Dinnerplate Dahlias: How to Grow Giant Dahlia Flowers
Dinnerplate Dahlias: How to Grow Large Dahlia Flowers
Dinnerplate dahlias are some of the most dramatic flowers you can grow. Known for their large, showy blooms, they create instant impact in the garden and make impressive feature flowers in arrangements.
If you want big summer flowers, dinnerplate dahlias are worth growing. They do need a little more space, support and care than smaller dahlias, but the results can be spectacular.
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What are dinnerplate dahlias?
Dinnerplate dahlias are dahlias that produce very large flowers. The blooms are often much bigger than standard dahlia flowers and can become the main feature in a garden bed or bouquet.
They are popular because of their size, colour and dramatic appearance. One large bloom can make a strong statement on its own.
Are dinnerplate dahlias difficult to grow?
Dinnerplate dahlias are not necessarily difficult, but they do need the right conditions. Because the plants and flowers are large, they need enough space, good soil, consistent moisture and strong support.
If they are planted too close together, grown in poor soil or left unstaked, they may not perform at their best.
When to plant dinnerplate dahlias in South Africa
Plant dinnerplate dahlia tubers in spring, once the risk of frost has passed and the soil has warmed up.
- Western Cape: late August to October, depending on the season.
- Colder inland areas: September to November, once frost danger has passed.
- Warmer coastal areas: planting may be possible slightly earlier.
Avoid planting into cold, wet soil, as this can increase the risk of tuber rot.
Where to plant dinnerplate dahlias
Dinnerplate dahlias need full sun to flower well. Choose a position with at least 6 hours of sun per day. Because the plants can become tall and heavy, a sheltered spot is helpful.
- Sun: Full sun is best.
- Soil: Fertile but well-drained soil.
- Wind: Choose a protected position if possible.
- Space: Give plants enough room to grow.
How far apart to plant dinnerplate dahlias
Dinnerplate dahlias need more space than compact varieties. Plant them around 60–90 cm apart. This gives the plants room to develop and improves airflow around the foliage.
Good spacing also makes it easier to stake, tie and cut flowers later in the season.
How deep to plant dinnerplate dahlia tubers
Plant the tuber shallowly, with the crown or eye just below the soil surface. Cover with about 3–5 cm of soil. Do not bury the tuber too deep, especially early in the season.
If the tuber already has a shoot, take care not to damage it during planting.
Staking is essential
Dinnerplate dahlias should be staked at planting time. The flowers can become heavy, especially after rain or in windy weather. If the plant is not supported, stems may bend or break.
Place a strong stake next to the tuber when planting. As the plant grows, tie the main stems gently to the stake.
Watering dinnerplate dahlias
After planting, water lightly and avoid keeping the soil too wet before shoots appear. Once the plant is actively growing, keep the soil evenly moist.
Large dahlias need consistent moisture to support strong stems and big flowers. During hot, dry or windy weather, they may need more regular watering.
Feeding for large dahlia blooms
Dinnerplate dahlias benefit from feeding once they are established. Use a balanced fertiliser, but avoid too much nitrogen. Excess nitrogen can produce large leafy plants with fewer flowers.
A steady, moderate feeding programme is better than overfeeding.
Should you pinch dinnerplate dahlias?
Yes. Pinching can help create a stronger, bushier plant with more flowering stems. When the plant is about 30 cm tall, pinch out the growing tip to encourage side shoots.
This may delay the first flower slightly, but it often improves the overall plant shape and flower production.
How to get bigger dahlia flowers
If you want fewer but larger blooms, you can remove some side buds and allow the plant to put more energy into selected flowers. This is called disbudding.
For general garden display, you do not have to disbud. But if your goal is very large show blooms, disbudding can help.
Deadheading for more flowers
Remove faded flowers regularly. This encourages the plant to keep producing new blooms instead of putting energy into seed production.
When deadheading, cut the spent flower stem back to a leaf joint rather than just removing the flower head.
Can dinnerplate dahlias grow in pots?
Yes, but they need large containers. Use a strong pot of at least 40–50 cm wide, with excellent drainage. Add a sturdy stake at planting time.
Potted dinnerplate dahlias need careful watering because large plants can dry out quickly in containers.
Are dinnerplate dahlias good cut flowers?
Dinnerplate dahlias make stunning cut flowers, but they are often used as feature blooms rather than long-lasting bunch flowers. Their large size makes them dramatic in arrangements.
Cut flowers early in the morning when blooms are fully open. Place stems into clean, cool water immediately.
Common dinnerplate dahlia problems
Weak or broken stems
This usually happens when plants are not staked, or when flowers become heavy after rain. Stake early and tie stems as they grow.
Lots of leaves but few flowers
Too much nitrogen or too little sun can cause leafy growth with fewer blooms. Use a balanced feed and make sure plants get enough sunlight.
Tuber rot
This can happen if tubers are planted into cold, wet soil or watered too much before sprouting. Plant in warm, well-drained soil and avoid overwatering early.
Final thoughts
Dinnerplate dahlias are perfect if you want large, dramatic summer flowers. Give them sun, space, support and steady care, and they can become the highlight of your garden.
For the best results, plant at the right time, stake early and keep removing old flowers to encourage more blooms.
