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Dormant tuber
Asteraceae
Giant yellow Dinnerplate dahlia
Giant ‘Kelvin Floodlight’ dahlia
Dahlia ‘Kelvin Floodlight’
Product code : VAN-327-412-25
Kelvin Floodlight produces very large, fully double decorative flowers in uniform bright yellow. Its No1 tuber forms an upright branching clump approximately 90 cm tall and 50 cm wide, ideal for luminous borders, large containers, and cutting gardens. Plant it 10 cm deep in full sun and fertile, humus-rich, moist, freely drained soil. Early support, deep watering at soil level, moderate potassium-rich feeding, and removal of faded flowers sustain bloom from summer until frost. In cold Canadian climates, lift the tuber after the first frost and store it somewhere cool, dry, dark, and frost-free. Regular cutting encourages additional buds through late summer..
- Quantity
- 1 tuber
- Exposure
- Full sun
- Life cycle
- Annual under Quebec conditions
- Hardiness
- Zone 8; lift the tuber in colder regions
Discover the plant
Common nameGiant Kelvin Floodlight dahlia
FamilyAsteraceae
GenusDahlia
SpeciesGarden hybrid of Dinnerplate type
CultivarKelvin Floodlight
TypeDormant tuber
Botanical nameDahlia ‘Kelvin Floodlight’
Giant ‘Kelvin Floodlight’ dahlia (Dahlia ‘Kelvin Floodlight’) forms an upright, branching clump approximately 90 cm tall and 50 cm wide. Very large, fully double decorative flowers display a uniform bright yellow that appears to capture light. Generous flowerheads rise above dark green foliage and become powerful focal points in borders and exhibition arrangements. Van Noort’s No1 tuber flowers through summer and continues producing until the first frost when faded blooms are removed. Its Dinnerplate silhouette suits sunny borders, large stable containers, and cutting gardens that need clear luminous colour. The accepted RHS profile confirms its upright clump-forming habit, very large yellow flowers, and value for cutting or exhibiting.
Plant the tuber in spring after the final frost once the soil is warm and drained. Lay it 10 cm deep with the bud facing upward in fertile, humus-rich, moist, freely drained soil. Leave approximately 50 cm around the crown and install sturdy support immediately. Water sparingly before emergence, then deeply at soil level whenever the surface begins to dry. Pinch the young shoot between 20 and 30 cm to encourage several branches. Incorporate mature compost before planting and apply moderate fertilizer afterward, shifting toward higher potassium as buds develop. Avoid standing water, excessive nitrogen, and repeated irrigation over the large flowerheads. Maintain open airflow during humid summer weather.
Place Kelvin Floodlight in the middle or rear of a border where bright-yellow flowers can combine with blue salvias, violet verbenas, chocolate cosmos, and flexible grasses. Harvest stems when flowers are nearly open and remove faded flowerheads regularly to extend flowering. Highly double blooms offer little pollen access, so include nearby single flowers for useful insects. Watch for slugs, aphids, earwigs, and spider mites, then maintain generous airflow. In cold Canadian climates, lift the tuber after the first frost, let its surface dry, label it, and store it in darkness somewhere cool, dry, and frost-free until the following spring. Inspect stored material monthly and remove only actively rotting tissue.
Planting guide
Plant well.Grow beautifully.
Planting depth
10 cm (4 in)
Spacing / density
50 cm (20 in) between plants
Best planting time
May to early June once soil is warm
Propagation
Division of a tuber carrying a viable bud
Growing method
After the final frost, loosen sunny soil to 30 cm and incorporate mature compost. Lay the tuber horizontally 10 cm deep with its bud upward, keeping 50 cm around the clump. Close without compacting and water sparingly before emergence to prevent rot. When shoots reach 20 to 30 cm, pinch above a leaf pair to encourage branching. Install a discreet stake or ring immediately. Water deeply at the base whenever the surface dries and apply fertilizer moderate in nitrogen and richer in potassium from bud formation. Tie stems with soft material. Remove faded flowers until frost. Once foliage blackens, cut, lift, dry, and store the tuber away from frost. Kelvin Floodlight is a giant Dinnerplate dahlia with large double luminous yellow flowers. Broad gently curved petals create full, balanced flowerheads with refined texture. The upright clump reaches about one metre and benefits from discreet staking in windy places. Full sun and fertile humus-rich fresh drained soil support sturdy stems. Feeding moderate in nitrogen and richer in potassium accompanies bud formation. Pinching branches young shoots and removing faded flowerheads extends flowering. In Quebec, the tuber must be lifted after frost and stored somewhere cool and frost-free.
