COMPLETE GUIDE
TO DAHLIAS
Dahlias are native to the mountainous regions of Mexico and Central America, where they were cultivated for ornamental and medicinal use. Introduced to Europe in the late 18th century, they quickly gained popularity for their vivid colors and wide range of flower forms, leading breeders to develop thousands of cultivars. Today, dahlias are valued for their diversity, with blooms ranging from compact pompons to expansive dinnerplate flowers, displaying petals in everything from soft pastels to bold color combinations. Their long blooming season and strong visual presence continue to secure their place among the most popular ornamental flowers.
GROWING DAHLIAS
Dahlias reward gardeners with months of flowers, but strong performance begins with proper timing and planting conditions. Warm soil, abundant sunlight, and good drainage help establish healthy plants that produce stronger stems, larger flowers, and heavier bloom production. A little planning early in the season often makes a significant difference later.
When to plant:
Plant dahlia tubers after all danger of frost has passed and soil temperatures have warmed to approximately 60°F. In the Pacific Northwest and similar climates, planting often occurs from late April through early June, depending on weather and local conditions. Planting too early in cold, wet soil can delay growth and increase the risk of rot.
Where to plant:
Choose a location receiving 6–8 hours of direct sun daily, though additional sunlight often produces stronger stems and heavier flowering. Good airflow around plants helps reduce disease issues and promotes healthier growth throughout the season. Taller varieties also benefit from some protection from strong winds.
How to plant:
Plant tubers approximately 4–6 inches deep, positioning the eye upward or slightly angled. Space plants according to mature size and install support stakes at planting time for taller varieties to avoid disturbing roots later. Unless soil is unusually dry, avoid heavy watering immediately after planting, as cool wet conditions can encourage tuber rot.
Soil:
Dahlias perform best in fertile, organically rich soil with excellent drainage. Heavy clay soils may benefit from compost or organic matter to improve structure and prevent excess moisture around developing tubers. Soil with a pH around 6.5–7.0 supports good nutrient uptake and healthy growth.
Spacing:
Provide adequate spacing between plants to improve airflow and reduce overcrowding later in the season. Good circulation helps minimize fungal problems and allows plants room to fully develop.
Important note:
More tubers are often lost from planting in cold, wet soil than from waiting an extra week or two for warmer conditions.
Dinnerplate & Giant Flowered Dahlias
Dahlia 'Baarn Bounty'
Deciduous perennial with large lavender pink waterlily form blooms creating soft romantic color through the season. Forms a sturdy upright habit and grows 3 to 4 feet tall. Ideal for borders, cutting gardens, and late season displays. Zones: 8 to 11.
Dahlia 'Swan's Sunset'
Deciduous perennial with deep green foliage and richly blended sunset tones of orange, coral, and gold. Forms a sturdy upright habit and grows 3 to 4 feet tall. Ideal for borders, cutting gardens, and seasonal displays. Zones: 8 to 11.
Dahlia 'Penhill Dark Monarch'
Deciduous perennial with enormous ruffled blooms blending raspberry pink, mauve, and smoky purple tones. Forms a tall upright habit and grows 4 to 6 feet tall. Ideal for borders, cutting gardens, and statement plantings. Zones: 8 to 11.
Other Notable Dinnerplate & Giant Flowered Dahlias
Dahlia 'AC Jeri': Enormous soft pink blooms with gently curved petals
Dahlia 'Belle of Barmera': Giant peach-apricot flowers with broad, layered petals and warm sunset tones
Dahlia 'Bonaventure': Large creamy white blooms brushed with soft lavender-pink tones
Dahlia 'Nick Sr.': Oversized rich burgundy-red flowers with dramatic color
Dahlia 'Sherwood’s Peach': Large peachy-pink flowers with softly blended coloration
CARING FOR DAHLIAS
Once dahlias begin actively growing, regular maintenance encourages stronger plants, better branching, and a heavier flower display. Consistent watering, proper feeding, and a few simple seasonal tasks help plants remain vigorous and productive well into fall.
Watering:
Wait until foliage emerges before beginning regular watering. Once plants become established, deep watering encourages stronger root systems and helps plants tolerate summer heat more effectively. Dahlias prefer consistent moisture but dislike saturated conditions.
Fertilizing:
Dahlias benefit from fertilizers lower in nitrogen and higher in phosphorus and potassium, such as 5-10-10 or similar bloom-promoting formulas. Excess nitrogen can produce large amounts of foliage at the expense of flowers. Feeding every 3–4 weeks during active growth often supports stronger bloom production.
Pinching and branching:
When plants reach approximately 18–24 inches tall, cut or pinch the main stem back to roughly 12–18 inches, removing the dominant central growth point. This redirects energy away from maintaining a single heavy stalk and encourages branching, creating fuller plants with more flowering stems and significantly greater bloom production later in the season.
Staking and support:
Many taller dahlias benefit from support to prevent stems from bending or breaking beneath large flowers. Installing stakes early helps plants grow naturally around supports and minimizes root disturbance.
Deadheading and cutting:
Removing spent blooms encourages continued flowering and keeps plants looking tidy. Dahlias respond particularly well to cutting; harvesting long stems often stimulates additional blooms and encourages stronger branching.
