I’ve been wanting to grow elderberry bushes soon and I’ve heard they like acidic soil, so I was wondering if coffee grounds would make a good fertilizer for them. Here’s what I found.
Coffee grounds are great for elderberry bushes as they have essential nutrients such as nitrogen, potassium, and phosphorus. They also promote beneficial soil life such as mycorrhizal fungi. Remember to apply a maximum of 2 cups per plant and mix with other organic matter to avoid soil compaction and mold.
So, while coffee grounds are good for elderberry bushes, which nutrients do they provide, and is their acidity (and caffeine) an issue? Let’s find out.
3 Benefits of Coffee Grounds For Elderberry Bushes
Here’s a list of nutrients found in coffee grounds:
By far the most potent nutrient in coffee grounds is nitrogen (at about 2%). This might not seem like a lot, but it adds up quickly in the soil.
This is good news as nitrogen is the primary nutrient plants require (along with phosphorus and potassium, together making “NPK”).
2. Acidic pH
As with most plants, elderberries prefer a slightly acidic soil pH (4.7-5.2). This is because a slight acidity dissolves the nutrient solids in the soil and makes them accessible to the plant’s finer roots.
This is because a slightly acidic soil helps dissolve the nutrient solids in the soil, making them accessible to the plant’s finer roots.
Fourteen of the seventeen essential plant nutrients are obtained from the soil. Before a nutrient can be used by plants it must be dissolved in the soil solution. Most minerals and nutrients are more soluble or available in acid soils than in neutral or slightly alkaline soils.Donald Bickelhaupt, SUNY College of Environmental Science and Forestry
|Used Coffee Grounds||Fresh Coffee Grounds|
|pH of 6.8||pH of 5.5-6.8|
The best ways to measure your elderberry’s soil pH are with strips or a meter. I prefer using a pH meter since they’re affordable and easy to use. If you’d like to see which meter I use and recommend, see my recommended tools page.
Fortunately, coffee grounds are fairly acidic, but they should be brewed or composted first to remove the excess caffeine.
If you find that your elderberry’s soil pH is too acidic (below 4.5), consider adding alkaline materials to the soil like biochar, powdered lime, or wood ash.
On the other hand, if your elderberry’s soil pH is too alkaline (above 5.5), use acidic amendments such as sand, onion skin, or peat moss.
3. Water Retention, Temperature Regulation, and Pest Repellant
Coffee grounds also help elderberries by increasing the soil’s water retention and temperature regulation (similar to compost). For example, every 1% increase in the soil’s organic matter leads to an additional 20,000 gallons of water held per acre.
Coffee grounds are also said to help repel some pests such as snails and slugs.
Thanks to how small coffee grounds are, they quickly decompose in the soil, becoming swift food for worms and other beneficial soil life. This decomposition process can be as quick as 1-2 weeks (especially in vermicompost bins) but can take as long as 3+ months.
How to Use Coffee Grounds on Elderberry Bushes
|Under 2 Cups||Over 2 Cups|
|Apply directly to the soil||Add to compost pile (no more than 20-35%)|
|Spread out in a thin layer to avoid mold||Wait 3 months for decomposition|
Before using coffee grounds in your garden, I recommended brewing them first (if you haven’t already) to remove most of the caffeine and excess acidity.
Apply Directly to the Soil
If you have under 2 cups of coffee grounds, apply them directly to your elderberry bushes’ soil by spreading them out in a thin layer.
It’s recommended to have a layer no higher than 1/2 an inch and to keep the coffee grounds at least 3 inches from your elderberry’s stems. Doing this improves aeration and sunlight exposure, reducing the chance of mold building up and affecting your plant.
Keep in mind, high levels of caffeine can be harmful to beneficial insects such as earthworms and pollinators. Since caffeine is a natural pesticide made by plants, avoid using too many coffee grounds in vermiculture bins or other beneficial insect areas.
During times when you have a lot of coffee grounds, it’s usually better to compost them first.
If you have over 2 cups of coffee grounds, add them to your compost pile. After 3 months, the coffee grounds should be free of caffeine and decomposed enough to be used in your garden.
Here’s what a gardening expert has to say about using composting coffee grounds.
Composting coffee grounds is the best thing to do before putting them in the garden. Use no more than 20-35 percent by volume of coffee grounds in a compost pile.Lisa Ogden, University of Wyoming
Since coffee grounds are a “green” material (nitrogen-based), they can make a compost pile stinky if used in excess. To balance this, add “brown” materials (carbon-based), such as leaves, sawdust, or wood chips.
Place the carbon materials on top of your compost pile to reduce and eliminate smells and flies. The finer the carbon material the fewer the bugs and stink.
Fortunately, coffee grounds don’t have as much nitrogen as other materials. Coffee grounds have a great carbon-nitrogen ratio (20-24:1), so they don’t need much carbon to become balanced.
For example, the famous permaculture farmer Joel Salatin recommends compost piles to have a carbon-nitrogen ratio of 30:1, so coffee grounds aren’t too far off on their own.
10 Other Kitchen and Yard Scraps for Elderberry Bushes
Eggshells are high in calcium, which is an essential element for developing elderberry plant’s cell walls.
Crushing these shells before adding them to the compost accelerates their decomposition and makes the calcium readily available to the plants, leading to stronger and healthier elderberries.
2. Banana Peels
Banana peels contain lots of potassium, phosphorus, and magnesium, all essential nutrients for healthy plant growth and development. Just chop them up and bury them around your raspberry plants, and watch them thrive.
3. Vegetable Peels and Scraps
Various essential nutrients are present in vegetable scraps, like potassium, phosphorus, and other trace elements. Potassium and phosphorus are key for plant metabolism and energy transfer, while trace elements play diverse roles in plant health, growth, and fruit development.
4. Citrus Peels
Orange, lemon, and other citrus peels are rich in nitrogen and potassium and can help lower the pH of the soil, making it more acidic. This is perfect for your elderberry bushes, which prefer slightly acidic conditions.
5. Corn Cobs
These decompose slowly, gradually adding valuable organic material to your compost. This enhances the soil structure, providing better water retention and aeration for your elderberry plant’s root system.
6. Leafy Green Scraps
These provide high amounts of nitrogen, essential for chlorophyll synthesis and thus leafy growth. Trace minerals from these scraps also support various biochemical processes within your elderberry plants.
7. Leaves and Grass Clippings
Leaves and grass clippings provide nitrogen, which serves as a food source for soil microorganisms and promotes plant growth.
Layering these materials with other compost ingredients can help maintain a proper balance of carbon and nitrogen in your compost pile.
8. Avocado Peels and Pits
Avocado scraps are rich in potassium, fiber, and other nutrients that can help improve soil health. Fiber aids in soil structure and moisture retention, while the nutrients from avocado waste feed your elderberries and support their growth.
9. Melon Rinds
Melon rinds, like those from watermelon or cantaloupe, contribute to the moisture balance in your compost. Their decomposition also provides various essential plant nutrients, supporting the growth and development of your elderberries.
10. Carrot Tops
Carrot scraps, including tops and peels, are a great source of potassium and can help improve soil structure. Just add them to your compost pile or directly bury them in your elderberry bed for a nutrient boost.
Need More Help?
You can always ask us here at Couch to Homestead, but you should know the other resources available to you! Here are the resources we recommend.
- Local Cooperative Extension Services: While we do our best with these articles, sometimes knowledge from a local expert is needed! The USDA partnered with Universities to create these free agriculture extension services. Check out this list to see your local services.
- Permaculture Consultation: Need help with a bigger project? Send us a message.