucumbers for a fall harvest.

Kate Frey’s column appears every other week in Sonoma Home. Contact her at katebfrey@gmail.com.