Pests and diseases:
Slugs, earwigs, aphids, spider mites, and powdery mildew can occasionally affect dahlias. Good airflow, healthy soil, and regular observation help identify problems before they become severe.
Important note:
The more flowers you cut, the more blooms many dahlias produce. Frequent harvesting often results in longer stems and increased flowering.
Unusual & Distinctive Dahlias
Dahlia 'Picasso'
Deciduous perennial with deep green foliage and bold white blooms brushed and splashed with vivid burgundy. Forms a sturdy upright habit and grows 3 to 4 feet tall. Ideal for borders, cutting gardens, and seasonal displays. Zones: 8 to 11.
Dahlia 'Lake Hills Sunset'
Deciduous perennial with distinctive anemone form blooms blending apricot, peach, and coral sunset tones. Forms a sturdy upright habit and grows 3 to 4 feet tall. Ideal for borders, cutting gardens, and seasonal displays. Zones: 8 to 11.
Dahlia 'My Hero'
Deciduous perennial with dramatic raspberry blooms displaying lighter reverse petal coloring creating two toned contrast. Forms a sturdy upright habit and grows 4 to 5 feet tall. Ideal for borders, cutting gardens, and seasonal displays. Zones: 8 to 11.
Other Notable Unusual & Distinctive Dahlias
Dahlia 'Checkers': Dramatic red and white bicolor blooms with contrasting petal coloration
Dahlia 'Fuzzy Wuzzy': Shaggy, heavily fringed pink and white patterned petals
Dahlia 'Awe Shucks': Creamy yellow blooms splashed and streaked with coral-red brushstrokes
Dahlia 'Dutch Carnival': Rich crimson-red blooms brushed with golden-yellow petal edges and highlights
Dahlia 'Tahoma Moonshot': Star-shaped blooms with narrow burgundy petals
DIGGING, DIVIDING & STORING DAHLIA TUBERS
For many gardeners, overwintering tubers becomes one of the most important parts of growing dahlias. In colder climates, tubers are often lifted and stored to protect them from freezing temperatures and excess winter moisture. Proper storage helps preserve favorite varieties and allows plants to return year after year.
When to dig:
Wait until frost blackens foliage and plants begin entering dormancy. Many gardeners allow plants to remain in the ground for an additional week or two afterward so tuber skins can mature and toughen before lifting.
How to dig:
Cut stems back to several inches above the ground and carefully loosen soil well outside the root zone to avoid damaging tubers. Lift the entire clump gently and remove excess soil. Label varieties immediately before they become mixed.
Dividing tubers:
Tubers may be divided in fall or spring depending on preference. Each division must contain a viable eye attached to a portion of crown tissue to produce growth the following season.
Storage:
Allow tubers to dry briefly before storing them in slightly moist vermiculite, peat, wood shavings, or similar materials. Store in a cool, dark location around 40–50°F, avoiding freezing temperatures or overly warm conditions that encourage premature sprouting.
Monitoring during winter:
Check tubers periodically throughout storage. Remove any showing signs of rot and lightly mist excessively dry tubers if shriveling becomes severe.
Important note:
Label tubers immediately after digging. Once stored, many varieties become nearly impossible to distinguish from one another.
Cut Flower Favorites
Dahlia ‘Mai Tai’
Deciduous perennial with deep green foliage and blooms blending coral, peach, apricot, and golden tones. Forms a sturdy upright habit and grows 3 to 4 feet tall. Ideal for borders, cutting gardens, and seasonal displays. Zones: 8 to 11.
Dahlia ‘Labyrinth’
Deciduous perennial with enormous ruffled blooms blending blush pink, peach, and creamy apricot tones. Forms a tall upright habit and grows 3 to 4 feet tall. Ideal for borders, cutting gardens, and statement plantings. Zones: 8 to 11.
Dahlia 'B-Man'
Deciduous perennial with deep green foliage and richly saturated raspberry blooms, gradually lightening toward the tips. Forms a sturdy upright habit and grows 4 to 5 feet tall. Ideal for borders, cutting gardens, and bold seasonal displays. Zones: 8 to 11.
Other Notable Cut Flower Favorites
Dahlia 'AC Andromeda': Large creamy white blooms with luminous buttery centers
Dahlia 'All That Jazz': Warm peach, coral, and golden-apricot blooms
Dahlia 'Andy’s Legacy': Warm coral-pink blooms brushed with apricot and soft peach tones
Dahlia 'Randi Dawn': Soft blush pink blooms with a pastel appearance
Dahlia 'Raspberry Punch': Vivid raspberry-pink blooms with bright saturated color
GARDEN TOURS • OREGON
Swan Island
Dahlias
Swan Island Dahlias showcases expansive fields filled with thousands of blooming dahlias in every color and form, set within a working flower farm environment that offers sweeping views, seasonal displays, and a vibrant late-summer destination for garden enthusiasts and photographers.
Dahlia Flower Forms
Dahlias display an impressive range of flower forms. From small, tightly patterned blooms to large, fully layered blossoms, these forms create varied visual effects in the garden. This diversity allows dahlias to suit many planting styles, providing bold focal points, soft texture, and abundant color in borders, cutting gardens, and seasonal displays.
