Dahlia

( DAHL - yuh )

At-A-Glance Information

Dahlia is a very commonly known genus of flowering plants, prized for their intricate, colorful blooms. They are native to Mexico and Central America, and the genus has a great deal of variety in flower forms due to its genetic diversity. Plants are typically shrubby, sometimes upright, and can also be tree-form. Grow Dahlias as members of cut flower gardens, in mixed beds and borders, as specimen trees, in containers, or simply to add pops of unusual, bright colors in the landscape. Take care when planting these bloomers in the landscape or keeping them indoors in flower arrangements, as plant parts are toxic to humans and pets if ingested. Skin contact can also cause dermatitis, especially in sensitive individuals.

Dahlia Species and Varietals

Dahlia includes between 40 and 50 distinct species and is a member of the plant family Asteraceae. The genus is named for Anders Dahl, Swedish botanist and student of Carl Linnaeus. The best growing zones for Dahlia plants are USDA hardiness zones 3-11, though this varies somewhat depending on the species cultivated. For more information, refer to the descriptions below. To find your zone, click here: Zone Map

Dahlia campanulata (Weeping Tree Dahlia)
Native to the states of Guerrero and Oaxaca in Mexico. Flowers are large and white with reddish-purple centers, and droop from their attachments, creating quite a show for visitors underneath the canopy. These plants are hard to find in the nursery trade, and are considered rare in cultivation. Plants grow from underground tubers in the spring, and after flowering shed all of their above-ground parts. Weeping Tree Dahlia reaches about 8 feet tall when in bloom and grows well in USDA hardiness zones 8-10.

Dahlia coccinea (Red Dahlia, Scarlet Dahlia, Wild Dahlia)
Flowers produced by this species can be red, yellow, or orange. These plants are commonly used as garden ornamentals, and are native to Mexico. The tubers of these plants were used historically as a food source by the Aztecs. This species grows well in USDA hardiness zones 7-11.

Dahlia imperialis (Bell Tree Dahlia)
Native to the Americas, these fast-growing plants reach between 26 and 33 feet tall at maturity. They grow well in USDA hardiness zones 8-11. Each growing season, canes are sent up from a tuberous root. Flowers are produced in fall, and are lavender to mauve-pink in color. This species is considered invasive in parts of Australia and California.

