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Bulb
Asteraceae
Dahlia ‘Thomas Edison’ (Dahlia ‘Thomas A. Edison’)
Dahlia × pinnata
Thomas Edison produces double decorative flowers measuring 20 cm (8 in), deep purplish-violet with a velvety texture, on an upright clump reaching 100 cm (39 in). The No. 1 Van Noort tuber should be planted 20 cm (8 in) deep, in full sun, in fertile, humus-rich, well-drained soil. Install a support early, pinch the shoots, water deeply at the base, and remove spent flowers until frost. This decorative cultivar is suitable for beds, large pots, and bouquets. In Quebec, lift the tuber in autumn and store it in a cool, dry, frost-free place. Its deep violet florets enrich every arrangement. Its bloom renews generously from July until the first frosts.
- Quantity
- 1 tuber
- Exposure
- Sun
- Life cycle
- Hardy perennial
- Hardiness
- Zone 10
Discover the plant
Common nameDahlia
FamilyAsteraceae
GenusDahlia
TypeBulb
Botanical nameDahlia × pinnata
Reproducible seedsYes
Dahlia ‘Thomas Edison’ (Dahlia ‘Thomas A. Edison’). The 'Thomas Edison' dahlia, also registered as 'Thomas A. Edison', is a classic decorative variety bred in the United States in 1929. Its bushy clump reaches 100 cm (39 in) in height with a spread of 40 cm (16 in) and bears dark green foliage. The fully double flowers can measure up to 20 cm (8 in); their wide, deep purplish-violet florets appear velvety, with slightly paler outer petals. From July until the first frost, flower heads appear one after another above the plant on upright stems. Their royal color creates a powerful focal point in borders, cutting gardens, and large containers.
The generous size is also suitable for spectacular bouquets when stems are harvested when almost open. Plant the No. 1 tuber after the last frost, once the soil has warmed. Lay it 10 cm (4 in) deep, bud side up, in fertile, humus-rich, loose, and freely draining soil. Allow 40 cm (16 in) around the crown, choose full sun, and shelter the plant from strong winds. Install a sturdy stake at planting to support the heavy flower heads. Water sparingly before sprouting, then deeply at the base when the surface is dry. Pinch the shoot when it reaches 20 to 30 cm (8 to 12 in) to encourage branching.
Incorporate mature compost and fertilize moderately, with more potassium when buds appear. Avoid excess nitrogen, which weakens stems and reduces flowering. Pair 'Thomas Edison' with golden rudbeckias, white gauras, light blue sages, and silvery grasses to intensify its deep purple. For a particularly large flower, retain the terminal bud and remove lateral buds; for more bouquets, allow several stems to branch. Harvest flower heads when almost open early in the morning and regularly remove faded flowers. Very double flowers offer little accessible pollen; add single-flowered neighbors for beneficial insects. Monitor for slugs, aphids, spider mites, and earwigs, and maintain good air circulation.
Planting guide
Plant well.Grow beautifully.
Planting depth
10 cm (4 in)
Best planting time
Spring, when the ground is warm
Propagation
Division of tubers, each bearing a viable bud
Growing method
After the last frost, loosen a sunny area to 12 inches (30 cm) and incorporate mature compost. Lay the tuber horizontally 8 inches (20 cm) deep, bud side up, then keep 16 inches (40 cm) around the crown. Backfill without compacting and only water if the soil becomes dry before emergence. Pinch the shoot 8 to 12 inches (20 to 30 cm) above a pair of leaves. Immediately install a sturdy stake. When growth accelerates, water deeply at the base and fertilize sparingly, favoring potassium for the buds. Tie the stems with soft ties, harvest flowers when almost open, and remove spent flower heads. After frost, cut the stems, lift the tuber, let its surface dry, and store it in a cool, dry, frost-free place. The deep purplish-violet contrast with velvety texture remains sharper when the plant receives at least six hours of direct sun and regular feeding without excessive nitrogen. An early-installed stake supports the 8-inch (20 cm) flower heads after rain without compressing the stems or damaging active roots. Remove faded flowers before seed formation so that the clump directs its energy towards new buds until the first frost.
