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A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

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Monday - April 21, 2008

From: Atlantic Beach, NY
Region: Northeast
Topic: Soils
Title: Plants for acid soils and coffee grounds for the soil
Answered by: Barbara Medford

QUESTION:

Please tell me what plants & flowers need acid soil and are coffee grains good to make soil acid?

ANSWER:

Once upon a time, people took their used coffee grounds outside to a shady spot and buried them. This encouraged earthworms to show up, because the grounds help to hold moisture in the dirt. Sadly, the people doing this were not doing it for the good earthworms can do for gardens, but for bait! That same principle does hold true, however, when you are preparing potting soil and need some acidity in it. Everybody knows coffee is acidic, and your stomach will remind you of that if you drink too much. So, you recycle the leftover grounds from your morning cuppa into an acid-producing, moisture-holding additive to potting soil. Plants that need an acidic soil to do well are rhododendrons (including azaleas), blueberries and blackberries, hydrangeas and many types of evergreens and conifers. Most other plants, including vegetables and fruits, need a neutral to slightly alkaline soil. Some gardeners who are growing acid-loving plants suggest using the coffee grounds as a side dressing to the plants in the ground.

 

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