Dahlia merckii (Merck's Dahlia)
These plants reach 8 feet tall, and has divided leaves. Flowers emerge in late summer and fall, and come in shades of lilac, white, and pink. These plants are native to Mexico, and are hardy only in mild-winter areas. Merck's Dahlia grows well in USDA hardiness zones 7-11.
Dahlia pinnata (Dahlia x pinnata) (Garden Dahlia)
This is the type species of the genus Dahlia, and is widely cultivated as an ornamental in gardens across the globe. It forms from a rhizome root, and typically reaches between 28 and 47 inches tall. Stems are erect, and infloresences are branched. This species grows well in USDA hardiness zones 8-11 as a perennial or in zones 3-7 as an annual. They have a long lifespan as cut flowers in fresh arrangements. Various cultivars and varieties are listed and described below:
'Akita'
​To 40 inches tall with 10-12 inch blooms.
'Alfred Grille'
​​Cactus variety with 6-inch blooms. 
'Allan Sparkes'
​Waterlily type with small flowers. To 4.5 feet tall.
'Almand Joy' ('Climax')
​4 foot tall plants with large blooms.
'Alva's Doris'
​To 4 feet tall, with red cactus blooms.
'Alva's Supreme'
Yellow blooms on a 4.5 foot tall plant.​​
'American Dream'
6-8 inch semi-cactus style blooms on a 4-5 foot tall plant.
'Ann Breckenfelder'
​4-inch flowers on a 5.5-foot tall plant.
'Apache'
​​To just under three feet tall.
'April Dawn'
​​4-foot tall plants with 6-inch wide blooms.
'April Heather'
​4-inch collarette blooms that fade to buff.
'Arabian Night'
​​Plants reach 30-40 inches tall.
'Arlequin'
With variegated peach and carmine blooms.​
'Asahi Chohji'
​3-4 inch wide anemone-style flowers.
'Aurora's Kiss'
​​3 inch ball-style flowers on a 4 foot tall plant.
'Autumn Sunburst'
​8-10 inch flowers.
'Babylon Bronze'
​8-10 inch wide blooms.
'Babylon Pink'
​​With 8-10 inch wide blossoms.
'Bednall Beauty'
To 2 feet tall with red flowers.​
'Bishop of Llandaff'
​Red flowers and dark purple-green foliage.
'Blithe Spirit'
​​With 8-10 inch white-tipped red flowers.
'Blyton Softer Gleam'
Rust-orange to gold prolific bloomer.
'Boogie Woogie'
​A powder puff anemone dahlia reaches 3-4 feet tall.
'Bora Bora'
​6-8 inch wide blooms.
'Bridge View Aloha'
​A semi-cactus bloom bright yellow Dahlia with red-orange tips.
'Brookfield Delight'
​To 1.6 feet tall with orange, simple blooms. Great for containers.
'Charlie Dimmock'
​Small waterlily-type Dahlia to just over 4 feet tall.
'Chat Noir'
​To 54 inches tall with 4.5 inch wide flowers.
'Checkers'
​Deep red petals fade to white on this 48 inch tall plant.​
'Chimborazo'
​To 4 feet tall with small open flowers.
'Clair de Lune'
​​A collarette Dahlia with light lemon-yellow flowers.
'Cornel'
​Red flowers to 4 inches across on long, strong stems.
'Cream Alva's'
To 4 feet tall with creamy white blossoms.
'David Howard'
4-5 inch wide flowers with chocolate-brown centers. Dark foliage.
'Don Hill'
A red collarette-type Dahlia with burgundy red flowers.
'Doris Day'
A red, cactus-type Dahlia to about 3.6 feet tall.
'Dovegrove'
To 3 feet tall with red flowers. Good for containers.
'Duet'
Bicolored, 5-6 inch wide blooms on a 35 inch tall plant.
'Dutch Explosion'
Bright white cactus Dahlia with magenta tops. Tall stemmed variety.
'Edinburgh'
Plants to 3 feet tall with white-tipped purple blooms.
'Edwin's Sunset'
To just under 5 feet tall with scarlet red blooms.
'El Paso'
36 to 40 inch tall plants with lilac-purple and yellow flowers.
'Ellen Huston'
Dark-foliaged variety with red blooms.
'Erna Panser'
To 5 feet tall with salmon-peach blooms.
'Eveline'
3-4 foot tall plant with 4-6 inch wide flowers.
'Exotic Dwarf'
​Dwarf plants 1-2 feet tall with small pink flowers.
'Fascination'
With dark green foliage and bright pink flowers. To 3 feet tall.
'Ferncliff Illusion'
To 4 feet tall with 8-10 inch flowers.
'Figurine'
Waterlily-type small flowers on a 5-foot tall plant.
'Finchcocks'
Orange waterlily type Dahlia with divided dark foliage. To 4 feet tall. 
'Franz Kafka'
​A three-foot tall plant that produces pink pom pom blooms.
'Freya's Paso Doble'
4-5 inch wide yellow and white flowers.
'Frigoulet'
​Semi-cactus red and white blooms, 
'Fusion'
To 30 inches tall, with white flowers that have light pink flushing.
'Gallery Art Deco'
Dwarf plant with 5-inch wide flowers.
'Gallery Art Fair'
​To 2 feet tall with white blooms and green foliage.
'Gallery Art Nouveau'
Dwarf plant to 2-2.5 feet tall with pink blooms.
'Gallery La Tour'
Compact Dahlia plants with light pink to buff blossoms.
