Coffee grounds are a popular choice for gardens—they’re known for adding nutrients, boosting soil health, and even helping to keep some pests away. But while they might sound like a miracle solution, they’re not a perfect fit for every plant. In fact, some plants can actually struggle when coffee grounds are mixed into their soil.
In this guide, we’ll explore why coffee grounds can be a great addition to your garden, which plants don’t get along with them, and how to use them wisely without causing harm to your greenery.
Why Use Coffee Grounds in the Garden?
Coffee grounds can be a great tool for gardeners, offering a simple way to boost soil health naturally. Here’s why many people love using them:
- Nutrient-Rich Fertilizer: Coffee grounds are loaded with nitrogen, a key nutrient for plants. Nitrogen helps plants produce chlorophyll, giving leaves their vibrant green color and fueling photosynthesis. For some plants, this extra nitrogen can be a real game-changer.
- Improves Soil Structure: Adding coffee grounds to soil boosts its structure by improving drainage, moisture retention, and airflow. This makes it easier for roots to grow strong and healthy, which is key for plant development.
- Pest Deterrent: Coffee grounds can even help keep pests like slugs and snails away. Their rough texture creates a barrier that many pests just don’t want to cross, helping to keep your plants safe.
But coffee grounds aren’t perfect. Their acidity and ability to hold moisture can make them a bad match for certain plants. So, let’s check out which plants might struggle with coffee grounds and why.
What Plants Don’t Like Coffee Grounds?
While coffee grounds can be a great boost for many gardens, some plants just don’t like the extra acidity they bring to the soil. Here are 7 plants that do better in neutral to alkaline soils and aren’t fans of coffee grounds:
Lilacs: Lilacs love slightly alkaline soil and don’t do well with the acidity that coffee grounds can add. This extra acidity can lower the soil’s pH, making it hard for lilacs to flourish. To keep their blooms beautiful, use lime or other pH-balancing materials instead of coffee grounds.
Asparagus: Asparagus, a long-lasting vegetable, prefers a more alkaline soil. Coffee grounds can make the soil too acidic, which can stunt its growth and lead to smaller harvests. Instead, try adding crushed eggshells or garden lime to keep the soil pH balanced.
Forsythia: Forsythia is a tough shrub that likes its soil neutral to slightly alkaline. Coffee grounds can shift the soil pH to be too acidic, which might lead to fewer flowers and slower growth. To keep your forsythia thriving, use neutral mulches like shredded bark or composted leaves.
Russian Sage: Russian Sage is perfect for dry, alkaline soil and less fertile spots. Coffee grounds can change the soil’s pH, making it more acidic and less ideal for this rugged plant. Gravel mulch or organic compost is a better choice to maintain the right pH for Russian Sage.
Phlox: Phlox thrives in slightly alkaline to neutral soils and can struggle if the pH gets too low. Coffee grounds can make the soil more acidic, reducing its growth and blooming. To keep phlox happy, use composted plant material or limestone to maintain a balanced pH.
Yucca: Yucca plants are adapted to thrive in alkaline soils, often found in dry regions. The acidity from coffee grounds can disrupt their growth and make them prone to root problems. Using sand or crushed stone as a soil amendment helps provide good drainage and keeps the pH just right.
Rosemary: Rosemary loves soil that drains well and leans slightly alkaline. Coffee grounds can hold too much moisture and shift the pH, making it tougher for rosemary to grow. A mix of composted bark or coarse sand works better to maintain the right soil conditions for this fragrant herb.
Tips for Using Coffee Grounds for Plants
Coffee grounds can be a fantastic addition to your garden when used the right way! Here are some tips to help your plants thrive with coffee grounds:
- Compost First: Before adding coffee grounds to your garden, compost them. This helps neutralize their acidity, making them friendlier for more plants, especially those that don’t like changes in pH.
- Mix with Other Organic Materials: Don’t use coffee grounds on their own. Blend them with other composted materials like leaves or straw to balance their effects. This keeps the soil from becoming too acidic or loaded with nitrogen.
- Use in Moderation: A light layer of coffee grounds can act as a nice mulch, but too much can block airflow and water from reaching the roots. Aim to keep coffee grounds at about 10-20% of your total compost mix.
It’s also super important to keep an eye on how your plants respond to coffee grounds. Look out for these signs that might mean something’s off:
- Yellowing Leaves: This could mean the soil is too acidic or there’s a nutrient imbalance.
- Slow Growth: If your plant’s growth starts to slow down after adding coffee grounds, it might be due to changes in soil pH or too much nitrogen.
- Wilting or Drooping: This might indicate root rot from too much moisture being held in the soil.
If you spot any of these issues, it’s best to stop using coffee grounds and switch to a more neutral mulch or compost. Happy gardening!
Alternatives to Coffee Grounds
If you’re worried about the possible downsides of using coffee grounds, don’t fret! Here are some great alternatives to consider:
- Eggshells: Crushed eggshells are a fantastic choice—they add calcium to the soil without messing with the pH like coffee grounds do.
- Composted Kitchen Scraps: A mix of vegetable peels and other kitchen scraps offers a balanced nutrient boost to your soil, helping your plants thrive.
- Aged Manure: Well-rotted manure is a top-notch all-purpose soil amendment that won’t cause the same pH fluctuations as coffee grounds.
To Sum it Up
Knowing which plants don’t get along with coffee grounds can really help you make better choices in your garden. While coffee grounds are a fantastic source of nutrients and organic matter, they’re not a fit for every plant out there. By spotting the species that are sensitive to coffee grounds and following best practices for their use, you can keep your garden healthy and thriving.
So, the next time you brew a cup of coffee, think twice before tossing those grounds into the soil—your plants will definitely appreciate it!
Frequently Asked Questions
Where should coffee grounds not be used in the garden?
Avoid using coffee grounds on plants that are just starting to grow or in freshly seeded areas. The caffeine in coffee grounds can slow down the growth of young plants, especially those that prefer alkaline or neutral soil pH. It might end up doing more harm than good by keeping seeds from sprouting properly.
What pests don’t like coffee?
Slugs, ants, and snails. Bees, wasps, and fleas. These pests tend to avoid areas where coffee grounds are used.
