Whether you should fertilize your roses with coffee grounds or stay away from it is a sensitive issue among hobby gardeners. We therefore list the most common advantages and disadvantages of natural fertilizer.
Fertilize roses with coffee grounds: the advantages at a glance
The coffee grounds offer many benefits for roses. The household remedy is a valuable source of nitrogen and can promote the sprouting and leaf formation of the roses. In addition, nitrogen also supports the formation of flowers and also supplies the flowers with phosphorus, potassium and copper. The coffee grounds can also lower the pH of the soil, making the soil slightly acidic – just right for the lush flowering shrubs.
Loosen and improve the soil
If you use the natural fertilizer, you can use it to loosen the soil and improve its permeability. In addition, the coffee grounds can replace the mulch layer on potted plants and prevent the moisture in the substrate from evaporating. This enables the development of a healthy root system and the absorption of the necessary nutrients through the roots.
Young plants in particular have difficulty rooting in loamy soil. The fine roots of the young plants are also very sensitive and react badly to waterlogging. Coffee grounds ensure good drainage, so that the irrigation water and rainwater can run off.
Coffee grounds provide food for earthworms
Furthermore, coffee grounds are not only useful for the plants themselves, but also for soil life and can really work wonders. It provides food for earthworms that improve the soil. The worms also loosen the garden soil and make it airier. The tunnel system of the worms is used by the roots of the roses. This allows the roots to penetrate deep into the soil. This way the shrubs are much more stable and can withstand even a storm. In addition, they are able to absorb water from deeper soil layers during longer dry periods in summer. All in all, the plants become more robust.
Fertilize roses with coffee grounds and drive away slugs
For many hobby gardeners, the coffee grounds also prove to be a good remedy against pests. Slugs in particular are a real threat to roses and can even eat larger bushes. However, the caffeine in coffee grounds is toxic to reptiles. It’s true that the caffeine in coffee grounds isn’t in large enough amounts to kill the slugs. Despite this, many gardeners report that the critters intuitively avoid it. You can therefore prevent an infestation.
The coffee grounds are also said to have antibacterial properties. It should therefore kill germs and accelerate the healing of diseased plants. There is no scientific evidence for this.
What speaks against using coffee grounds as fertilizer for roses?
Opponents of coffee grounds have their arguments. Above all, the limited scientific evidence for certain effects of coffee grounds is one reason why many hobby gardeners do without it. These include, among other things:
- Coffee grounds have a limited, primarily deterrent effect on slugs. However, it cannot kill or deter spider mites, aphids and the like.
- Coffee grounds are said to have antibacterial properties. But it can also kill the beneficial bacteria and fungi in the soil, making plants more susceptible to germs.
- Don’t just replace mulch with coffee grounds, as the latter can form an air and moisture impermeable layer over time. Much better is sprinkling coffee grounds around the root area and then covering with compost.
- The caffeine in coffee grounds can also stunt plant growth, and the high levels of nitrogen can burn roots.
- One Study from Oregon should also add to the negative effect on seed formation and seed germination.
Can you fertilize roses with coffee grounds: In these cases it makes sense
As with all fertilizers, it is advisable to use coffee grounds in moderation. A bit of coffee grounds at the right time can speed up growth, too much of a good thing can kill the plants.
When is the right time to fertilize the roses?
The best time to fertilize roses with coffee grounds is in spring, when the plants start growing. This gives the natural fertilizer enough time to penetrate deep into the soil and supply the soil with nitrogen. However, you must use the coffee grounds as an aid – it is certainly not a miracle cure and can damage plants in high doses. The rule of thumb is: if in doubt, it is better to use a conventional fertilizer from the garden center. At the very least, this will ensure that your weakened or ailing plants are getting all the necessary ingredients they need to grow.