'Gallery Leonardo'
Dwarf plant with peach-pink blooms.
​'Gallery Pablo'
​4 inch wide blooms on a dwarf plant that reaches just 20 inches tall.
'Gallery Rembrandt'
Compact plants with large pink flowers.
'Gallery Renoir'
​Dwarfed plant with bright pink blooms.
'Gallery Vincent'
​With salmon-orange to peach flowers on a compact grower.
'Garden Show'
With pink, yellow, and white multicolored blooms.
'Gatsby'
A cactus-style Dahlia to 40 inches tall.
'Gerrie Hoek'
Old-fashioned variety with 5-6 inch wide blooms.
'Glorie van Heemstede'
4-5 inch wide blooms in lemon yellow. To 4-5 feet tall.
'Graceland'
'Grenadier'
Bright red flowers pop against dark green foliage.
'Hamari Accord'
6-8 inch wide lemon yellow blooms on a 4 foot tall plant.
'Hamari Bride'
To 4 feet tall with cream-white cactus-style blooms.
'Hamari Gold'
With golden-orange flowers. To 4 feet tall.
'Hamari Rose'
With buff to rose-colored pom-poms on a 4 foot tall plant.
'Happy Days Purple'
Compact plant to 2 feet tall with pink blooms and dark foliage.
'Happy Single First Love'
2 foot tall dark-foliaged plant with peach blooms.
'Happy Single Flame'
Red and yellow single flowers on a 2 foot tall plant with dark foliage.
'Happy Single Princess'
To 2 feet tall. White blooms with pink marks.
'Happy Single Wink'
​Pink blooms on a dark-foliaged plant to 2 feet tall.
'Harzfee'
With peach-pink blooms.
'Henriette'
Cactus-style pale salmon 4-6 inch blooms.
'Hillcrest Candy'
Semi-cactus Dahlia with large blooms to about 4 feet tall.
'Hillcrest Desire'
With bright red cactus-type blooms.
'Hillcrest Regal'
To 4-5 feet tall with red collarette-type blooms.
'Hillcrest Royal'
With magenta cactus blooms on a 4-5 foot tall plant.
'Holland Festival'
A dinnerplate Dahlia to 40 inches tall.
'Honka'
An orchid-type Dahlia with bright yellow 3 inch wide blooms. To 3 feet tall.
'Honka Surprise'
3-inch wide yellow and pink flowers on a 3-foot tall plant.
'Hy Pimento'
To just over 3 feet tall with yellow-gold flowers variegated with dark red.
'Isadora'
4-6 inch cactus blooms on a 3-4 foot tall bushy plant.
'Jamaica'
Red and white blooms on a 36-40 inch tall plant.
'Jan Van Schaffelaar'
Pink pompon Dahlia.
'Jeane Marie'
7-inch wide blooms on a 32-inch tall plant.
'Jodie Wilkinson'
Peach pompon-style flowers.
'Jomanda'
Productive plants produce rusty orange pompon Dahlia flowers.
'Josie Gott'
White pompon Dahlias with pink flushing.
'Karenglen'
A bright scarlet-red pompon-style Dahlia.
'Karma Bon Bini'
To 3-4 feet tall with 4-inch wide blooms.
'Karma Chocolate'
With rich, brown-red chocolate-scented blooms.
'Karma Serena'
To 32-36 inches tall with white double blooms.
'Kate Mountjoy'
White collarette blooms with deep wine-red markings.
'Kelvin Floodlight'
Yellow flowers on a 3-4 foot tall plant.
'Kenora Sunset'
​With yellow flowers that have petals with red tips.
'Kenora Valentine'
Pale red, large-flowered Dahlia.
'Key West'
​Peach to orange Dahlia.
'Kidd's Climax'
4.5 to 5 feet tall, with pink-yellow 8-10 inch wide blooms.​
'Kilburn Rose'
​​
'Knockout'
​18-24 inch tall plant with dark foliage and yellow flowers.
'La Gioconda'
To just under 2.5 feet tall, with red and yellow collarette
'Lakeland Sunset'
This small cactus-type dahlia grows to reach 5 feet tall.
'Le Baron'
To 3-4 feet tall with magenta blooms.
'Lismore Willie'
A classic, butter-yellow Dahlia.
'Magenta Star'
To 3-6.5 feet tall, with dark foliage and simple pink flowers.
'Mainaugold'
Semi-cactus Dahlia with orange-salmon blossoms.
'Marie Schnugg'
3 foot tall plant that produces red orchid-style blooms to over 2 inches wide.
'Mary's Jomanda'
Magenta pompon Dahlias.
'Mayan Pearl'
To just over 2 feet tall with light pink flowers.
'Melody Dora'
To 2 feet tall with pastel peach flowers
'Melody Harmony'
Dahlia with dark foliage and pink to cream-colored blooms.
'Mick's Peppermint'
To just over 3 feet tall with white blooms that have carmine streaks and markings.
'Mistery Day'
​To 35 inches tall with maroon-red and white blooms.
'Moonfire'
​With dark foliage and light yellow and red singular blooms.
'Moor Place'
With small, wine-red to burgundy pompon blooms.
'Mrs. Eileen'
A bright orange dinnerplate Dahlia to 4 feet tall with 7 inch wide blooms.
'Musette'
​With large red and white to buff-colored blooms.
'My-nute Blend'
A variety with small, peach to salmon-colored blooms with yellow blushing.
'Mystic Illusion'
18-36 inch tall plants with dark reddish foliage and yellow flowers with peach hues.
