Are Coffee Grounds Good for Roses?
Coffee grounds can provide some benefits for roses, but they should be used with caution and in moderation. Here’s a closer look at the nutritional benefits and soil impact of using coffee grounds for roses:
Nutrient Content of Coffee Grounds
- Coffee grounds contain about 2% nitrogen, 0.06% phosphorus, and 0.06% potassium, along with small amounts of micronutrients like magnesium, iron, and calcium.
- Contrary to popular belief, coffee grounds do not significantly acidify the soil. They have a pH of around 6.5, which is close to the ideal pH range for roses (6.0-6.5).
- Coffee grounds can provide nutrients that benefit soil microbes, which in turn help plants absorb nutrients. They also have antioxidant and antimicrobial properties that can suppress plant diseases like Fusarium wilt.
How to Use Coffee Grounds for Roses
- Sprinkle no more than ½ to 1 inch of coffee grounds into the top couple of inches of soil around your roses, and work them into the soil to avoid forming a water-resistant barrier.
- Adding coffee grounds to your compost is the best method, as they should not make up more than one-fifth of the compost in volume. Once composted, they can be used liberally around roses without concerns.
- Use coffee grounds in moderation to avoid temporary nitrogen shortages in the soil. High doses can burn roots and stunt growth due to caffeine content.
Are Eggshells Good for Roses?
Eggshells can provide some benefits for roses, but they are not a primary source of essential nutrients. Here’s what you need to know:
Nutrient Content of Eggshells
- Eggshells are primarily composed of calcium (about 34%), with smaller amounts of magnesium, sodium, phosphorus, and potassium.
- Eggshells can slightly raise soil pH levels if used in large quantities, which could reduce the plant’s ability to absorb other essential nutrients like phosphorus, potassium, iron, and zinc.
How to Use Eggshells for Roses
- Directly applying eggshells to the soil is not very effective due to their slow decomposition rate. It is better to mix them into your compost where they can gradually decompose and provide nutrients.
- Mixing eggshells into compost allows them to break down and provide calcium and other nutrients more effectively.
- There is little risk in using eggshells, but they should not be relied upon as a primary source of calcium. Overuse can raise soil pH levels, which may negatively impact nutrient absorption.
Comparing Coffee Grounds and Eggshells to Other Fertilizers
- Coffee grounds are not a replacement for balanced fertilizers that contain nitrogen, phosphorus, and potassium (NPK). They are high in nitrogen but lack significant amounts of phosphorus and potassium, which are crucial for blooming and overall plant health.
- Eggshells are not an effective immediate source of calcium compared to other fertilizers. If your roses have a calcium deficiency, quicker and more effective methods of addressing it should be used.
In conclusion, coffee grounds and eggshells can provide some benefits for roses, but they should be used in moderation and as part of a balanced fertilization program. It’s important to consider the specific nutrient needs of your roses and use these organic materials judiciously to support their growth and health.
