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Things to know about dahlias
Botanical name: Dahlia x hortensis
Other names: garden dahlia, georgia
Use: garden plant, balcony plant, container plant, cut flower, cemetery plant
Origin: Central America
Flowering period: June to the first frost in November
Flower colors: yellow, orange, cream, red, pink, white, violet, two-colored and double varieties
Special features: The daisy family delight with an abundance of infinitely many different colors and shapes. Depending on the type of flower, a distinction is made between decorative dahlia, cactus dahlia, mignon dahlia or ball dahlia. All species enchant with a unique abundance of flowers in summer and well into autumn.
Dahlias originally come from Central America and have their own genus in the daisy family with 28,000-30,000 different varieties worldwide. The dahlia became popular when Europeans discovered America. However, many of the species were not classified with cultivar names until the last century. The flowering plant was named after the Swedish botanist Andreas Dahl, who was a student of Linnaeus. The herbaceous plants are perennial, but not hardy in our climatic conditions. This means that they can be planted in the garden or in a pot from May to Octobercan stand and must be overwintered frost-free. The tuber of the dahlia serves as a storage organ and enables the ornamental plant to sprout again. With unusual flower shapes and diverse flower colors, dahlias provide an incomparable flair. The beauty is easy to plant. Furthermore, the large flowers are fantastic, have a long flowering period, are easy to care for and bloom plentifully. Dahlias are also ideal for decoration and as cut flowers. Discover our plants online shop.
In which location do dahlias feel most comfortable?
The classics prefer a sunny location, but also thrive in partial shade. A well-drained and nutrient-rich soil with a pH value of approx. 6.5 is important for a rich bloom. Waterlogging should be avoided. Improve loamy soil with some sand so that excess water can run off better.
Dahlia tubers can be planted out in the bed or beautify the balcony or terrace as a container plant. An even water supply is important for lush flowering in the right location.
It is best to combine the flowering plants with grasses or ornamental foliage perennials to show off the beautiful flowers particularly well.
With us you will find the right planters outside.
Important tip: Using compost on the bed can improve the soil structure. However, since the nutrient content in the compost varies, it is unsuitable as the sole growing medium in pots.
How do I plant dahlias in the garden?
Dahlia tubers are sensitive to frost, so you should only plant them from the end of April or start indoors from the end of March. Storage organs from the previous year can also be taken out of the winter quarters from March. Before planting, water the tuber for half a day. Use a peat-sand mixture for the pre-culture and ensure there is sufficient light and temperatures of 10 to 15 degrees Celsius. Pre-grown plants should be gradually adapted to outdoor conditionsbecome accustomed to. The best time to change location is from the beginning of May on cloudy days to avoid sunburn. However, make sure that there is no longer any risk of frost. Or you can buy ready-made plants and place them directly in your own garden or in larger containers for the balcony and terrace. By repotting, you give the flowering plant a larger root volume and reduce the watering effort. Use good quality potting soil for transplanting and add a layer of expanded clay to the pot for better drainage. You can buy plants online from us.
Our gardening tip: Depending on the size of the bulb, dig a sufficiently deep planting hole. After planting, put a layer of three to five centimeters of soil on the storage organ. If planted too deep, the plants will sprout poorly. The planting distance is 20 to 40 cm for low bed types, 60 to 70 cm for medium high and 80 to 100 cm for high types.
How do I care for my decorative dahlia in summer?
In addition to watering and fertilizing, a cut is also part of the right care in summer. You should regularly remove faded flowers so that new flowers can develop.
When so-called trimming, cut back all faded stems down to the last well-developed pair of leaves. This prevents unnecessary seed formation, improves the formation of new flowers and extends the flowering period.
After pruning, the flowering plant will soon sprout again in the leaf axils and other flowers will delight with their wonderful colors. Even as pot plants, it is important that you care for and cut the summer flowers accordingly.
Care tip: Above all, varieties with a growth height of more than 60 cm should be tied up with perennial rings or sticks and sisal cord. This avoids wind breakage and the magnificent plants are adequately supported.
How do I water dahlias correctly?
The easy-care plants tolerate a lot, but it is important that regular watering takes place. Planted out in the bed, the root ball is well branched and on nutrient-rich soils with a high humus content, watering is only necessary in dry phases without precipitation. On light sandy soil, watering every 2 to 3 days may be necessary in summer. It is helpful here if the soil is improved with high-quality potting soil when planting. In hot summer weeks, the daisy family needs enough water to be able to come up with flowers permanently. It is best to always water the plants directly on the ground, never about leaf or flower. How often you have to water depends largely on the temperature, the sunlight and the size of the root ball.
How do I fertilize my dahlia tubers?
Dahlia are luxuriant in growth and bloom in summer. Sufficient nutrients are necessary for good growth and flowering. It is best to put flower bulb power in the planting hole when planting in spring. This special fertilizer contains fragrances and neem, which acts as a protection against voles. In addition, the contained mycorrhizal fungi promote root formation and thus ensure an optimal supply of the plants. You can also use natural fertilizers as organic fertilizers that work slowly. Fertilization is particularly important when cultivating in pots and containers, as this can quickly lead to a lack of fertilizer. Therefore, you should change the potted plants every 2 to 3 weeksfertilize with a high-quality liquid flower fertilizer. Make sure the root ball is well moistened to avoid root damage.