'Nathalie's Wedding'
40-48 inches tall with buff-colored blooms.
'Newaukum Honey'
4-6 inch wide orange to buff-colored blooms.
'Night Butterfly'
4.5-inch red collarette-style Dahlia blooms.
'Nonette'
An heirloom variety to 4-5 feet tall with apricot blooms striped with burgundy.
'Noordwijks Glorie'
​A pinkish-peach dinnerplate dahlia.
'Ocean Bird'
Water lily-type Dahlia blooms in pink on a 39-inch tall plant.
'Osaka'
Buff to yellow-cream large blooms.
'Otto's Thrill'
Classic dinnerplate pink Dahlia with 10 inch blooms.
'Peaches n' Cream'
3.5 to 4.5 foot tall plant with light pink 4-6 inch blossoms.
'Pearl of Heemstede'
A pastel pink water-lily type Dahlia.
'Pianella'
​Watermelon-pink cactus-style Dahlia blooms on a 5 foot tall plant.
'Pink Giraffe'
Semi-cactus style Dahlia with variegated pink and magenta petals.
'Pink Pastelle'
Lavender pink to pink blooms with cream centers.
'Playa Blanca'
With creamy white cactus-style Dahlia blooms on a 36-48 inch tall plant.
'Pooh Swan-Island'
With cheery cherry red and yellow collarette blooms.
'Prefere'
With large, peachy pink blooms.
'Preston Park'
2.3-inch wide red flowers on plants that have dark green foliage.
'Pretty Woman'
​Dwarf cultivar with small magenta flowers and dark foliage. Great for containers.
'Prince Valiant'
With wine-red marked white blossoms.
'Purpinka'
​​Purple-red small anemone flowers on a compact plant to about 10 inches tall.
'Purple Flame'
With purple-magenta blooms that have dark centers.
'Purple Splash'
Pink flowers with purple streaks.
'Red Cap'
Productive plant with pure red classic Dahlia blooms.
'Rothsay Reveller'
Small Dahlia blooms that are wine-red with white tips.
'Ruby Murray'
A compact Dahlia with magenta-pink blooms.
'Ryecroft Jan'
A Pompon-style Dahlia with creamy-white flowers. Plants to 4.5 feet tall.
'Ryecroft Marge'
​4-inch flowers with pink and white petals and yellow centers.​
'Sabrina'
Pink blooms with cream centers.
'Santa Claus Dinner Plate'
8-inch wide blooms on a plant that reaches 3-4 feet tall.
'Scura'
​Red flowers on a plant with dark green-black foliage.
'Seattle'
Yellow and white Dinner plate Dahlia blooms to 8 inches across, plant 36 to 40 inches tall.
'Shep's Memory'
Deep orange dinnerplate Dahlia on a 5 foot tall plant.
'Small World'
A mini-pompon Dahlia with cream-white to pinkish flowers.
'Stacy Rachelle'
Pink blooms with darker pink lines or flushing.
'Strawberry Ice'
Pink flowers with cream to yellowish centers. Plants to 5-5.5 feet tall.
'Sunshine'
Anemone-style Dahlia with yellow petals that have bright orange-red bases. Dark foliage.
'Tahiti Sunrise'
​ Cactus-type Dahlia with yellow and magenta flowers.
'Taratahi Ruby'
Medium to large red waterlily-style Dahlias.
'Teesbrooke Audrey'
Collarette-style Dahlia with lavender-pink outer petals around white inner ones.
'The Phantom'
Anemone-flowering Dahlia with pink outer petals and deep crimson-red central ones.
'Totally Tangerine'
Anemone-style Dahlias with pink-tangerine outer petals and a mass of orange inner ones.
'Trelyn Daisy'
White on white Collarette blooms.
'Trelyn Kiwi'
Very light pink to white Dahlias with green centers.
'Trelyn Rhiannon'
To almost 6 feet tall with over 6-inch wide blooms.
'Twilight Time'
With pink and white water lily style Dahlia blooms.
'Twyning's After Eight'
Dark-foliaged plant to 4 feet tall; white blooms to 3 inches across.
'Twining's Revel'
4 foot tall plant with dark foliage and bright carmine-red flowers.
'Vancouver'
Dinnerplate dahlia with 8-10 inch wide blooms.
'Vulcan'
To 3-4 feet tall with semi-cactus red blooms that fade to reddish-orange.
'Waltzing Mathilda'
Dark-foliaged cultivar with coral blooms.
'Westerton Folly'
Classic, magenta pompon Dahlias.
'Weston Pirate'
Cactus-style Dahlia with cherry red blooms.
'Weston Spanish Dancer'
Compact 3 foot tall Dahlia with 4-inch wide cactus-style blooms.
'Weston Stardust'
To 3 feet tall with yellow and magenta cactus-type Dahlia blossoms.
'White Alva's'
Plant to 48 inches tall with pure white to cream-colored 6-inch wide blooms.
'White Ballet'
With pure white blooms.
'Witteman's Surprise'
Superb pure red Dahlia cultivar.
'Wizard of Oz'
Buff and pink flowers on a 32 inch tall plant. Blooms are 2-3 inch pompons.
'Yankee Doodle Dandy'
​With pink-red and white collarette-style Dahlia flowers.
'Yellow Hammer'
Simple yellow anemone-type blooms on a dark-foliaged plaint.
'Zebrano'
​​
'Zorro'
Velvety-red dinnerplate Dahlia with 11 inch wide blooms.​

