In order for the dahlia to please us with its beautiful flowers, it needs a few extra nutrients. We show what you should consider when fertilizing dahlias.
Native to South America, the Dahlias (Dahlia) transform your garden into a bright sea of blossoms from July until the first frost in autumn. The queen of late summer shows a wide variety of flower colour, shape and size. Everything is represented, from large pompom-shaped flowers to pointed, narrow flowers like those of the cactus dahlia. But whichever variety you choose, the eye-catching flowering beauty must be adequately cared for. This allows her to develop her magnificent flowers over the summer.
Why do dahlias need fertilizer?
Dahlias need sufficient nutrients because they belong to the group of heavy consumers. That's no wonder when you consider that the pretty ornamental plant develops new leaves and impressive flowers every spring and keeps them on display until autumn. Potassium and phosphorus in particular are important for this and must also be made available organically or minerally. Of course, nitrogen must not be missing as the third important nutrient component. Too much nitrogen, however, can mean that the plant puts its energy into strong leaf growth and flowering is neglected. To make sure that doesn't happen, we'll show you the options for fertilization and the best way to proceed.
When should you fertilize dahlias?
The right timing is important when fertilizing. The first nutrient accumulations begin in autumn, long before the dahlias are planted. This only happens in the spring, when the danger of frost has passed. In autumn, after the frost-sensitive tubers have been dug up, the soil can already be loosened and mixed with well-rotted stable manure or mature compost. The first real fertilization takes place in spring to give the flowering beauty a good jump-start.
When the fertilization takes place exactlydepends on the type of fertilization. While organic fertilizers such as mature compost are worked into the soil before planting, mineral fertilizers are only applied a few weeks after planting, after the young shoots have appeared. The second fertilization is then carried out with mineral and organic fertilization in July, shortly before flowering, in order to give it a last boost to particularly beautiful flowers. From the end of August there should be no more fertilization. Otherwise the tubers cannot mature sufficiently and their storability is thus endangered. This is especially true for fertilizers rich in nitrogen.
What is the best way to fertilize dahlias?
You can fertilize your dahlias organically, primarily organically or minerally. Organic fertilizers such as compost or manure are of plant or animal origin and more sustainable in production. Due to their natural release in the soil, they ensure an even flow of all necessary nutrients and a he althy soil life. Mineral fertilizers are made from fossil raw materials and atmospheric nitrogen and also contain nutrients such as nitrogen, phosphorus and potassium. They are usually available more quickly for the plants, but this can also lead to over-fertilization if the wrong dosage is used. In addition, excess nutrients can be washed out into the groundwater much more easily, which is why more attention must be paid to the dosage. Mineral fertilizers such as blue grain are also not ideal for a number of other reasons, which you can read about in more detail in our article on mineral fertilizers.
Dahlias primarily fertilized organically: instructions for application
Organic fertilization not only has a positive effect on the plant, but also improves the soil at the same time, which is why it is generally preferable to mineral fertilization. Dahlias love loose, warm and moist soil that has good drainage. If your soil does not meet these conditions, you can bring it closer to this ideal with the help of primarily organic fertilization.
If you primarily fertilize your dahlias organically, the first dose is best given two weeks before planting. Here it makes sense to mix two hands of well-rotted compost per tuber with the potting soil. Other organic fertilizers such as horn meal can also be used here. However, since horn meal contains little potassium, fertilizers that are high in potassium and phosphorus should also be used.Our Plantura organic flower fertilizer, for example, provides an extra portion of potassium, which provides the plant with all the important nutrients over a long period of time and completely dispenses with animal ingredients. The second fertilization can then be done in July before the start of flowering with the Plantura flower & balcony fertilizer.
So that everything works when fertilizing, we have written a short guide for our organic flower fertilizer for you.
Step-by-step instructions for fertilizing dahlias:
- Mix Plantura organic flower fertilizer with the potting soil: 100 - 150 g fertilizer per m² of area to be covered
- Place the dahlia bulb in the planting hole and cover with the enriched soil
- Water well so that the granules can soften and the microorganisms have better access
- In July, before flowering begins, fertilize again with 80 - 120 g/m² of our Plantura organic flower fertilizer
Fertilize mineral dahlias with blue grain and Co.
If you prefer to use mineral fertilisers, it is sufficient to supply the ornamental plant with additional nutrients twice during the vegetation period with long-term fertilisers. The first dose is given about four weeks after planting, when the young shoots appear, to give the plant a small boost of energy. The second dose is then in July before the start of flowering for particularly magnificent flowers. However, if you use a cheaper mineral fertilizer without a long-term effect, the fertilizer should be applied in small doses every 4-6 weeks to ensure an even supply. With all mineral fertilizers, care must be taken to ensure that the grains are not spread over open roots or directly on the main shoot.
In general, it is important to keep in mind that Dahlias do not tolerate heavy, wet or cold soil. We strongly advise against exclusively mineral fertilization. Sustainable gardening and the associated, long-term he althy soil life only works if soil organisms are promoted by organic fertilization.
Fertilize dahlias with home remedies
Do you like coffee? Then you already have a good home remedy for fertilizing dahlias with your coffee grounds. Fertilizing with coffee grounds brings nitrogen into the soil and by adding it creates a slightly acidic pH value, which dahlias as well as roses (Rosa), Hydrangeas (Hydrangea) or violets (Viola) are well tolerated. And the fertilizer made from coffee grounds has another plus point: it keeps the snails away, which eat the young shoots of the dahlias in particularlike. It also magically attracts earthworms, which are welcome guests in every garden. For fertilization, the coffee is worked flat into the soil. It is important not to forget to dry it beforehand, otherwise it can quickly start to mold in the bed. To dry, you can simply spread the coffee grounds out flat on a tray or plate overnight.
Tip: Coffee grounds alone are of course not sufficient as full fertilizer for the heavily consuming dahlia. So if you want to upgrade your coffee fertilizer a bit, you can mix it with our Plantura organic flower fertilizer in a ratio of 3:1, for example. Are you also interested in caring for dahlias? Then you will find all information and tips about dahlia care in our special article.