Ciscoe Morris, Seattle Times garden writer, offers tips on renewing leggy annuals and perennials; it's time to let broad-leaved evergreens begin hardening off for winter; and a number of annuals including marigolds, zinnias, salvias and geraniums will stop blooming and go to seed if you do not remove the old flowers.
Around this time of year, annuals and perennials in containers and hanging baskets can become leggy with flowers only at the end of long branches. At the same time, overly rambunctious growers can overwhelm neighboring plants, crowding or even suffocating them for lack of light and air.
Renew leggy annuals and perennials by cutting back about half of the stems 2/3rds of the way to the base now. When those stems grow back and begin to bloom in about two weeks, cut back the remaining stems the same way. While you’re at it, cut back aggressive growers as far as necessary to give surrounding plants space for healthy growth.
Provide adequate water and keep fertilizing regularly with a well-balanced, soluble flower food. Your containers should look great all the way through late-October.
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All shrubs, especially broad-leaved evergreens such as rhododendron, pieris, camellia, hebe, etc., need to calm down, stop growing and harden off to get ready for the winter cold. Fertilizing after mid-July can cause them to continue growing into fall and winter, leaving them susceptible to catastrophe if we get an early freeze such as occurred last November.
The only exception, as far as I’m concerned, is the rose. I work in a last shot of alfalfa meal and rose food into the soil around the drip line in mid to late August. To me it’s worth the risk because feeding at that time encourages roses to bloom beautifully in September and October.
It’s true that if you follow my advice and fertilize in August, you could lose your rose if we experience another November freeze. But, oh, la, la! Think how much fun it will be to shop for a new one!
a wild banshee
A great number of flowering annuals such as the marigold, zinnia, salvia, geranium and cosmos will stop blooming if you allow them to go to seed. The same is true of repeat blooming perennials such as Dahlia, Armeria (thrift), Scabiosa, some types of Kniphofia (torch lilies) and Gaillardia.
These plants know they’re on Earth to reproduce, and if you leave the spent flowers on too long, they’ll form seed. Knowing that they already raised a family, they’ll kick back, get a good tan, snack on fertilizer and do nothing else for the rest of summer.
To keep them blooming, make a habit of pinching or pruning off the old flowers on a regular basis. Repeat blooming roses also require deadheading to keep them blossoming all summer long. Always cut back to an outward facing branchlet with five leaves. There are hormones there that will cause a new rose to grow much sooner than if you cut to one with only three leaves.
There’s no harm in waiting to cut off a cluster until the entire bunch is over the hill, but if you remove individual spent blossoms every night, your garden will look its best because visitors will never see a spent rose on your plant.
Ciscoe Morris: firstname.lastname@example.org. “Gardening with Ciscoe” airs at 10 a.m. Saturdays on KING-TV.