​Dahlia tamaulipana (Tree Dahlia)
This species of Dahlia is considered a 'tree type', reaching up to 7 feet tall. These plants are native to Tamaulipas, Mexico. Tree Dahlias are sometimes grown ornamentally in landscapes as specimens and form tall, woody-stemmed plants with green foliage. These plants grow well in USDA hardiness zones 8-11.

​Dahlia tenuicaulis (Tree Dahlia, Everblooming Tree Dahlia)
Flowers on this large species of Dahlia are up to 3 inches wide, and are commonly bubblegum pink. These plants are native to mountainous areas in southern Mexico, and are sometimes available for purchase at nurseries. Everblooming Tree Dahlia does well in USDA hardiness zones 7b-10.

Caring for Dahlia

Dahlias are typically purchased as tubers or as nursery specimens, though they can also be grown from seed. Plant Dahlias in the landscape only when soils have risen to over 60 degrees Fahrenheit after the danger of frost has passed in springtime. Tubers can also be started indoors in pots about a month ahead of planting outdoors to get a head-start on growth in cool-temperature areas. Pick a spot in the garden that receives between 6 and 8 hours of sun each day, and that gets a bit of afternoon shade (especially in warmer climates). These flowers prefer soil that is well-draining and fertile, with a pH of between 6.5 and 7.0.  If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Dahlias can be planted either in-ground or in containers (there are some great dwarf cultivars that thrive in pots). To plant tubers, place them in a 6-8 inch deep hole in the soil with the eyes facing upwards, and then cover the tuber with 2-3 inches of soil. As the stem sprouts, continue to fill in with soil around it until it is equal with the surrounding soil. Some taller varieties may need staking, especially taller Dinnerplate Dahlias, as their blooms are so heavy that stems tend to flop over under their weight; make sure to install any supports at planting time (as opposed to after plants have begun flowering). Do not water Dahlia tubers until they have some above-ground sprouts. Do not mulch around Dahlias, as doing so can cause root and stem rot issues to take hold.

Water new plantings regularly as they establish a strong root system (after the above-ground foliage appears). Mature plants also appreciate moist soil; as a general rule of thumb, water 2 to 3 times each week in hot, dry climates. The best irrigation system for Dahlias is a drip irrigation system; this type of irrigation allows for soil to remain consistently moist but not waterlogged by applying water slowly. After rains, make sure to go outside and shake off water from blooms and foliage. Tubers should begin to bloom about 8 weeks after planting. As flowers fade, remove them (and their stems) from plants to improve their appearance and encourage more blooms to emerge. These plants are heavy feeders; each year in springtime, apply a 2-inch layer of organic compost around the planting area to improve soil structure, drainage, and nutrient load. Continue with compost applications (1 inch around the base of plants) once a month after flowering begins to best support plants while they are in their active growing and blooming stages. Pruning Dahlias is relatively straightforward. As plants are developing and reach about a foot tall, pinch off the top of the main stem. This will stimulate more lateral branching and result in more flowers. At the end of the growing season, cut back plants to just a couple of inches above the ground. This will prepare them for overwintering in the ground. If you are in a cool-winter area, your Dahlias will need to be dug up each year and stored until spring rolls around again. Two weeks after cutting them back, dig up the tubers.

Caring for Dahlia in Containers
Dahlias are best when grown in the ground, but can also be grown as container plants. Choose a container that is at least 16 inches or wider. Ensure that the container has adequate drainage holes in the bottom to allow for excess water to flow away from the root zone. Fill the container with a well-draining potting mix, and apply mulch around the base of the plant to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water regularly to keep soil moderately moist; Dahlias grown in containers will need more frequent irrigation than those grown in the ground. Remove any damaged, diseased, or dead foliage at any time during the growing season, and remove spent flower spikes to neaten up the appearance of plants and encourage reblooms.