Soil and care
The right care,at the right time.
Soil pH
Slightly acidic to neutral
Minimum temperature
5 °C (41 °F)
Care level
Moderate
Watering
Water regularly to keep the soil evenly moist without overwatering. Reduce watering before autumn tuber lifting. Before watering, check the moisture beneath the surface with your finger rather than following a fixed schedule. Recent rain, wind, and container growing can quickly alter needs. Direct water to the soil at the base of the plant and allow any excess to drain freely.
Soil type
Opt for humus-rich soil that retains moisture while allowing excess water to drain away. Check the drainage after rain: water should be able to leave the root zone. Work the soil when it is dry to avoid compacting it. Adjust amendments to its actual texture. In containers, use appropriate potting soil and a pot with drainage holes. Keep these openings clear and avoid any water accumulation in the saucer.
Fertilization
Incorporate mature compost before planting. At the start, use a balanced formula low to moderate in nitrogen, then favor more potassium when buds appear. Follow the recommended dosage and then water. Too much nitrogen produces tender stems and fewer flowers. The deep purplish-violet contrast with the velvety texture remains sharper when the plant receives at least six hours of direct sun and regular feeding without excess nitrogen.
Seasonal care
In spring, inspect the tuber, remove only rotten tissue, and plant after the last frost in warmed soil. Install support immediately. Until emergence, avoid repeated watering. In early summer, pinch the shoot at 20 or 30 cm (8 to 12 in), tie new stems, and keep the soil moist without saturation. As soon as buds appear, fertilize moderately with more potassium. In summer, water deeply at the base during dry periods, harvest nearly open flowers, and continuously remove faded flower heads. Monitor for slugs, aphids, earwigs, spider mites, and gray mold. After the first frost, cut the stems, gently lift the tuber, let its surface dry, label it Thomas Edison, and store it in a cool, dry, dark, and frost-free place. Check it monthly during winter. The deep purplish-violet contrast with a velvety texture remains sharper when the plant receives at least six hours of direct sun and regular feeding without excess nitrogen. An early-installed stake supports the 20 cm (8 in) flower heads after rain without compressing stems or damaging active roots. Remove spent flowers before seed formation so that the clump directs its energy towards new buds until the first frost. Always water slowly at the base, then let the top layer breathe to maintain a balance between moisture, oxygen, and drainage. The deep purplish-violet shades with a velvety texture pair particularly well with blue, white, and purple perennials and light grasses.
Container growing
A garden,within reach.
Recommended pot size
Container with a capacity of 40 to 50 L, deep and very stable
Container gardening requires you to plan for the necessary root volume and the plant's final height. Choose a stable pot with drainage holes and a substrate suitable for planting. Leave enough space to respect the recommended depth and spacing, rather than crowding plants to immediately fill the pot. Place the container in the indicated exposure and regularly check the moisture, especially in hot or windy weather. A pot is more exposed to temperature variations than a plant in the ground. Therefore, plan for a wintering location from the start that is compatible with the plant's needs and your region's climate. Plant in spring when all risk of frost has passed and the soil has warmed sufficiently. Choose a sunny spot, sheltered from strong winds, in fertile, well-drained soil. Arrange the tuberous roots with their crown and buds facing upwards, without breaking the fragile attachments. Install a stake at planting if support will be necessary, to avoid damaging the roots later. Water sparingly at the start, then adapt watering to foliage growth. Consistently soggy soil around the tubers should be avoided, especially before the first shoots appear. Plan to bring the storage organs indoors, away from frost, for the Quebec winter.
Bloom and dimensions
Its place,in your garden.
Mature height
100 cm (40 in)
Width / spread
40 cm (16 in.)
Flower color
Deep and velvety purple
Foliage color
Green
Foliage type
Obsolete
Growth rate
Quick
Bloom period
The large ornamental flowers have wide, deep purple, velvety petals. The fully double flowers can measure up to 8 in. (20 cm); their large, deep purplish-violet florets appear velvety, with slightly paler outer petals. Incorporate mature compost and fertilize moderately, with more potassium as buds appear. For a particularly large flower, retain the terminal bud and remove the lateral buds; for more bouquets, allow several stems to branch out. Harvest almost open flower heads early in the morning and regularly remove faded flowers.
