Coffee Grounds Vs. Banana Peels: Which Natural Fertilizer Is Better For Roses?

If you've ever looked up tips and tricks for growing beautiful roses, you've probably seen advice to use kitchen leftovers like coffee grounds and banana peels as fertilizer. But if you had to pick between them, which option actually helps roses more? The answer depends on two things: what type of nutrients your roses require, and what nutrients your soil is missing.

It helps to understand what roses need. Roses are delicate and require a consistent balance of nutrients if they are to thrive. They need nitrogen to keep their leaves lush and green, phosphorus to fuel root and flower growth, and potassium to grow quickly and produce big, show-stopping blooms. So, how do coffee grounds and banana peels actually stack up against these needs? 

Coffee grounds don't provide a significant amount of nutrients, but they do provide a little bit of the basics. They contain 2% nitrogen, 0.06% phosphorus, and 0.6% potassium by volume, plus a handful of other micronutrients. Banana peels, on the other hand, have lower ratios of nitrogen and phosphorus, but they are potassium bombs.

To get an idea of what your roses need most, test your soil first to learn about its nutrients and pH levels. There are other ways to identify nutrient deficiencies in plants, but a soil test will pinpoint any major problems. Sometimes the issue is not a lack of nutrients, but a pH imbalance that can decrease roots' ability to absorb nutrients. Different rose types will have different ideal levels, but roses generally prefer a soil pH between 6.0 and 7.0.

Once you have the soil test result, you can decide whether your roses need coffee grounds or banana peels. If your soil is lacking in nutrients overall, coffee grounds are the better choice. However, if the test reveals a lack of potassium, banana peels will be more effective. As for timing, coffee grounds should be added to rose beds in the spring after the danger of frost has passed; before spring, the temperature and microbial activity levels may be too low to break down organic matter in soil. Meanwhile, banana peel fertilizer is best applied during bud development, which is when roses need potassium the most to promote flowering. 

However, don't just drop a banana peel next to your rose bush. Doing this can attract pests and, as microorganisms work to decompose the peel, decrease the amount of nitrogen available in the soil. Compost banana peels or create liquid fertilizer with them instead. Likewise, don't put fresh coffee grounds straight into the soil. They contain phytotoxic compounds that can kill rose plants, so they'll need to be composted for a few months before they can be applied safely.