Your used coffee grounds can be a secret weapon for gardening success. Rich in nitrogen and organic matter, coffee grounds can condition soil, improve drainage, feed beneficial microbes, and even deter pests.
Plants That Like Coffee Grounds
However, they are not a cure-all, and knowing which plants love coffee grounds is essential to get the best results.
In this post, I will discuss 17 plants that benefit from coffee grounds, how to apply them correctly, and why moderation is key.
Why Use Coffee Grounds in the Garden?
Nutrient-Rich Organic Material
Used coffee grounds contain approximately 2% nitrogen by volume, along with trace amounts of phosphorus, potassium, calcium, and magnesium.
These nutrients are slowly released into the soil, supporting healthy plant growth over time without the sharp spikes of synthetic fertilizers.
Improves Soil Structure
Coffee grounds increase aeration in compact clay soils when worked into garden beds or composted.
They also improve moisture retention in sandy soils and enhance the soil’s ability to hold nutrients, particularly when combined with compost.
Encourages Earthworms
Coffee grounds create a moist, nutrient-dense environment that attracts earthworms. These natural tillers aerate the soil, increase nutrient availability, and break down organic material more efficiently.
Mild Acidity for Acid-Loving Plants
While fresh coffee grounds are quite acidic (around pH 5), used coffee grounds are only slightly acidic (pH 6.5–6.8), making them ideal for plants that thrive in mildly acidic conditions.
May Repel Pests
The coarse texture and caffeine content of coffee grounds may deter common garden pests like slugs, snails, and ants when scattered lightly around plant bases.
How to Use Coffee Grounds Safely
Best Practices for Application
Compost first for safety: Mixing coffee grounds with high-carbon materials (e.g., leaves, straw, shredded newspaper) creates a balanced compost pile that won’t burn plants or alter pH unpredictably.
Top-dress sparingly: Sprinkle a thin layer (¼ to ½ inch) around the base of plants, then gently mix into the topsoil.
Make coffee ground “tea”: Steep 2 cups of used grounds in 5 gallons of water overnight, then water plants with this mild liquid fertilizer.
Common Mistakes to Avoid
Avoid thick layers: Coffee grounds compact easily, creating a barrier that can repel water and promote mold growth.
Don’t apply fresh grounds directly: The high acidity and caffeine content in unused grounds can damage roots and inhibit seed germination.
Limit use around seedlings: Young plants are more sensitive to caffeine and inconsistent pH levels.
17 Plants That Like Coffee Grounds
1. Azaleas
Preferred Soil pH: 4.5–6.0
How Coffee Helps: Coffee grounds maintain the slightly acidic soil conditions azaleas need to uptake iron and other micronutrients. They also support microbial life and retain moisture in organic-rich soil.
Application Tip: Apply composted coffee grounds in early spring before new growth appears. Repeat mid-season to support blooms. Azalea growing guide.
2. Rhododendrons
Preferred Soil pH: 4.5–6.0
How Coffee Helps: These broadleaf evergreens flourish in acidic, humus-rich soils. Nitrogen from coffee fuels leafy growth, while the grounds improve moisture balance around shallow roots.
Application Tip: Blend coffee grounds into bark mulch or leaf compost and apply around the root zone, avoiding direct stem contact.
3. Blueberries
Preferred Soil pH: 4.5–5.5
How Coffee Helps: Blueberries are one of the most acid-loving fruiting plants. Coffee grounds help lower the pH, making iron and other minerals more available for berry production and strong foliage.
Application Tip: Use in spring and early summer; avoid applying near harvest time to prevent taste alteration. Combine with pine bark or pine needles for ideal results.
4. Hydrangeas (Especially for Blue Blooms)
Preferred Soil pH: 5.2–5.5 for blue flowers
How Coffee Helps: The aluminum in soil becomes available at lower pH levels, turning pink hydrangeas blue. Coffee helps maintain that acidity while contributing nutrients that support flower and leaf development.
Application Tip: Apply early in the season and reapply every 4–6 weeks to maintain pH levels.
5. Camellias
Preferred Soil pH: 5.5–6.5
How Coffee Helps: Camellias have shallow roots that thrive in rich, slightly acidic, and moisture-retaining soils. Coffee improves texture, encourages beneficial fungi, and helps roots absorb nutrients more efficiently.
Application Tip: Incorporate into mulched beds along with pine needles for best results.
6. Gardenias
Preferred Soil pH: 5.0–6.0
How Coffee Helps: These fragrant, acid-loving shrubs can become chlorotic (yellow-leaved) if the soil is too alkaline. Coffee restores the acidity and improves the soil’s nutrient profile.
