Rose fertiliser

Why do rose bushes need fertiliser?

By supplying mineral elements, fertilisers nourish the plant. They encourage its growth and promote generous, abundant flowering, which in turn is more colourful. They make the plant stronger and more resistant to diseases and parasitic pests. Fertilisers reduce risk of chlorosis (yellowing of foliage caused by a deficiency or by an absorption problem of certain mineral elements, such as iron). Some fertilisers also include a relating-to-root growth stimulant, which improves establishment and promotes good rooting of the bush.

Fertilisers are made up of three main elements: nitrogen (N), phosphorus (P) and potassium (K), each with a role in vegetative growth, flowering and fruiting, disease resistance or rooting. For each fertiliser, the percentage of each of these three elements is given (for example: a 12-7-10 fertiliser contains 12% nitrogen, 7% phosphorus and 10% potassium). They may also include secondary elements and trace elements, in smaller quantities. Fertilisers are frequently enriched with magnesia, for example.

For roses (as well as for other flowering bushes), favour fertilisers rich in potassium. This element promotes generous, abundant flowering.

Fertilisers are not necessarily chemical or harmful to environment. Natural options exist (horn meal, blood meal…), suitable for organic farming.

It is important, however, to respect dosages, as excess fertiliser is harmful and can burn roots.

Potted roses have greater needs than those planted in open ground: with limited substrate volume, they depend on watering and fertilisation provided. The substrate is depleted more quickly, making repotting (or top-dressing) and fertiliser application necessary.

Rose ‘Chartreuse de Parme’

When and at what frequency should fertiliser be applied to rose bushes?

At planting

We recommend applying fertiliser at planting. Choose a basal granular fertiliser that will release minerals very gradually. You can also simply add manure or compost if available; these will improve soil texture, make it lighter and more aerated, improve water retention and enhance micro-organism activity.

Ongoing care

Thereafter, apply fertiliser during the growing season: from March to September. In winter, roses are dormant, so fertilising is unnecessary.

If you notice chlorosis or nutrient deficiency (foliage turns yellow, especially between veins), apply a kick-start liquid fertiliser. Minerals supplied will be immediately available to plants. If necessary, you can also apply a foliar anti-chlorosis fertiliser to spray onto foliage (repeat every three weeks if necessary).

Liquid fertilisers should obviously be applied more frequently than slow-release granular fertilisers. The former supply minerals that are immediately available to plants and do not persist long in soil. They are perfect for a quick boost. Apply every 15 days.

By contrast, for slow-release granular fertilisers, one application every three months is sufficient. This allows three applications per year: late winter–early spring, summer and early autumn, bearing in mind that fertilising in winter is unnecessary. These slow-release granular fertilisers are less likely to burn roots.

How to fertilise roses?

• To apply liquid fertiliser, it’s very simple: just dilute it in the watering water. The dosage to follow is indicated on the bottle. We recommend moistening the substrate beforehand, because if the soil is dry, roses may absorb too large a quantity of fertiliser at once, which can burn their roots.
• For granular fertilisers: scrape the soil around the plant, then place the granules and cover with 2–3 cm of potting compost, then water. Nutrients are released into the soil through watering, so it is important to water regularly.
• There are also fertiliser sticks: simply insert them into the pot, pushing them in at the edge of the pot. The number of sticks to use is indicated on the packaging, according to the pot diameter.

Take care not to overdose, and avoid applying fertiliser near a watercourse. These precautions are all the more important for liquid fertilisers, which are rapidly leached.

Climbing rose ‘Albertine’

Which fertiliser should I choose for potted roses?

For potted roses, you can choose fertilisers in granular, stick or liquid form, but favour small pack sizes, which are more suitable (packets of 500 g or 1 kg, for example, or liquid fertilisers in 1 L bottles). Similarly, dosage must be more precise than for roses in open ground.

Flowering Plant UAB Stick Fertilizer in a pack of 25 blisters

This fertiliser for flowering plants, suitable for organic farming, is convenient due to its packaging as sticks. Simply insert a few into the pot. Its formulation is 4-3-8 + 2 MgO. However, reserve for smallest roses, as it already requires 4 sticks for a pot only 16 cm in diameter.

See the product sheet

Engrais liquide Rosiers Or Brun en flacon de 1L

This liquid fertiliser is very easy to use, as you simply dilute 10 mL per 1 L of water. Its NPK formulation is 3-3-6, so it is richer in potassium than in phosphorus and nitrogen, which promotes flowering. It acts quickly and needs to be applied every 15 days.

See the product sheet

Promesse de Fleurs Fertiliser for Roses and Flowering Bushes, 500g box

This fertiliser comes in granular form, with NPK formulation 3-2-5 + 2 MgO. It is enriched with magnesium oxide and also contains a root growth stimulator. Apply every three months, from spring to autumn.

See the product sheet

Finally, if you prefer a very natural formulation, choose La Belle Bouse. This fertiliser is available in small pack sizes (250 g, 500 g…), which makes it very practical.

Which fertiliser should I choose for roses in open ground?

For roses in open ground, we first recommend adding well-rotted manure or compost at planting, which you will mix into soil or if none is available, choose directly a granular fertiliser, such as those listed below.

You can also add mycorrhizae at planting :

Mycorhize Top Pouss Arbres et arbustes en doypack de 150 g

Mycorrhizae are a sym symbiosis between a fungus and a plant, which helps the plant absorb water and mineral nutrients (root absorption surface is multiplied by 1,000!). Mycorrhizae improve the efficiency of fertilisers and make plants more resistant.

See the product sheet

Thereafter, apply during growth, approximately every three months, a granular fertiliser :

Fertilisant La Belle Bouse - Engrais naturel 100% BIO et local

We recommend this very natural fertiliser, made from cow dung. It is well suited to roses in open ground. Its formulation is NPK 2.5 – 1.8 – 3, and it also contains trace elements. Available in 1kg or 3kg bags.

See the product sheet

Rose Fertiliser NPK 11-10-17 + 3MgO

This fertiliser has the advantage of being enriched with Magnesium Oxide at 3%. Easy to use and particularly suited to roses, simply spread the granules on the soil, cover lightly and water. This fertiliser is also available in 1kg mini-packs.

See the product sheet

Engrais Rosiers et Arbustes à fleurs Solabiol

With an NPK formulation of 3-2-5 + 2 MgO, this fertiliser, suitable for organic farming, is an excellent solution to feed your roses. It is enriched with Magnesium Oxide and also includes a root growth stimulator. It releases mineral nutrients gradually for long-lasting action.

See the product sheet