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Bulb
Asteraceae
Dahlia ‘Topmix Yellow’ (Dahlia)
Dahlia pinnata
Topmix Yellow produces single, open flowers measuring 5 cm (2 in), bright yellow with purple-yellow tips, on an upright clump of 35 cm (14 in). The No1 Van Noort tuber should be planted 10 cm (4 in) deep, in full sun, in fertile, humiferous, and well-drained soil. Install a support early, pinch the shoots, water deeply at the base, and remove faded flowers until frost. This simple cultivar is suitable for beds, large pots, and bouquets. In Quebec, lift the tuber in autumn and store it in a cool, dry, and frost-free place. Its dark yellow florets enhance any arrangement. Its blooms generously renew from July until the first frosts. compact yellow dahlia border dahlia full sun dahlia Van Noort Quebec
- Quantity
- 1 tuber
- Exposure
- Sun
- Life cycle
- Hardy perennial
- Hardiness
- Zone 10
Discover the plant
Common nameDahlia 'Topmix Yellow'
FamilyAsteraceae
GenusDahlia
TypeBulb
Botanical nameDahlia pinnata
Reproducible seedsYes
Dahlia ‘Topmix Yellow’ (Dahlia) forms a compact, upright clump about 50 cm (20 in) tall and 50 cm (20 in) wide. Its numerous bright yellow single flowers surround a well-exposed golden yellow central disc. The luminous flower heads stand out clearly against the green foliage and branched stems, providing a sunny presence without obscuring neighboring plants. Van Noort’s No1 tuber blooms during the summer and continues to produce until the first frost when spent flowers are removed. Its Mignon size is suitable for borders, small beds, patios and containers, while its open centers remain accessible to bees, hoverflies and butterflies.
Plant the tuber after the last frost, when the soil has warmed up, in a sheltered location receiving full sun. Lay it 10 cm (4 in) deep, bud side up, in fertile, humus-rich, cool and freely draining soil. Leave 50 cm (20 in) around the crown. Water sparingly before sprouting, then deeply at the base when the surface dries. Pinch the young shoot at about 20 cm (8 in) to encourage dense branching. Incorporate mature compost before planting and then apply moderate fertilization, richer in potassium as buds appear. Avoid excess nitrogen, stagnant water and repeated watering on the foliage.
Place Topmix Yellow at the front of a border or in a stable pot near a seating area to enjoy its bright, simple flowers. Combine it with blue sages, purple verbenas, white alyssum, purple calibrachoas and fine grasses to enhance the contrast. The open centers provide direct access to pollen and nectar; therefore, avoid pesticides on the flower heads. Regularly remove spent flowers, monitor for slugs, aphids and spider mites, and maintain generous air circulation. In Quebec, after the first frost, lift the tuber, let its surface dry, label it and store it in a dark, cool, dry and frost-free place until spring.
Sowing guide
It all startswith a seed.
Sowing depth
10 cm (4 in)
Sowing period
Spring
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 4 inches (10 cm) deep, bud side up, then keep 12 inches (30 cm) around the crown clear. 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 moderately, favoring potassium for the buds. Tie the stems with soft ties, harvest flowers when almost open, and remove faded 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 bright yellow contrast with purplish-yellow tips remains sharper when the plant receives at least six hours of direct sunlight and regular feeding without excess nitrogen. A stake installed early supports the 2-inch (5 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
Easy
Watering
Water regularly to keep the soil evenly moist without overwatering. Reduce watering before autumn tuber lifting. Water sparingly before emergence, then deeply at the base when the surface dries. Avoid excess nitrogen, standing water, and repeated watering on the foliage. In Quebec, after the first frost, lift the tuber, let its surface dry, label it, and store it in a cool, dry, dark, and frost-free place until spring.
Soil type
Prioritize a humus-rich soil that retains moisture while allowing excess water to drain. Check drainage after rain: water must be able to leave the root zone. Work the soil when it is dry enough to avoid compacting it. Adapt amendments to its actual texture. For container plants, use an appropriate potting mix and a pot with drainage holes. Keep these openings clear and avoid any accumulation of water in the saucer.
Fertilization
Incorporate mature compost before planting. At the start, use a balanced formula with low to moderate nitrogen, then favor more potassium when buds appear. Follow the recommended dosage and water afterwards. Too much nitrogen produces tender stems and fewer flowers. The bright yellow contrast with purplish-yellow tips remains sharper when the plant receives at least six hours of direct sunlight 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 spent blooms. 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 Topmix Yellow, and store it in a dark, cool, dry, and frost-free place. Check it monthly during winter. The bright yellow contrast with purplish-yellow tips remains sharper when the plant receives at least six hours of direct sun and regular feeding without excess nitrogen. A stake installed early supports the 5 cm (2 in) flower heads after rain without compressing the 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 bright yellow shades with purplish-yellow tips pair particularly well with blue, white, yellow perennials and light grasses.
