In order for the dahlia to delight us with its beautiful flowers, it needs a few extra nutrients. We show what you should consider when fertilizing dahlias. Originating from South America, dahlias (dahlias) transform your garden into a shining sea of flowers from July until the first frost in autumn.
The queen of late summer shows a great variety of flower colors, shapes,s, and sizes. From large pompon-shaped flowers to pointed, narrow flowers like those of the cactus dahlia, everything is represented. But no matter which variety you choose, the striking flowering beauty has to be adequately supplied. So it can develop its magnificent flowers over the summer.
Why Do Dahlias Need Fertilizer?
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Dahlias need sufficient nutrients because they belong to the group of heavy eaters. This is no wonder, considering that this pretty ornamental plant produces a completely new mass of leaves and impressive flowers every spring and displays them until autumn. Above all potassium and phosphorus are important for this and must also be provided organically or mineral.
Of course, nitrogen, the third important nutrient component, must not be missing. However, too much nitrogen can cause the plant to put its strength mainly into strong leaf growth and neglect the flowering. To prevent this from happening, we will show you what fertilization options are available and how best to proceed.
Do you want to learn the professional methods of Dahlias growing? You will find them in this article.
When Should You Fertilize Dahlias?
Fertilizing depends on the right timing. The first nutrient enrichment begins in the fall, long before the dahlias are planted in the soil. This happens in spring when the danger of frost is over. In autumn, after the frost-sensitive tubers have been dug up, the soil can already be loosened and mixed with well-decomposed manure or ripe compost. The first proper fertilization is then carried out in spring to give the flowering beauty a good jump-start directly.
When exactly the fertilization takes place depends on the type of fertilization. While organic fertilizer such as ripe compost is already worked into the soil before planting, mineral fertilization is applied a few weeks after planting, after the young shoots have appeared.
The second fertilization is then carried out in July when mineral and organic fertilization are applied, just before the flowering stage, to give it a final push to produce particularly beautiful flowers. No more fertilization should be applied from the end of August. Otherwise, the tubers cannot ripen sufficiently and their shelf life is endangered. This is especially true of nitrogen-rich fertilizers.
What Is The Best Fertilizer For Dahlias?
You can fertilize your dahlias with organic, mainly organic or mineral fertilizers. Organic fertilizers such as compost or manure are of plant or animal origin and are more sustainable in their production. Through their natural release in the soil, they ensure an even flow of all necessary nutrients and a healthy soil life.
Mineral fertilizers are produced from fossil raw materials and atmospheric nitrogen and also contain nutrients such as nitrogen, phosphorus, and potassium. They are usually available to the plants more quickly, but if they are applied in the wrong dosage, over-fertilization can occur more easily.
In addition, excess nutrients can be washed out into the groundwater much more easily, so more attention must be paid to the dosage. Also for some other reasons, mineral fertilizers such as blue grain are not optimal, which you can read more about in our article about mineral fertilizers.
Fertilize Dahlias Primarily Organically: Instructions For Application
Organic fertilization not only has a positive effect on the plant but also improves the soil, which is why it is generally preferable to mineral fertilization. Dahlias love loose, warm, and humid soils that have good water drainage. If your soil does not meet these conditions, you can bring it closer to this idea with the help of mainly organic fertilization.
If you fertilize your dahlias primarily organically, the first application is best done two weeks before planting. Here it is a good idea to mix two hands of well-decomposed compost per tuber with the plant soil. Other organic fertilizers such as horn meals can also be used. However, since the horn meal contains little potassium, potassium- and phosphorus-rich fertilizers should be used in addition.
To make sure that everything goes smoothly when fertilizing, we have written a short instruction for our organic flower fertilizer for you.
Step-by-step instructions for fertilizing dahlias:
- Place the dahlia tuber in the planting hole and cover with the enriched soil
- Pour on well, so that the granules can soften and the microorganisms have better access
- In July, before the start of flowering, add a further 80 – 120 g/m² of flower fertilizer
Mineral Fertilizer For Dahlias With Blue Grain
If you prefer to use mineral fertilizers, it is sufficient with slow-release fertilizers to supply the ornamental plant with additional nutrients twice during the growing season. The first application takes place about four weeks after planting, when the young shoots appear, to give the plant a small energy boost. The second dose is then given in July before the start of flowering for, particularly splendid flowers.
However, if you use a cheaper mineral fertilizer without long-term effects, 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 that the seeds are not distributed on 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 soils. We strongly advise against using only mineral fertilizer. Sustainable gardening and a corresponding, long-term healthy soil life only work if soil organisms are supported by organic fertilization.
Fertilizing dahlias with household remedies
Do you like to drink coffee? Then you already have a good household remedy for fertilizing dahlias with your coffee grounds. Fertilizing with coffee grounds brings nitrogen into the soil and creates a slightly acidic ph-value, which dahlias, as well as roses (pink), hydrangea, or violets (viola), tolerate well.
And the fertilizer made from coffee grounds has another advantage: it keeps away the snails, which are particularly fond of the young shoots of the dahlias. It also magically attracts earthworms, which are a welcome guest in any 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. For drying, you can simply spread the coffee grounds flat overnight on a tray or plate.