Dahlia
Bold, dinner-plate blooms in every color of the spectrum make dahlia the undisputed showstopper of the late-summer garden.
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The Garden's Grand Finale
Dahlias are native to the highland meadows of Mexico and Central America, where they grow as perennials in mild, frost-free climates. Aztec peoples cultivated them for food, medicine, and ceremony long before Spanish botanists carried them to Europe in the late 1700s. Today, the genus encompasses thousands of named cultivars ranging from tiny pompon types just 2 inches across to the legendary dinner-plate forms that can exceed 12 inches in diameter.
Few plants deliver such a long season of extravagant color. Dahlias bloom from midsummer and keep going hard right up to the first killing frost, filling a gap when many spring flowers have long faded. Their forms are wildly diverse - cactus, waterlily, collarette, anemone, and ball types, to name just a few - making them endlessly collectible for gardeners and florists alike.
Planting & care
Plant tubers outdoors after all frost danger has passed and soil has warmed to at least 60 degrees F. Set them 4-6 inches deep with the eye facing up, spacing large varieties 18-24 inches apart and compact types 12 inches apart. Choose a spot with full sun (at least 6-8 hours daily) and rich, well-draining soil amended with compost. Hold off watering until sprouts emerge; then water deeply once or twice a week, keeping moisture consistent but never waterlogged.
Pinch out the central growing tip when plants reach 12 inches tall to encourage bushy growth and more blooms. Stake tall varieties early before stems become heavy. Feed every 3-4 weeks with a low-nitrogen, phosphorus-rich fertilizer to fuel flowering rather than leafy growth. Deadhead spent blooms regularly to keep new buds coming. In zones colder than Zone 8, dig tubers after the first frost blackens the foliage, cure them for a few days, and store in a cool, dry, frost-free location over winter.
Pinch Early, Bloom Often
Removing the first central bud - a technique called disbudding - feels counterintuitive, but it signals the plant to redirect energy into side shoots, resulting in significantly more flowers over the whole season. Do it once when plants are young and you will be rewarded with a far bushier, more floriferous plant by midsummer.
How much sun does Dahlia need?
Dahlia grows best in full sun.
How often should you water Dahlia?
Give it about 1-2 in per week.
When is Dahlia ready to harvest?
Dahlia is usually ready in blooms midsummer to first frost; cut flowers when outer petals are fully open.