Feeding dahlias: the right fertilisation for perfect blooms
For dahlia to enchant us with their beautiful flowers it needs a few extra nutrients. We show you what you need to observe when feeding dahlias.
Native to South America, dahlias (Dahlia) will transform your garden into a brilliant sea of blooms from July until the first autumn frost. The queen of late summer does so with a great variety of flower colour, shape and size. From large pompon-shaped flowers to pointed, narrow flowers like those of the cactus dahlia, there is something for all tastes. But whatever variety you choose, the eye-catching flowering beauty must be adequately cared for. In this way, it can continue to show its magnificent blossoms throughout the summer.
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Why do dahlias need fertiliser?
Dahlias need sufficient nutrients because they belong to the group of heavy feeders. This is not surprising when you consider that this pretty ornamental plant produces a completely new mass of leaves and striking flowers every spring and displays them right through to autumn. Especially potassium and phosphorus are important for this and must be additionally provided organically or in mineral form. Nitrogen, of course, must not be missing as the third important nutrient component. Too much nitrogen, however, can lead to the plant pouring most of its energy into strong leaf growth and neglecting flowering. To make sure that does not happen, we’ll show you what fertilisation options are available and the best way to go about it.
When should you feed dahlias?
Fertilisation is all about the right timing. The first nutrients should be added in autumn, long before the dahlias are planted in the soil. This is in spring, when there is no longer any danger of frost. In autumn, after digging up the frost-sensitive tubers, the soil can already be loosened and mixed with well-rotted stable manure or mature compost. The first proper fertilisation is then carried out in the spring to give this stunning flowering plant a good start.
When exactly fertilisation takes place depends on the type of fertilisation. While organic fertilisers such as mature compost are worked into the soil before planting, mineral fertilisers are added only a few weeks after planting, once the young shoots have appeared. The second fertilisation is then carried out with mineral and organic fertilisers in July, shortly before flowering, to give it a final boost to produce particularly beautiful flowers. From the end of August, no more fertiliser should be added. Otherwise, the tubers will not be able to ripen sufficiently and their storability will thus be compromised. This is especially true of nitrogen-rich fertilisers.
- Perfect for flowering plants in the garden & on the balcony
- For healthier plants with beautiful & long-lasting blossoms
- Long-lasting fertiliser that is free from animal products - child & pet friendly
What is the best type of fertiliser for dahlias?
You can feed your dahlias with organic fertiliser, primarily organic or mineral fertiliser. Organic fertilisers, such as compost or manure are of plant or animal origin and more sustainable in production. Through their natural release in the soil, they ensure a steady flow of all necessary nutrients and healthy soil life. Mineral fertilisers are made from fossil raw materials and nitrogen from the air and also contain nutrients such as nitrogen, phosphorus and potassium. As a rule, they are available to the plants more readily, but this can also make it easier to over-fertilize if the wrong dosage is used. In addition, excess nutrients can be leached into groundwater much more easily, so more attention must be paid to dosage.
Feeding dahlias with natural fertilisers
Natural fertilisation is not only beneficial to the plant but also improves the soil, which is why it is generally preferable to mineral fertilisation. Dahlias love loose, warm and moist soils that have good water drainage. If your soil does not meet these conditions, you can bring it closer to this ideal with the help of primarily organic fertilisation.
If you are feeding primarily organic fertiliser to your dahlias, the first application is best carried out two weeks before planting. It is a good idea to mix two hands of well-rotted compost per tuber with the planting soil. Other organic fertilisers such as horn meal can also be used. However, since horn meal contains only a small amount of potassium, additional fertilisers containing potassium and phosphorus should be added. Our Plantura Flower Food, for example, provides an extra portion of potassium, which supplies the plant with all the important nutrients over a long period of time and does not contain any animal ingredients. The second fertilisation can then be carried out in July before flowering begins with Plantura Liquid Flower Food.
- Perfect for all flowers & balcony plants
- Liquid fertiliser for a lush blossom throughout the season
- Quick & easy application - child & pet friendly
To make sure that fertilisation goes smoothly, we have put together a short guide for our Plantura Flower Food for you.
Step-by-step instructions for feeding dahlias:
- Mix Plantura Flower Food with the planting soil: 100 – 150 g of fertiliser per m² of area to be covered
- Place the tuber in the planting hole and cover with the enriched soil
- Water well to soften the granules and give the micro-organisms better access
- In July, before the start of flowering, re-fertilize once more with 80 – 120 g/m² of our Plantura Flower Food
- Perfect for flowering plants in the garden & on the balcony
- For healthier plants with beautiful & long-lasting blossoms
- Long-lasting fertiliser that is free from animal products - child & pet friendly
Feeding dahlias with mineral fertilisers
If you prefer to apply mineral fertilisers, with slow-release fertilisers it is sufficient to provide this ornamental plant with additional nutrients twice during the growing season. The first dose should be given approximately four weeks after planting, when the young shoots appear, to give the plant a small boost of energy. The second dose can then be given in July before flowering to ensure particularly magnificent blooms. However, if you use a cheaper mineral fertiliser without long-term effect, the fertiliser should be applied in small doses every 4-6 weeks for a uniform supply. With all mineral fertilisers, be careful not to spread the grains 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. For this reason we strongly advise against using mineral fertilisers only. Sustainable gardening and an associated long-term healthy soil life only works if soil organisms are encouraged through organic fertilisation.
Fertilising dahlias with home remedies
Do you like to drink coffee? Then you already have a good home remedy for fertilising dahlias with your coffee grounds. Fertilising with coffee grounds adds nitrogen to the soil and its addition creates a slightly acidic pH, which dahlias tolerate well, as do roses (Rosa), hydrangeas (Hydrangea) or violets (Viola). And fertilising with coffee grounds brings another plus: it keeps away the slugs, which are especially partial to young shoots. Moreover, it has a magical attraction for rain worms, which are a welcome guest in any garden soil. For fertilisation, the coffee is worked flat into the soil. It is important to let it dry out beforehand, as it can otherwise start to form mould very quickly in the flowerbed. To dry, you can simply spread the coffee grounds out flat on a tray or plate overnight.
Tip: Coffee grounds alone, of course, are not sufficient as a full fertiliser for the highly voracious dahlia. So if you want to add some extra value to your coffee fertiliser, you can mix it, for example, in a ratio of 3:1 with our Plantura Flower Food.
Are you also interested in the care of dahlias? Then check out our dedicated article for all the information and tips you need on caring for dahlias.