Harvesting Dahlia Flowers
Dahlia flowers are best harvested in the morning or evening, when water loss will be at its lowest. Choose flowers that are fully opened. Cut Dahlias will not continue to open. Remove foliage and lower buds to increase the vase life of Dahlia cut flowers, and make sure to keep the water clear of any mold, leaves, or other debris. Dahlias are hollow, and absorb water through the outer layers of the stem; keep the vase filled as much as possible to keep them fresh for a longer amount of time. Store cut Dahlias in a cool place to preserve their color and extend their vase time. It is not recommended to use flower food for Dahlias. Dahlias typically have a vase life of 4-5 days, though some varieties can last for 7-11 days with proper care.

Propagation

Dahlias can be propagated either by using cuttings, division or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting or division method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Dahlias, follow the instructions below:

Propagating Dahlia by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
  2. In early spring, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cuttings will take root. Cut one or more new stems once they reach three or more inches tall where they meet the crown of the tuber. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. Placing a clear plastic bag over the top of the cutting can keep humidity high as it develops. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots. These new plants can bloom in this same season if they are cared for well.
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until it is large enough to make it outdoors. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new Dahlia.

Propagating Dahlia by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
  2. Harvest your seeds. The seed pods will drop all of their ray petals and then turn brownish green when they are mature. Cut off the pod from the plant and allow it to continue to dry in a cool, dark place. Once they are fully dried out, collect the seeds from inside. Make sure to lay seeds out to dry before attempting to store them to discourage mold inside the seed container.
  3. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 10-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  4. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
 
Propagating Dahlia by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, and fresh soil. Division is best done in spring as tubers are putting on new growth for the year, and needs to be done every four to five years regardless of whether you have the goal of propagating the plants for best performance, especially if you are growing your Dahlias in containers. To propagate by division, follow these steps:
  1. Gather your materials. Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the tuber roots. Once you have worked it up out of the ground, lay it out.
  2. Start to tease apart the roots with your fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick tuberous section with growing points, or eyes. Make cuts with a clean, sharp blade.
  3. Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. To re-plant tubers, place them in a 6-8 inch deep hole in the soil with the eyes facing upwards, and then cover the tuber with 2-3 inches of soil. As the stem sprouts, continue to fill in with soil around it until it is equal with the surrounding soil.​
Dahlia seed heads can be collected from plants when they have lost most of their rays.
Dahlia seeds.

Problems and Pests

Dahlias are susceptible to developing issues with the following pests and diseases in the garden:
  • Aphids
  • Spider Mites
  • Slugs
  • Earwigs
  • Leafhoppers
  • Thrips
  • Tarnished Plant Bug
  • Caterpillars
  • Powdery Mildew
  • Verticillium Wilt
  • Gray Mold
  • Aster Yellows
  • Mosaic Viruses
For more information on these pests and diseases, including how to treat and prevent them, consult the following pages:
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Gallery

This informal bed features Clair de Lune lemon-yellow Dahlias, purple Salvia, and orange Coneflower.
This garden features beds of massed Dahlia flowers.
Dahlias are show-stoppers in many gardens, here planted alongside Gladiolus and Aster.
Pollinators prefer collarette or simple anemone-type Dahlias that are open, with easily-accessible pollen.
Dahlias are popular additions to cut flower arrangements, and there are many different colors available.
Cut-flower gardens are not complete with at least one variety of Dahlia.
Container-grown Dahlias can be placed on porches or walkways to add foliage and color to hardscaped areas.
Many dwarfed and compact varieties are available to choose from, and do well in pots.
Deadheading Dahlias cleans up the look of plants and encourages more blooms to pop.

Videos

To to create a beautiful Dahlia potted display.
How to grow Dahlias from tuber.
How to cultivate beautiful Dahlias in your garden.
Check out this alternative to digging up tubers each year..
Quick tips for growing Dahlias.
How to divide Dahlia tubers.

Resources

Expert Tips for Cutting, Conditioning, and Arranging Dahlias
8 Tips for Growing Better Dahlias
Dahlia: Pests and Diseases to Watch Out For
How to Grow Dahlias: The Complete Dahlia Flower Guide
Plant, Grow and Care for Dahlias
Dahlia: Plant Care and Growing Guide
Dividing and Storing Dahlia Tubers
Guide to Growing Dahlias
Wikipedia: List of Dahlia Cultivars
Wikipedia: List of Dahlia Species
Wikipedia: Dahlia
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 278 - 280, Dahlia