Roses prefer a slow-release nitrogen fertilizer to grow healthy and bloom adequately. They also like slightly acidic soil with a pH between 6 and 6.5.
Raw coffee grounds contain a considerable amount of nitrogen, making them an option for organically growing your roses. So, are coffee grounds good for roses?
Coffee grounds are good for roses because they act as a slow-release organic nitrogen fertilizer. They also deter pests like snails, slugs, and rabbits from damaging rose bushes. However, do not apply coffee grounds in excess or too close to your roses to avoid nitrogen burns that can kill the plants.
Benefits of using coffee grounds on roses
Roses require constant feeding as soon as the first leaves are out. They rely heavily on a nitrogen supply for bushy foliage and flashes of blooms.
As a rule of thumb, you can establish roses with a general purpose fertilizer, like a 5-10-10 10-10-10 for the first two times. Constant feeding and the correct soil pH are key to establishing healthy blooms.
Organic soil amendments using coffee grounds ensure the correct pH and constant feeding. The grounds also offer other benefits to your roses as follows:
- Coffee grounds feed roses with slow-release nitrogen.
- They attract micro-organisms that feed on them, thus loosening up the soil to improve its structure, drainage, aeration, and water retention.
- Coffee grounds have a pH range of 6.5 to 6.8 pH, which is ideal for rose plants.
- Applying coffee grounds in rose bushes deters pests like slugs, snails, and rabbits.
- Coffee grounds are a good organic remedy for fungi on plants.
Nutrients in coffee grounds
Here’s the nutrient composition of coffee grounds by volume:
Coffee grounds also contain micronutrients that are beneficial for roses, including zinc, iron, magnesium, boron, copper, and calcium.
How to use coffee grounds on roses
My recommendation is to only work composted coffee grounds into the soil as an amendment for it to be of any benefit to your rose plants. Otherwise, apply fresh grounds in a mulch layer while avoiding direct contact with your plants since they are known to be detrimental to plants.
Here’s how to use coffee grounds on rose plants:
You can make a liquid coffee fertilizer and use it as a nitrogen feed for roses as soon as you see their first leaves. Here’s how to make it:
- Add 2 cups of raw coffee grounds into 5 gallons of water.
- Stir to mix and let the mixture sit for 1 to 2 days.
- Spray the liquid fertilizer around the root zone of your roses.
Can use soluble fertilizer from coffee grounds to feed roses growing in pots.
Composting coffee grounds
Add about 20% of coffee grounds in volume to your compost. Mix well and allow it to “cook” for a few months. Work the compost into the soil to amend it before planting your roses.
An alternative way of composting coffee grounds is to layer your ingredients using 1/3 leaves, 1/3 fresh grass clippings, and 1/3 coffee grounds.
Note: Studies have found that the pH of decomposing coffee grounds is not stable. You shouldn’t use the dregs as a soil pH amendment for your roses.
Sprinkling in mulch
Sprinkle spent or raw coffee grounds on top of mulch, covering the area around your roses. Be careful not to go too close to the stem, as contact will kill your rose plants.
The grounds have soluble nitrogen that’ll release slowly into the soil to feed your rose plants.
- Fresh coffee grounds are toxic to plants (phytotoxic). Do not apply them near the stems of your roses to avoid killing them.
- Do not add thick layers of compacted coffee grounds around rose plants. They will form a barrier to air and moisture.
- Excessive application of coffee grounds can lead to nitrogen burns in your rose plants.
Roses like coffee grounds, but only when applied correctly and in the right amounts. You can apply the grounds as a liquid fertilizer or by sprinkling the dregs on top of mulch in your rose gardens. Composting with 20% coffee grounds is also a good way to utilize the grounds to make organic fertilizer.
PS: See also my article on vegetables that like coffee grounds here.