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
Before emergence, water only when soil becomes distinctly dry. Once stems establish, apply water deeply at the base whenever the surface begins drying, especially during bud development and heat. Let drainage work between applications. Avoid wetting double flowers and foliage in the evening because prolonged moisture favours spotting and grey mould. Kelvin Floodlight is a giant Dinnerplate dahlia with large double luminous yellow flowers.
Soil type
Prepare fertile, humus-rich, loose, freely drained loam retaining even freshness during growth. Mature compost improves structure and supplies gentle reserves. On heavy soil, raise the planting slightly and incorporate coarse mineral material. Avoid hollows where water stands around the tuber, constantly wet substrates, and very dry ground that weakens stems and buds. Kelvin Floodlight is a giant Dinnerplate dahlia with large double luminous yellow flowers.
Fertilization
Incorporate mature compost before planting. From active growth, use balanced fertilizer low to moderate in nitrogen, then favour a potassium-richer formula as buds form. Follow labelled rates and water afterward. Excess nitrogen produces soft stems, abundant leaves, and fewer flowers. Stop feeding several weeks before autumn lifting. Kelvin Floodlight is a giant Dinnerplate dahlia with large double luminous yellow flowers. Broad gently curved petals create full, balanced flowerheads with refined texture.
Moisture
Maintain even soil moisture without saturation during active growth. Large double flowers become heavy after rain; good air circulation, 50 cm spacing, and support reduce breakage and slow drying. Never let thick mulch touch the crown. During storage, keep a cool dry atmosphere that prevents both extreme shrivelling and rot. Kelvin Floodlight is a giant Dinnerplate dahlia with large double luminous yellow flowers.
Seasonal care
In spring, inspect the tuber, prepare soil, plant after frost, and install support before stems become fragile. Pinch young shoots to branch the clump. In summer, water deeply, tie with soft material, feed moderately, and remove faded flowers regularly. Harvest stems early in the morning using clean tools. Monitor slugs, aphids, earwigs, spider mites, and mould without needlessly treating neighbouring flowers. In autumn, wait until frost blackens foliage, cut stems to 10 or 25 cm, lift the tuber without injury, and let its surface dry. Label Kelvin Floodlight clearly. In winter, store it somewhere cool, dry, dark, and frost-free. Inspect monthly, remove soft tissue, and prevent both condensation and complete desiccation. Kelvin Floodlight is a giant Dinnerplate dahlia with large double luminous yellow flowers. Broad gently curved petals create full, balanced flowerheads with refined texture. The upright clump reaches about one metre and benefits from discreet staking in windy places. Full sun and fertile humus-rich fresh drained soil support sturdy stems. Feeding moderate in nitrogen and richer in potassium accompanies bud formation. Pinching branches young shoots and removing faded flowerheads extends flowering. In Quebec, the tuber must be lifted after frost and stored somewhere cool and frost-free. Double flowers suit arrangements and borders but provide little food for pollinators. Water deeply at the base when the surface dries without saturating the crown.
Container growing
A garden,within reach.
Recommended pot size
At least 45 cm wide and deep
Use a stable container at least 45 cm wide and deep with numerous holes. Fill it with rich potting mix amended with compost and drainage material. Set one tuber 10 cm below the surface and immediately install a central stake or discreet cage. Keep the pot in full sun protected from strong wind. Water deeply whenever the upper centimetres dry and always empty the saucer. Feed moderately during growth, then emphasize potassium from bud formation. Pinch young shoots and remove faded flowers. Rotate the container regularly for balanced growth. After the first frost, cut stems, let the mix dry slightly, and remove the tuber for cool dry frost-free storage until spring. Kelvin Floodlight is a giant Dinnerplate dahlia with large double luminous yellow flowers. Broad gently curved petals create full, balanced flowerheads with refined texture. The upright clump reaches about one metre and benefits from discreet staking in windy places. Full sun and fertile humus-rich fresh drained soil support sturdy stems. Feeding moderate in nitrogen and richer in potassium accompanies bud formation. Pinching branches young shoots and removing faded flowerheads extends flowering. In Quebec, the tuber must be lifted after frost and stored somewhere cool and frost-free.
Bloom and dimensions
Its place,in your garden.
Mature height
About 90 cm (35 in)
Width / spread
About 50 cm (20 in)
Flower color
Uniform bright yellow
Foliage color
Green
Foliage type
Deciduous after frost
Growth rate
Fast
Growth habit
Tall upright clump
Bloom period
Fully double Kelvin Floodlight flowers are very large and repeat from midsummer until the first frost. Broad luminous yellow petals form full, balanced, luminous Dinnerplate blooms. Cut faded flowerheads above a leaf pair to renew buds. Support and good airflow protect this delicate texture after rainfall. Kelvin Floodlight is a giant Dinnerplate dahlia with large double luminous yellow flowers. This attention preserves vigour and the quality of its large luminous yellow flowers.
