Separate the myths from the facts regarding this trendy garden practice.
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Creative gardeners are always looking for ways to boost production.
One topic that gets a lot of buzz in garden forums is usingcoffee groundsto fertilize plants.
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Learn how to effectively incorporate coffee grounds into your gardening routine tosupplement tomatoesand other garden plants.
Acidity
First, it is important to understand the differing acidity levels of coffee and coffee by-products.
Organic Nutrients
Spent coffee grounds can contribute to healthy soils by adding organic matter and nutrients.
In the meantime, coffee grounds will not provide an immediate effect on tomato plants.
As such, coffee grounds are best used in compost as a soil builder.
It improves soil structure, allowing air and water to move readily, while enhancing drainage and water-holding capacity.
Compost releases nutrients slowly over time, feeding plants and beneficial soil microbes alike.
One study showed coffee grounds applied to tomato plants as part of a compost mix suppressed common fungal pests.
This research was conducted under controlled conditions and results in the garden setting have yet to be studied.
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This is a case where the potential drawbacks outweigh the known benefits.
Like anymulch material, coffee grounds can help retain soil moisture and moderate soil temperatures.
Further research is needed to compare the pros and cons of top-dressing tomato plants with coffee grounds.
Until more is known, it is best to limit such applications.
Research demonstrates the single best approach is to add coffee grounds tothe compost pileor tumbler.
Apply finished compost to the garden to provide supplemental nutrients as well as organic matter.
Allow coffee grounds to cool before adding them to your compost.
Paper filters will also decompose in the compost pile.
For new garden beds, you might increase the amount of compost to 3- to 4-inches.
Remember, compost alone will not provide all the nutrition tomatoes require for growth and production.
Likewise, do not rely on composted coffee grounds to alter soil pH.
Top Dressing / Mulching
Top dressing with fresh (uncomposted) coffee grounds is not recommended.
Additionally, coffee grounds should not be used in seed-starting mixes as they may inhibit germination.
Rake grounds into the upper soil layer to avoid creating an impenetrable mat on the soil surface.
How To Use Traditional Fertilizers
Tomatoesthrive in loamy soils with good drainage and high organic matter content.
When preparing soil for tomatoes, work in 2 to 3 pounds of complete fertilizer (e.g.
Tomato Care Tips
Frequently Asked Questions
Yes, however this practice is not recommended.
Composting is a far superior way to use coffee grounds in the garden.
Apply composted coffee grounds once per year to planting beds.
Pokorny K.Used appropriately, coffee grounds improve soil and kill slugs.Oregon State University Newsroom.
Published Jun 23, 2023.
Burwell A, Chatrchyan E, and Loomis Z.Mulching with Coffee Grounds.
Cornell College of Agriculture and Life Sciences.
