Dahlia Cornel Brons

This variety is made for cutting thanks to its straight stems. However, only cut the flowers when they are three-quarters open and their back petals are firm to the touch and not wilted – they will not open any further in a vase once cut. A key trick of professional growers is to dip the ends of the stems in hot water (70–80 °C) for a full 15 minutes immediately after harvesting. This sudden temperature shock will reliably extend the vase life of the bouquet to about one full week.

Definitely yes. For dahlias, one very simple rule applies: the more you cut them, the more new flowers the plant will rapidly produce. Therefore, never let old flowers dry out on the stems. The plant would immediately begin to form seeds, which would needlessly and severely drain its energy at the expense of setting new buds. Regular pruning keeps the dahlia in full health and beauty until late autumn.

Yes, sturdy support is absolutely essential for this variety. The straight and strong stems reach shoulder height (80 to 160 cm) and carry relatively heavy, full flowers. Stronger summer winds or a sudden thunderstorm could easily break the fragile, tall stems. We therefore recommend driving sturdy stakes in next to the tubers right at the time of planting to avoid damaging the growing roots later, and gradually tying the plant to them as it grows.

Pinching is an absolutely key step to obtaining a wide, bushy plant and an enormous number of flowers. Once the young plant has developed a few pairs of true leaves and reaches a height of about 30 to 40 cm, simply remove the main terminal shoot with your fingers or clean scissors. Thanks to this intervention, the plant will immediately redirect its energy, branch out beautifully in all directions, and produce many more side buds throughout the season.

Dahlias are very sensitive to cold, so plant the tubers in an outdoor bed only in May or June, when there is no longer a risk of spring frosts. The ideal planting depth is about 10 to 15 cm. Place the tuber in the prepared hole, preferably horizontally, so that the eye (bud) is pointing upwards. Given the size of mature plants, strictly follow the recommended spacing of 30 to 50 cm, which corresponds to roughly 1 to 4 plants per square meter.

Watering should be regular but moderate; the soil must never be permanently waterlogged. Initially, after the first shoots emerge, support the plant with a quality nitrogen fertilizer for rapid development of strong foliage. However, as soon as the first small buds begin to form, switch immediately to a fertilizer with a high potassium content. Sufficient potassium ensures the overall strength of the stems and a stunning, rich terracotta color in all the flowers.

Yes, that is a great and very popular trick for having the first cut flower bouquets at the very beginning of summer. Plant the tubers early in the spring in spacious containers with a light substrate and place them in a bright spot inside the house. Once the danger of frost has passed in May, you can transplant already very strong and hardy plants with a perfectly developed root system outdoors, and they will begin to bloom much sooner.

Yes, even such a massive and tall variety can be grown in a container without any problems, but there are certain specifics to it. You will need a truly large, bulky, and heavy pot so that the mature plant with its support does not tip over in a gust of wind. The container must have sufficient drainage holes at the bottom and high-quality drainage material so the tubers do not rot. Also, remember that soil in a pot dries out much faster and loses valuable nutrients, so watering and fertilizing must be significantly more frequent than for plants in a garden bed.

Unfortunately, they will not. Dahlia tubers are not frost-hardy in our climatic conditions and would definitely not survive an outdoor winter in the soil. As soon as the first frost burns the green leaves in the autumn, cut the stems down low. Then, dig up the tubers very carefully with a spade or garden fork, clean off the coarse soil, and store them safely in a dry, frost-free area. They overwinter best packed in crates and covered with dry sand or peat.

Dahlias absolutely love the sun. Choose a fully sunny spot in your garden, where they will also be slightly protected from strong winds. The soil should be primarily nutritious, humus-rich, and well-draining. In the shade or in heavy, clayey, and waterlogged soil, the plants will languish, stretch tall reaching for the light, and produce only a minimum of flowers.

The most common cause of this problem is an excess of nitrogen in the soil. If you fertilize your Dahlia with a high-nitrogen fertilizer throughout the season, it will create a huge amount of beautiful green foliage and long stems, but it will not have the energy or proper nutrients left to produce flowers. Before the start of summer, it is necessary to switch to a fertilizer high in potassium and phosphorus. Another reason may be a lack of direct sunlight at the site or failing to pinch back the young plant at the beginning of its growth.

Hungry slugs are a huge threat to Dahlias, especially in the spring when the plants are just sprouting from the ground. They can literally destroy fresh and fragile shoots overnight. The key is early and regular hand-picking, ideally in the evening or early morning after rain. It is also very effective to sprinkle eco-friendly Ferramol granules around the sprouting tubers.

During the season, besides slugs, keep an eye out for unwelcome thrips, which like to suck sap from the leaves and young buds, subsequently causing unsightly deformation. Another major threat is the dangerous mosaic virus. It manifests itself through typical yellow-green mottling, noticeably curled leaves, and overall stunted growth of the plant. Unfortunately, there is no effective cure for viral diseases. If you detect an infection, you must immediately dig up the entire plant, including the tuber, and dispose of it safely (definitely do not add it to the compost) so that the insidious disease does not spread further.

There are two simplest ways to propagate Dahlia:

Division of tubers
In the spring, before planting, you can divide older, large clumps of tubers to propagate your Dahlias. Each separated piece of tuber must have a so-called neck with an eye (bud), from which a new plant will grow. The "potato" itself without an eye will not sprout. Let the cut surfaces dry or treat them with charcoal to prevent rot.

Cuttings
In February-March, lightly bury the Dahlia tubers in substrate and place them in a bright, warm spot (20+ °C). Expect that it may take a few weeks for the tuber to come to life; it varies by species, but 4-6 weeks is the general rule. Keep the substrate slightly moist, but not waterlogged. Once the shoots grow to a length of 5-8 cm and have at least two pairs of true leaves, they are ready. Cut the shoot using a sharp, clean knife. Remove the bottom leaves from the cutting (leave only the top pair). Dip the end of the cutting into a powdered rooting hormone. Insert the cutting into a seed tray or a small pot with light substrate. It is necessary to mist the cuttings regularly to help them root.