Harvest
July to October. Pick the flowers early in the morning for better vase life. Regularly remove withered flowers to prolong blooming.
Garden associations
In goodcompany.
Companion plants
Pair Kelvin Floodlight with blue salvias, purple verbenas, yellow gauras, chocolate cosmos, sweet alyssum, and bronze grasses sharing sun and drained soil. Airy silhouettes and simple flowers highlight giant Dinnerplate flowerheads while providing insects with more accessible resources. Keep 50 cm around the tuber and avoid highly aggressive roots or plants requiring constantly dry ground. Kelvin Floodlight is a giant Dinnerplate dahlia with large double luminous yellow flowers. Broad gently curved petals create full, balanced flowerheads with refined texture. This attention preserves vigour and the quality of its large luminous yellow flowers.
Frequently asked questions
Your questions,answered.
When should Kelvin Floodlight dahlia be planted?
Plant Kelvin Floodlight in spring after the final frost when soil has warmed and no longer remains saturated. Lay the tuber horizontally 10 cm deep with its bud upward, keeping 50 cm clear around the crown. In cold regions, starting it indoors in a pot four to six weeks earlier advances growth, but acclimate the plant gradually before moving it outside. Water very sparingly before emergence to prevent rot, then increase moisture as shoots and roots become active. Install support immediately to protect future giant blooms from wind and rain. This careful practice supports consistent flowering and protects the delicate fringed texture of every bloom.
How large does Kelvin Floodlight grow?
Kelvin Floodlight reaches approximately 90 cm tall and 50 cm wide according to Van Noort. Its upright branching habit needs sturdy support installed at planting, especially once the very large double flowerheads become heavy after rain. Leave approximately 50 cm around the crown to maintain airflow and simplify harvesting. Pinching the young shoot at 20 to 30 cm encourages several branches, producing a more balanced outline and additional flowering stems. Avoid excessive nitrogen, however, because it lengthens stems and makes them softer. Check ties after storms without constricting new growth, and keep the base open so irrigation drains freely around the tuber..
How can very large flowers be produced?
The RHS notes that Kelvin Floodlight may reach approximately 25 cm when the plant is disbudded. To concentrate its energy, retain the central bud on a strong stem and gently remove the two side buds while they are still small. Do not use this technique on every branch because it reduces the total flower count. Provide full sun, rich drained soil, deep watering at the base, and moderate fertilizer richer in potassium. Support the selected stem firmly and protect its bloom from strong wind. Without disbudding, flowers remain abundant and naturally very large. This careful practice supports consistent flowering and protects the delicate fringed texture of every bloom.
Can Kelvin Floodlight grow in a container?
Yes. Choose a stable container at least 45 cm wide and deep with large drainage holes. Fill it with fertile airy potting soil, plant the tuber 10 cm deep, and immediately install support. Keep the pot in full sun with shelter from strong gusts. Water deeply when the upper few centimetres dry and always empty the saucer. Feed moderately with additional potassium from bud formation, pinch the shoot, and remove faded flowers. Rotate the container for balanced growth and inspect ties after rain. Before frost, lift the tuber and store it somewhere cool, dry, dark, and frost-free until the following spring..
How should the tuber be overwintered in Canada?
After the first frost blackens foliage, cut stems to 10 or 15 cm. Lift widely around the crown with a fork to avoid injuring tuberous roots, gently remove loose soil, and let the surface dry in a sheltered place. Store the labelled tuber in lightly insulating material somewhere cool, dry, dark, and frost-free. Inspect it monthly, remove any soft section with a clean tool, and increase ventilation if condensation appears. Replant only after frost risk has passed and the soil has warmed. This careful practice supports consistent flowering and protects the delicate fringed texture of every bloom. This careful practice supports consistent flowering and protects the delicate fringed texture of every bloom.
Wildlife and pets
Life,around your plants.
Supporting wildlife
Fully double Kelvin Floodlight flowers hide nearly all of their disc and therefore offer little accessible pollen or nectar. Their value is mainly ornamental. Support wildlife by pairing this dahlia with salvias, sweet alyssum, verbenas, and other simple flowers, avoiding insecticides, providing shallow clean water, and maintaining several flowering periods in the border. Kelvin Floodlight is a giant Dinnerplate dahlia with large double luminous yellow flowers.
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