Container growing
A garden,within reach.
Recommended pot size
12 to 15 L, 30 cm (12 in.) diameter
Container gardening requires planning 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 fill the pot immediately. 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 planting in the ground. Therefore, plan from the outset for a wintering location 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 and well-drained soil. Arrange the tuberous roots with their crown and buds facing upwards, without breaking the fragile attachments. Install a stake at the time of planting if support will be needed, to avoid injuring the roots later. Water sparingly at the start, then adapt the watering to the foliage growth. Constantly soggy soil around the tubers should be avoided, especially before the appearance of the first shoots. Plan to bring the storage organs indoors, out of frost, for the Quebec winter.
Bloom and dimensions
Its place,in your garden.
Mature height
30 to 40 cm (12 to 16 in.)
Width / spread
25 to 30 cm (10 to 12 in)
Flower color
True yellow with a golden yellow central disc
Foliage color
Green
Foliage type
Lapsed
Growth rate
Quick
Bloom period
The simple, bright yellow flowers with golden centers continuously renew themselves until the first frosts when regularly deadheaded. Van Noort's No. 1 tuber flowers during the summer and continues to produce until the first frost when spent flowers are removed. Incorporate mature compost before planting, then provide moderate fertilization, richer in potassium, once buds appear. Avoid excess nitrogen, standing water, and repeated watering on the foliage. Place Topmix Yellow at the front of a border or in a stable pot near a seating area to enjoy its luminous, simple flowers.
Harvest
June to October. Pick fully opened flowers for small bouquets or allow them to fade naturally before removing them.
Garden associations
In goodcompany.
Companion plants
To accompany Dahlia ‘Topmix Yellow’, you might consider cosmos, zinnias, or ornamental salvias. Choose neighboring varieties based on their height, flowering period, and the colors you wish to combine. Above all, ensure their sun exposure and water needs are suitable for the same location. Maintain enough distance so that leaves don't obscure young shoots and to allow easy access to each plant during maintenance. These pairings are for garden aesthetics; 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 Dahlia Topmix Yellow?
Plant the tuber after the last frost, once the soil has warmed and is no longer saturated. Lay it 10 cm (4 in.) deep, bud facing upwards, in fertile, humus-rich, well-drained soil. Leave 30 cm (12 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 little before emergence to prevent rot, then increase watering once the roots and stems are active. Full sun develops strong stems and intensifies the purple-yellow and black contrast.
What colors do Topmix Yellow flowers have?
Topmix Yellow is more useful to pollinators than fully double dahlias because its central disk remains open. Bees, hoverflies, and butterflies can directly access pollen and nectar when the flowers are fresh. Place the pot or border in the sun, avoid spraying pesticides on the flower heads, and leave several flowers open during the day. Then remove faded flowers to encourage new bud formation. Combine with alyssum, salvias, verbenas, or other single flowers to provide complementary resources before and after peak dahlia bloom times. In a small garden, this succession also maintains the activity of beneficial insects. A shallow, frequently refilled saucer of water usefully completes the welcome during hot days. The exposed center finally allows observation of visits without handling the flowers or disturbing the insects.
How to support and make Topmix Yellow flourish?
Install a sturdy stake at planting to avoid damaging the roots later. Tie the stems with soft ties as they grow. Pinch the young shoot at 20 to 30 cm (8 to 12 in) to encourage multiple branches. Water deeply at the base when the surface dries, then allow excess water to drain away. Incorporate mature compost initially and then use a moderate fertilizer, richer in potassium once buds form. Avoid excess nitrogen, which produces tender stems and a lot of foliage. Regularly remove faded flowers so that energy is directed to subsequent buds until frost.
Can Topmix Yellow grow in a large pot?
Yes, choose a stable container of 12 to 15 L, deep, well-drained, and filled with rich but aerated potting soil. Plant a single tuber 10 cm (4 in) deep and insert the support before the roots develop. Place the pot in full sun, protected from gusts. Water sparingly before sprouting, then abundantly when the top layer dries, without leaving water in the saucer. Apply moderate liquid fertilization, richer in potassium as soon as buds appear. Turn the container weekly, pinch back new shoots, and remove faded flowers to maintain a balanced shape and generous blooms.
How to overwinter Topmix Yellow 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 to avoid damaging it. Gently remove excess soil, allow the surface to dry in a well-ventilated area, and clearly label it Topmix Yellow. Store it in the dark, in a cool, dry, 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 it.
Wildlife and pets
Life,around your plants.
Supporting wildlife
Simple flowers with open discs give bees, hoverflies, and butterflies direct access to pollen and nectar. Leave several flower heads open during the day, avoid pesticides on the flowers, and add alyssum, sage, or verbena to extend resources around the pot or border.
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