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Haddam Garden Club: Dahlias, Anyone?

Submitted by Terry Twigg.

(May 2, 2022) Even in this spring’s stubborn chill, peonies are setting their buds while roses unfurl glossy leaves along their stems, with lush flowers soon to follow.  So that’s May into June covered in the gardener’s year.  By the time spring bloom is over, the beds will be overflowing with the hot colors of midsummer.  But what’s in your lineup for late summer, and into fall?

Why, dahlias, of course.  Whether your house and garden are cottage core or formal, antique or contemporary, you’ll find varieties perfectly suited to your style—with lots of extra flowers to bring indoors.  As it happens, the Haddam Garden Club will be featuring dahlias at its Plant Sale in front of HES on Saturday, May 7, 2022, and members will be happy to tell you everything you need to know.  Trust me, you want some.

If you’ve been following the Haddam Garden Club articles, you know that I usually encourage planting natives, which dahlias decidedly are not.  But here’s why they’re safe to plant:  Dahlias are the national flower of Mexico, where they originated, so they’re hot-climate plants.  Mexico is Zone 8, while we’re still only 6b, so the plants can’t overwinter, and a plant that can’t survive the winter can’t become invasive.  Of course, native plants are always preferable as food sources for local insects, but bees and other pollinators will still feast on dahlia pollen—IF you include collarette (daisy-like) varieties.  The big fluffy varieties are useless as a food source; no insect can penetrate all those layers.  The good news is they’re apparently uninteresting to deer, too.  Every summer I plant my dahlias around the outside of my vegetable garden fence, and so far the deer have ignored them.

Dahlias have thickened roots called tubers.  They look somewhat like discouraged potatoes, and that’s not too far off, because the Aztecs, besides using the roots to treat epilepsy and the hollow stems as water pipes, also ate them.  Europeans tried following suit, but dahlias for dinner never really caught on.

The flowers did, though.  In a move repeated throughout botanical history, European explorers brought the new (to them) plants back home, discarded their native names in favor of a European botanist (the Swede Anders Dahl, whose research on pollution from fish processing plants led to the first legislation restricting the release of industrial waste into the groundwater), and immediately started hybridizing.  The results were stunning, thanks to dahlias’ remarkable botanical make-up.  While most plants have only two sets of homologous (paired) chromosomes, dahlias have eight, which allows for a seemingly infinite amount of what scientists call ‘morphological variation,’ but we know as simply astounding differences in size and shape, in every color except blue (but they’re working on it).  Today there are 82 species (estimates vary) and many thousands of varieties, with a hundred more added every year.  Tiny, near-perfect spheres of pompon or ball dahlias, 1-2 inches wide; spiky spider shapes or my favorite, the graceful waterlily style, midsize with 6” flowers on 3-4’ plants; smooth- or wavy-petaled or multicolored, all the way up to giant “dinnerplate” dahlias a foot across, growing on plants that can sometimes reach six or eight feet tall.  Like peonies, dahlias set buds in sets of three, with a pair of small buds flanking the larger, central bud.  For really big flowers, remove the twins, so that the plant will direct all its energy to the central bud.  I’m not a fan of the dinnerplates, which are so big and heavy they tend to droop, but there’s no denying the impact of a single huge bloom in a centerpiece or bouquet.

For all their drama, dahlias are surprisingly easy to grow.  Wait for the soil to warm up—about mid-May, and dig a hole in a sunny spot with rich soil and good drainage.  If yours is one of the larger varieties, add a sturdy stake now, because it’s all-too-easy to spear the roots if you wait until later in the season.  Lay the tuber on its side, and cover with a few inches of soil.  Don’t water until you see green sprouting above the surface, unless there’s a really dry spell.  Once the plant sprouts, though, be generous and consistent with watering.  Weed by hand, since any chemical that kills weeds will also kill your plant. (And bees, insects, and birds.  And possibly you.)

If you’re growing plants that are midsize or larger, pinch the stems back to a pair of leaves once the dahlias are 18” tall.  You’ll get a well-branched plant, with more flowers and sturdier stems for cutting.  Don’t forget to enter the best ones at the Haddam Neck Fair, which falls at peak dahlia season.

To save your dahlias for next year, wait until a week after they turn black and shriveled after the first frost.  Then dig them up.  Don’t be intimidated:  the roots are only a few inches below the ground, easy to lift.  To avoid mutilating the roots, dig gently, feeling your way toward the stem.  LABEL THE TUBERS, let them cure in the sun for a few days, then store in a cool, dry spot, such as your basement.

Or just leave in the ground, and plan to replenish your stock at next year’s plant sale.  You’re on your way to a happy addiction.

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