To deadhead or not to deadhead

Lots of flowers in my new bed means lots of decisions about whether to deadhead, or remove spent blossoms. 

Ox-eye sunflower and butterfly weed

Conventional garden wisdom rates deadheading as a necessity. It neatens up the garden, and more importantly, it’s intended to trigger the plant to make more flowers instead of channeling its energy into transforming fertilized flowers into seeds.

    As the flat yellow yarrow blossoms (Achillea ‘Coronation Gold’) turn brown, should I leave them to go to seed? 

Yarrow flowers this week

A trusted reference on perennials, Tracy DiSatabo-Aust’s The Well-Tended Perennial Garden, firmly dictates deadheading these flowers and promises they’ll be followed by new blooms from lateral buds and possibly from the plant’s base too.

Deadheading-photo Helen Harrop/Flickr through a Creative Commons license

    More flowers will provide more pollen for native insects. Jessica Walliser, in her book Attracting Beneficial Bugs, explains that native common yarrow (Achillea millefolium) is favored by lacewings, ladybugs, syrphid flies, parasitic wasps, and damsel flies—all predators that consume leaf-eating insects, keeping the garden’s insect population in balance.

Green lacewing, a beneficial predator

     My yarrow is related to fern-leaf yarrow, a European introduction (Achillea filipendula). I hope it attracts most of the same bugs as the native. Jess observes minute pirate bugs, very active predators, living in the flowers of this cultivar. Insects benefiting from the flowers add reasons to go ahead and deadhead the yarrow in hopes the plants will flower again.

    On the other hand, in Gardening for the Birds, George Adams writes that many birds eat the seeds of common yarrow. He adds that some cavity-nesting birds harvest its foliage to line their nests. It seems that the strongly scented foliage repels parasites, so by making this choice, the birds as “self-medicating.” 

My yarrow's fern-like leaves

    But George Adams also notes that birds feed on the insects that are drawn to yarrow flowers. This summer and last, following his advice, I’ve put a moratorium on filling bird feeders with seed. This way birds are supposed to turn their attention to eating seeds and insects they find in the yard, rather than just birdseed I put out.

    Last summer I noticed that birds continued to visit the yard without finding seed in the feeders. One side benefit was the disappearance of European house sparrows, nonnative birds notorious for muscling aside native species and hogging all the food. I guess the sparrows aren’t interested in foraging for food and prefer to go where the pickings are lusher.

European house sparrow

    This is one of those environmental decisions with pros and cons on both sides. I can deadhead to offer more flowers for the insects, or let the flowers go to seed for the birds. If I deadhead, I should get to enjoy some more of the pretty yarrow flowers.

'Coronation Gold'

     You can probably tell which way I’m leaning. I think I’ll deadhead now and call it a scientific experiment. I'll see how many more blooms I get after deadheading. I’ll plan to let the flowers go to seed at the end of the summer, leave them standing, and see if I spot birds eating the seeds. That way we all win.

Common yarrow