Application Tip: Mix into compost and apply monthly during the growing season to maintain deep green foliage and abundant flowers.
7. Roses
Preferred Soil pH: 6.0–6.5
How Coffee Helps: Roses demand rich, well-fed soil. Nitrogen from coffee promotes dark green leaves, while phosphorus and potassium in trace amounts support blooming.
Application Tip: Sprinkle grounds around the base of the plant in early spring, then cover with compost or mulch to prevent crusting. Roses growing and care guide,
8. Tomatoes
Preferred Soil pH: 6.0–6.8
How Coffee Helps: Coffee grounds offer nitrogen for early vegetative growth, but must be balanced with phosphorus and potassium to support fruit production.
Application Tip: Add composted coffee grounds to the soil before planting. Avoid heavy applications during flowering to prevent overgrowth of foliage.
9. Carrots
Preferred Soil pH: 6.0–6.8
How Coffee Helps: Coffee grounds improve loose soil structure, allowing roots to grow deep and straight. Nutrients support steady, even development.
Application Tip: Mix into seedbed soil before sowing to prevent compaction and encourage uniform growth.
10. Radishes
Preferred Soil pH: 6.0–7.0
How Coffee Helps: Similar to carrots, radishes benefit from crumbly soil and added organic matter. Nitrogen supports early foliage, which in turn fuels root growth.
Application Tip: Add to compost or work into raised bed soil 2–3 weeks before sowing seeds.
11. Kale
Preferred Soil pH: 6.0–7.5
How Coffee Helps: Kale is a heavy nitrogen feeder. Coffee provides a sustained boost of nitrogen, encouraging full, dark green leaves and dense nutrition.
Application Tip: Use every 2–3 weeks in composted form during the active growing season.
12. Spinach
Preferred Soil pH: 6.0–7.0
How Coffee Helps: This cold-hardy leafy green thrives in nutrient-dense soils. Coffee’s nitrogen content promotes lush leaf growth.
Application Tip: Sprinkle into garden rows before planting and top-dress again after the first harvest to encourage regrowth.
13. Lettuce
Preferred Soil pH: 6.0–6.8
How Coffee Helps: Lettuce needs moisture and rich, loose soil to develop crisp, tender leaves. Coffee grounds improve soil texture and feed soil microbes.
Application Tip: Blend with composted manure and leaf mold for a nutrient-packed garden bed.
14. Beans
Preferred Soil pH: 6.0–6.8
How Coffee Helps: Beans fix their own nitrogen, but benefit from the improved organic matter and microbial support that coffee grounds provide.
Application Tip: Apply only composted coffee grounds around plants once they are established to avoid interfering with nitrogen-fixing bacteria.
15. Hostas
Preferred Soil pH: 6.0–7.0
How Coffee Helps: These shade-loving perennials enjoy rich, slightly acidic soils. The gritty texture of coffee grounds may also help deter slugs, a major pest of hostas.
Application Tip: Apply grounds as a mulch ring around the base, keeping away from the crown to prevent rot.
16. Evergreens (Pine, Spruce, Fir, Juniper)
Preferred Soil pH: 5.0–6.5
How Coffee Helps: Many evergreens evolved in acidic forest soils rich in decomposed needles and bark. Coffee mimics this environment and supplies slow-release nutrients.
Application Tip: Spread composted grounds in early spring around the drip line to feed the tree as it wakes from dormancy.
17. Lilies
Preferred Soil pH: 6.0–6.5
How Coffee Helps: Lilies benefit from nitrogen during early growth and improved drainage in heavier soils. Coffee grounds contribute both.
Application Tip: Use composted grounds as part of a soil mix for containers or in-ground beds; apply during the active growing season.
Plants That Dislike Coffee Grounds
Avoid using coffee grounds with plants that prefer alkaline or dry, sandy soils, including: Lavender, Sage, Thyme, Aloe vera, Orchids, Geraniums, and Asparagus.
Also, do not apply around young seedlings, as caffeine and acidity can hinder early development.
Final Tips for Success
- Test your soil pH before committing to regular coffee ground use.
- Combine with compost or other organic materials to buffer acidity and avoid compaction.
- Start small and observe plant reactions. Adjust frequency and amount based on performance.
- Store used coffee grounds properly in a sealed container or compost pile to prevent mold.
Final Thoughts
Used coffee grounds are an easy, eco-friendly way to nourish your garden when used thoughtfully. By matching the right plants with coffee’s natural properties, you’ll see greener foliage, stronger roots, and better blooms.
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