Do blueberries need coffee grounds?

Blueberries need coffee grounds only as a way to supplement soil acidity, and not used on its own. Fresh grounds can mold and will damage roots and only acidify while they are fresh. I learned this with my plants' yellowing from having used grounds without composting it first. It is important to use grounds with elemental sulfur to get a reliable pH lower than 5.5.

Constant use of coffee grounds leads to nitrogen imbalances. I had bushes that became stunted because I was applying them at 2 cups per week. It browned the edges of the leaves. I now limit coffee grounds to monthly applications. Get a soil pH test every 3 months with a $15 meter or similar to test for declines in pH. And coffee grounds alone will not remediate alkaline soil.

For serious pH issues, do not use ground products. Instead, for each shrub, dig in 1 cup of elemental sulfur to a depth of 6 inches. Water thoroughly. Elemental sulfur has a slow starting action, I had to wait 4 months after applying it to go from a garden pH of 6.8 to 5.3. During this correction process, be sure to retest the soil every 6 weeks.

Container growers are the ones who receive the most benefit from this. Mixing one part composted coffee grounds into five parts peat-based soil generally works well. Just be sure you monitor drainage as coffee grounds hold moisture. I planted my potted Bluecrop in 25% less sulfur as a result of this blend. If you are planting directly in the ground, consider sulfur and pine bark before the grounds.

Read the full article: How to Grow Blueberries: 7 Essential Steps for Success