Americans drink around 146 billion cups of coffee every year. If it takes 2 tablespoons of coffee grounds to make 1 cup of coffee, that’s nearly 4.8 trillion gallons of coffee grounds every single year.
Naturally, gardeners want to avoid waste as much as possible, and will seek ways to use kitchen waste to fertilize their flowers and vegetables.
Used coffee grounds are not only a free fertilizer, but they can compete with other organic fertilizers like alfalfa meal for fertilizing your broccoli. And unlike other kinds of kitchen waste, you can easily add coffee grounds directly into your soil without composting or worrying about attracting animals.
Should You Use Coffee Grounds for Broccoli?
Coffee grounds make an excellent soil amendment for broccoli as well as many other vegetables. Broccoli in particular is a heavy feeder and can benefit from additional organic fertilizer.
Used coffee grounds are a gentle fertilizer so it’s not easy to overfertilize and burn your broccoli plants.
Furthermore, coffee grounds, like any organic matter, will also improve the structure and moisture-retention properties of your soil.
Pro-Tip: One lesser known fact is that many coffee shops are willing to give you their used coffee grounds for free. Big chains like Starbucks have been doing this for years. Ask politely if you can take a few bags of used coffee grounds off their hands.
Nutrient Profile of Coffee Grounds
Used coffee grounds are not a strong fertilizer, but for a single-ingredient soil amendment, they’re packed with nutrients for your broccoli.
Coffee grounds have a good amount of nitrogen in them and small amounts of phosphorus and potassium. Most of the nitrogen is instantly available to your broccoli, while the rest will be released over time as soil life decomposes the coffee.
Coffee also has important plant micronutrients such as iron, calcium, magnesium, and chromium.
How to Use Coffee Grounds to Fertilize Broccoli
You can apply coffee grounds before you plant your broccoli or top dress throughout the season.
Amending Soil with Coffee Grounds Before Planting Broccoli
If you have a lot of coffee grounds, you can prepare your broccoli bed before planting with up to 1 inch (2.5 cm) of coffee grounds and work it into the soil with a shovel, rake, or hand cultivator.
Make sure you mix it with the soil, as a thick layer of dried coffee grounds will repel water.
How to Top Dress Broccoli Beds with Coffee Grounds
If you already have broccoli in the ground, you can top dress with coffee grounds. Top dressing means sprinkling fertilizer on top of the soil, and mixing it into the top inch or so of soil.
Top dressing broccoli works because most of the nitrogen will be readily taken up by your broccoli, which is important for stem and leaf growth, while the remaining nutrients slowly release throughout the season.
To top dress broccoli, add around 1 to 2 tablespoons of used coffee grounds per square foot around your plants, and gently work it into the top inch or so of soil. Apply once a week up to once a month throughout the season.
Related Questions About Using Coffee Grounds in the Garden
What Is the NPK of Coffee Grounds?
As discussed above, used coffee grounds are a very gentle fertilizer and a good source of nitrogen. Estimates vary, but you can expect an NPK value of approximately 2.1-0.3-0.3, which puts it in line with a lot of commercial single-ingredient organic fertilizers like alfalfa meal.
Are Coffee Grounds Acidic? Will They Affect the pH of My Soil?
While coffee is acidic, after you brew your coffee, most of the acid is leached out of the grounds. Used coffee grounds are almost neutral (around pH 6.5 to 6.8) and will not affect the pH of your soil in low or even moderate amounts.