I used to think coffee grounds were a great, easy fertilizer—until I made the mistake of using too much. My poor Calathea didn’t love that! After a lot of trial and error, I finally figured out the right way to use them without causing harm.
So, do Calatheas (prayer plants) like coffee grounds? Yes, but only in small amounts. Used coffee grounds add nutrients, but too much can lower soil pH too much or cause mold. The best way to use them? Mix with compost and apply lightly—no more than once every 4–6 weeks—while keeping the soil’s pH in check (6.5–7.0).
Want to avoid the mistakes I made? Stick with me—I’ll walk you through the do’s and don’ts, plus some even better options!
Coffee Grounds for Calathea Plants: Benefits and Risks
Potential Benefits
Coffee grounds can offer several benefits to plants when used properly. Here’s how they might help your Calathea:
- Nutrient Boost: Coffee grounds contain small amounts of nitrogen, potassium, and magnesium, which are essential for plant growth.
- Improved Soil Texture: When mixed into soil, coffee grounds can improve drainage and aeration, helping roots grow better.
- Organic Matter: Coffee grounds break down over time, adding organic material to the soil and encouraging microbial activity.
Quick Tip: Always use used coffee grounds. Fresh grounds can be too acidic and may harm your plant.
Risks of Using Coffee Grounds
While coffee grounds have benefits, they come with risks, especially for Calathea plants:
- Soil Acidity: Calathea prefers soil with a neutral to slightly acidic pH (6.5–7.0). Overusing coffee grounds can lower the pH too much, making the soil too acidic for Calathea.
- Mold Growth: Coffee grounds can retain moisture, increasing the risk of mold if not properly composted.
- Over-fertilization: Adding too many coffee grounds can overwhelm your plant with nutrients, leading to browning leaf tips or slowed growth.
Checklist:
- Use in moderation.
- Mix coffee grounds with compost.
- Test soil pH regularly.
How to Use Coffee Grounds for Calathea Safely
If you want to use coffee grounds for your Calathea, follow these steps to do it safely:
Step 1: Prepare the Coffee Grounds
- Collect used coffee grounds. Let them cool completely.
- Dry the grounds to prevent mold.
- Mix the coffee grounds with compost or other organic matter. This reduces the risk of acidity and ensures even nutrient distribution.
Step 2: Apply in Moderation
- Add a thin layer of the mixture to the topsoil.
- Avoid applying directly to the plant base to prevent root damage.
- Use sparingly, no more than once every 4–6 weeks.
Pro Tip: Monitor your plant for signs of stress, like yellowing leaves, after applying coffee grounds.
Step 3: Test Soil pH
- Use a soil pH testing kit to ensure the soil stays in the ideal range (6.5–7.0).
- Adjust the pH as needed by balancing coffee grounds with other soil amendments like compost or peat moss.
Alternatives to Coffee Grounds for Calathea
If you’re unsure about using coffee grounds, here are some safe alternatives:
Compost
Compost is a nutrient-rich option that adds organic matter to the soil without altering pH drastically. It’s also eco-friendly and promotes healthy microbial activity.
Vermicompost
Also known as worm castings, vermicompost provides a gentle, slow-release fertilizer. It’s perfect for Calathea, which prefers consistent but not excessive nutrients.
Peat Moss or Coconut Coir
These materials improve soil moisture retention and texture, ensuring your Calathea gets the perfect balance of water and air.
Comparison Chart:
| Amendment | Benefits | Best Use Case |
| Coffee Grounds | Adds nitrogen, organic matter | Use sparingly with compost |
| Compost | Nutrient-rich, balances soil pH | Safe for all soil types |
| Vermicompost | Gentle, slow-release fertilizer | Sensitive plants like Calathea |
| Peat Moss/Coir | Retains moisture, improves texture | Dry or compacted soils |
FAQs About Calathea Coffee Grounds
Do Calatheas Like Coffee Grounds in Pots?
Yes, in moderation. Coffee grounds can add nutrients, but too much can make the soil too acidic. Mix with compost and use sparingly for best results.
Can Coffee Grounds Harm Calathea Plants?
Yes, if overused. Coffee grounds can lower soil pH too much or lead to mold growth. Always mix with compost and use in moderation.
How Often Can I Use Coffee Grounds for Calathea?
You can use coffee grounds once every 4–6 weeks. Mix them with compost for safe application.
What Are Signs of Over-Fertilization in Calathea?
Look for browning leaf tips, yellowing edges, or stunted growth. These are common signs of too much fertilizer.
Are There Better Ways to Feed Calathea?
Yes! Compost, vermicompost, and balanced liquid fertilizers are safer and easier to manage for Calathea.
Do Calatheas Like to Be Misted?
Yes, Calatheas enjoy humidity, and light misting can help. However, avoid over-misting to prevent mold or mildew.
Wrapping It Up
Coffee grounds can benefit Calathea plants when used responsibly, but they’re not the only option. Mixing coffee grounds with compost, applying sparingly, and testing soil pH are crucial steps to ensure your plant thrives.
If you’re hesitant, alternatives like vermicompost or peat moss are excellent choices.
Thinking about getting a Calathea? Start with this What is a Calathea Plant? A Complete Beginner’s Guide
Happy Gardening!
Additional Resources:
- University of Florida- Calathea Production Guide
- National Library of Medicine- Biochemical and Physiological Characteristics of Photosynthesis in Plants of Two Calathea Species
