Should You Trim Spent Blooms?

Dear Garden Problem Lady

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Will cutting spent blooms on my pinks encourage reblooming?

Deadheading dianthus – and most other annuals – allows the plants to direct their energy into growing more blossoms and denser foliage instead of producing seeds. Or, with other annuals, such as zinnias, just picking the flowers can spur the plant to create more flowers. Some perennials will do the same — Bleeding heart, Phlox, Delphinium, Lupine, Salvia, Veronica, Shasta daisy, Yarrow and Coneflower. As plants fade out of bloom, you stimulate more flowers by pinching or cutting off the stem below the spent flower and just above the first set of full, healthy leaves.

How about perennial geraniums, such as Johnson’s Blue?

After blooming, ‘Johnson’s Blue’ can look pretty floppy and scraggly with numerous bare, branched flower stems.  Simply shear it back with a garden shear, and fresh foliage will emerge as well as additional blooms. Johnson’s Blue’ is a perfect woodland garden plant if the site is not too shady, and will generally live for ten years or more.

I sheered back my sweet Alyssum because it was on its way to growing seeds. I hoped it would re-bloom, but it has not done so. It looks healthy, bushy and green – but of course much smaller. Have I killed its chance for more flowers? 

Not at all. A thorough sheering off will spur more blooms. Alyssum sags a bit in the hot summers of DC. Shear the whole plant back by about one-half its height, and keep it well watered. New flowers should bloom in just a week or two.

This June, all over the city, the hydrangeas have bloomed so beautifully, lushly, and fully. If you pick them, will they keep on blooming – or bloom again – this year?

When dead-headed, Hydrangeas will not re-bloom, but deadheading will clean up the plant and help strengthen it for next year.

A friend says Cedar Rust causes the brown splotches on the leaves of my American Hawthorn tree. Is this serious?

This so-called “Rust” is a fungus that needs two different hosts – often a Juniper (Cedar) and a second tree, such as a pear, or Hawthorn. The brown splotches on your Hawthorn will produce spores on the undersides of the leaves that will reach the other host and infect it. This Rust will probably not kill either tree. Consider living with the disease, or prune out diseased branches — or you can try to spray the leaves of your Hawthorn with Daconil before spring blooming. 

The Capitol Hill Garden Club convenes public meetings again on September 11 at 6:45 pm at the NE Public Library, corner of Maryland Ave. & 7th St. NE. Meetings are free and open to all. Membership details: capitolhillgardenclub.org.