How does propagation take place?
The easiest way to propagate the daisy family is by dividing the tuber. You can simply divide older plants with a sharp knife or spade before planting in spring. Another option is to take cuttings. For this purpose, the tubers are planted indoors in spring and the young shoots are cut as cuttings after they have sprouted. Cuttings root optimally in seed trays or in a seed set with a transparent cover. After 3 to 4 weeks the first roots have formed and the young plants can be repotted in pots with potting soil. You can buy potting soil from us. After a phase of hardening, the young dahlia plants can be planted outdoors from mid-May.
How do I overwinter my summer flowers properly?
Dahlias are sensitive to frost and after nights with temperatures below 0 °C the leaves are frozen. If you want to enjoy the plants again next year, we recommend overwintering them in a frost-free place.
In late autumn, cut back the plants to 5 to 10 cm and carefully dig up the tubers. Put the tubers in wooden boxes and cover them with sand. Hibernation should take place indoors in a cool and dry place.
Temperatures of 4 to 8 degrees Celsius are ideal, because if they are stored too warmly, the tubers will dry out and will not sprout well in the coming year.
Our gardening tip: the tubers store nutrients for the coming year. It is therefore important that they had sufficient time to store the storage substances. Therefore, do not take the tubers out of the ground too early. The best time is mid to late October.
Can I also use dahlias as cut flowers?
Especially tall varieties are suitable as cut flowers, because here many stems can be harvested per plant. Dahlia flowers keep very well in the vase and are a delight as cut flowers with a shelf life of 5 to 7 days.
What other types are there?
With its typical flower, the genus is a member of the daisy family. The large number of varieties is divided into classes or groups based on the type of flower or the height of growth. In addition to single-flowering varieties, there are a large number of characteristic flower shapes, such as semi-cactus dahlias, star, pompom, anemone or water lily dahlias and decorative dahlias. Based on the growth height, there are two main groups that should be considered, especially with regard to the purpose:
low growth up to 80 cmhigh growth up to 1.80 mbedding and container plantSolitary plant in the garden, cut flowerneeds little spaceneeds up to 1 m² of spacesimple variety as bee pasture
fascinate with their unique flower shapes
Time — consuming breeding work keeps creating new varieties. Due to the wide range of flower shapes and types as well as growth heights, classic plantings in the garden or as a container plant in pots and window boxes can be done, depending on taste.
What pests and diseases can the dahlia get?
Dahlia are insensitive and free-flowering summer flowers, but they can be attacked by the following diseases and pests:
Especially the first shoots of the tubers are a delicacy for slugs in May. An infestation can be easily recognized by the slime traces on the leaves. A layer of shells or a snail tape can help. If the summer flowers are 15 to 20 cm high, the greatest danger is over and the voracious pests cause less damage.
The fungal disease occurs on the foliage and flowers and is usually a result of cold, wet weather. A gray spore coating forms at the rotten spot. Remove the affected plant parts and keep the plants drier. The summer flowers are strengthened by multiple spraying with bio-active agent with field stalk and oats and renewed infestation with fungal diseases is minimized.
FAQ — Frequently Asked Questions
Which other plants are suitable for the combination?
Grasses, perennials and structural plants, which give the colorful flowering plants the right setting, are ideal for the combination. It is important that the companion plants feel comfortable in sunny and nutrient-rich locations. Combinations with other flowering plants are attractive if you create either tone-on-tone combinations or plantings with complementary colors.
You can see an example of tone-on-tone planting with dahlias in the picture.
Can dahlias be propagated from seed?
You can propagate the daisy family from seeds you have collected or bought yourself. Growing dahlias from seeds is possible, but requires a little patience and finesse.
Are there species that are suitable for the balcony or for a small garden?
Many of the commercially available varieties are ideal for a container or balcony box. In addition to a sufficiently large container and a sunny location, an even water supply and regular fertilization are important. Varieties that grow up to 50 cm high are particularly suitable for the container garden.
Are there dahlias that are suitable as insect host plants?
With simple dahlias you offer bumblebees, hoverflies, butterflies and bees a valuable food source for many weeks.
Can dahlias overwinter outdoors?
Dahlia plants are sensitive to frost. Leaves and flowers already suffer at temperatures around freezing point. The tuber can tolerate frost for a short time, but must be stored in a protected, frost-free place over the winter. A new shoot will follow next spring. There are no hardy dahlias. We therefore recommend planting out after the last frosts from mid-May and harvesting the storage organs in autumn. It is important that you do not dig up the rhizomes too early, because the storage of nutrients takes place until late autumn and the autumn classics continue to grow and form new buds until September.
Why aren’t my dahlias blooming?
The flowering is sparse, especially in locations that are too shady. In addition, the daisy family needs sufficient water, fertilizer and humus-rich soil for a rich abundance of flowers. Regularly cutting out faded flowers also ensures faster and more abundant reblooming.