Can I use coffee grounds for cucumbers?
Written by
Paul Reynolds
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.To grow cucumbers with coffee grounds successfully, a proper balance is key. Used grounds provide nitrogen and drainage improvement. I mix in 1 cup weekly per plant into the topsoil. In areas where the soil is acidic or I add more than 2 cups, which definitely will make the soil too acidic, I have observed blossom-end rot with as much as 40% of the fruit lost!
Soil Amendment Ratios
- 1 cup grounds: Per plant weekly
- Mix with 2 cups compost to buffer acidity
- Never exceed 20% of total soil volume
Acidity Management
- Test pH monthly - ideal range 6.0-6.8
- Add crushed eggshells (1/2 cup) per 5 plants
- Leach soil with water if pH drops below 5.8
Composting Method
- Mix grounds with browns (3:1 ratio)
- Turn pile weekly for aeration
- Age compost 60 days before use
Check the plants for acidity stress. Yellowing leaf edges indicate an imbalance in the pH levels. I have a routine I do every week of testing the soil at 4-inch depth using a meter. If the value falls below 6.0, I add dolomite lime in 1 tablespoon increments per plant and suspend fields for 14 days. Recovery takes 3-4 weeks.
Container gardeners can mix coffee grounds with potting mix at planting time. Here's how I make my coffee-ground potting mix: One part coffee grounds, three parts potting soil, one part perlite. This mix produced 12 Bush Champion cucumbers in five-gallon buckets last season. I flush out both containers once a month, as a preventative measure against salting my plants.
Avoid using fresh coffee grounds, as they will impede seed germination. Instead, I compost the used grounds first. Cold-brew coffee residues work best as they are less acidic. For use as a foliar feed, steep 2 tablespoons of grounds in 1 quart of water overnight, strain, and spray the leaves of the plant leaves at dawn.
Read the full article: How to Grow Cucumbers: Expert Tips for Beginners
