By: Rachel Link
If you think of your garden as a beautiful ballet of plant life coming together to create a picturesque performance of colors, sights, and smells, consider the dahlia your principal dancer. With dainty petals that contort to form tutu-like flowers, tall, slender stems that defy gravity and an enchanting array of clear hues, the dahlia gives any garden an “it” factor.
Dahlia grower extraordinaire and great friend of PHS Jennie Love shared dahlia tips with PHS’s GROW Magazine, based on experience cultivating these flowers at her Philadelphia organic flower farm.
Jennie tells PHS that dahlias are not just divas because of their star quality. Since they prefer mild temperatures and moist conditions to thrive, they can be tricky to grow in hotter climates -- but there are certain varieties that work well for beginners. If you’re already planning for next year’s growing season and want to start with something a little more manageable, Jennie recommends dahlias in the decorative class, which are typically easier to grow. ‘Amber Queen,’ ‘Bride to Be,’ ‘Cafe au Lait,’ ‘Ginger Snap,’ and ‘Uptown Girl’ are just a few examples of this variety that perform great and are easy to work with.
If you didn’t plant dahlias in the spring, you can still enjoy dahlias this season by purchasing already-grown beauties from your local flower shop or garden center. They don’t travel well, so buying local is best.
Dahlias can often be finicky, requiring careful attention for successful blooms. If you’re looking ahead to next year, start by ordering your tubers in winter to arrive in mid-May for your first bloom in mid-July. Popular varieties sell out quickly, so order early for best selection.
Like the solo performer they are, Jennie Love recommends treating dahlias like production crop, dedicating a separate bed to grow them. Since dahlias are heavy feeders, starting with rich, fertile soil is extremely important. You can learn more about soil building in this PHS-exclusive gardening guide.
Plant your tubers (or cuttings, which Love praises for performing better and better with each season!) 18 inches apart in double rows, staking and twining as they gain height.
Overwatering can be a common mistake – you’ll need to wait until sprouts appear above the ground to start deep watering underground, and not more than a few times per week!
Pinching dahlias is important for sturdy plants that won’t topple over. You’ll want to pinch or cut the center shoot when your plant is 18-20 inches tall or have six sets of leaves. This should be done again in midsummer.
Most dahlia varieties need staking to support their heavy top growth. Wooden or bamboo stakes are fine, but the sturdiest stakes are ¾" copper plumbing pipe, which come in 5’ lengths -- perfect for supporting many of the taller types.
When you’re ready to harvest your dahlias, these divas expect you to get out of bed nice and early. Jennie recommends cutting the flowers before sunrise – or at least before the sun has a chance to touch them. You should store dahlias in cold water in a cool, dark place for most if not all of the day (remember, they don’t perform well in the heat!) When you’re ready to put them in an arrangement, make sure to cut another inch off the stem. Cut dahlias will add some razzle dazzle to any bouquet or table display for up to 5 days after cutting.