Harvest
July to October. Pick the flowers when they are fully open for the best vase life.
Garden associations
In goodcompany.
Companion plants
To accompany 'Thomas Edison' dahlia, you can consider cosmos, zinnias, or ornamental salvias. Choose companion varieties based on their height, flowering period, and the colors you wish to combine. Most importantly, ensure that their sun exposure and water needs are suitable for the same location. Maintain enough distance so that leaves do not obscure young shoots and to allow easy access to each plant during maintenance. These pairings are intended to compose the garden's aesthetic; they do not guarantee protection against pests or diseases. Adjust the arrangement after observing one growing season.
Frequently asked questions
Your questions,answered.
When to plant the dahlia Thomas Edison?
Plant the tuber after the last frost, when the soil has warmed up and is no longer saturated. Plant it 20 cm (8 in) deep, bud facing upwards, in fertile, humus-rich, well-drained soil. Leave 40 cm (16 in) around the crown and install a support immediately. In a cold region, start it in a pot four to six weeks earlier, then gradually acclimate the shoot before planting it out. Water very sparingly before emergence to prevent rot, then increase watering when the roots and stems are active. Full sun develops strong stems and intensifies the purple-red and black contrast.
What colors are Thomas Edison's flowers?
Thomas Edison can produce flower heads up to 8 inches (20 cm) across when the plant receives full sun, fertile soil, deep watering, and balanced nutrition. To focus energy into one flower, keep the terminal bud on a stem and gently remove the side buds. Install a sturdy stake before growth and loosely tie the stem. This technique reduces the total number of flowers; therefore, allow several other stems to branch out normally if you also want to harvest bouquets throughout the season. Protect large flower heads from strong winds and prolonged rain. Check each tie after summer storms.
How to support and help Thomas Edison flourish?
Install a sturdy stake at planting to avoid damaging roots later. Tie the stems with flexible ties as they grow. Pinch off the young shoot when it reaches 20 to 30 cm (8 to 12 in) to encourage multiple branches. Water deeply at the base when the surface is dry, then allow excess water to drain. Incorporate mature compost initially and then use a moderate fertilizer, richer in potassium once buds begin to form. Avoid excess nitrogen, which produces tender stems and a lot of foliage. Regularly remove spent flowers so that energy is directed to the next buds until frost.
Can Thomas Edison grow in a large pot?
Yes, choose a stable container that is 40 to 50 L, deep, well-drained, and filled with rich but aerated potting mix. Plant a single tuber 20 cm (8 in) deep and insert the support before the roots develop. Place the pot in full sun, protected from gusts of wind. Water sparingly before sprouting, then abundantly once the top layer dries, without leaving any water in the saucer. Apply a moderate liquid fertilizer, richer in potassium as soon as buds appear. Turn the container every week, pinch back new growth, and remove faded flowers to maintain a balanced shape and generous blooms.
How to winterize Thomas Edison in Quebec?
After the first frost blackens the foliage, cut back the stems, leaving a short stub. Lift the tuber with a fork, working far enough away not to damage it. Gently remove excess soil, allow the surface to dry in a ventilated area, and clearly label it Thomas Edison. Store it in a cool, dry, dark, and frost-free place, in a slightly insulating material that limits desiccation without retaining water. Inspect it monthly. Remove only parts showing active rot and increase ventilation if condensation appears. Wait until after the last spring frost and for the soil to warm up before replanting.
Wildlife and pets
Life,around your plants.
Supporting wildlife
Very double flowers limit access to pollen and nectar. Thomas Edison contributes mainly through its ornamental value. To feed bees and butterflies, plant salvias, verbenas, echinaceas, or other single flowers rich in resources nearby. The deep purplish-violet contrast with its velvety texture remains sharper when the plant receives at least six hours of direct sunlight and regular feeding without excess nitrogen.
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