The day I tested that 'coffee grounds in the garden' tip and killed my hydrangeas

I read this article last month saying used coffee grounds add nitrogen and make soil acidic. So I dumped about 2 cups around each of my 3 hydrangeas in Portland. Within a week the leaves turned yellow and started curling. Turns out fresh grounds are still acidic enough to burn roots. I found a soil test kit at Home Depot for $12 and my pH was down to 4.5. Anyone else kill a plant trying to be eco-friendly?

3 comments

3 Comments

david_reed2217h ago

Hold on, I gotta push back a little here. You dumped 2 cups of fresh grounds around each plant, that's a ton of nitrogen all at once, of course it burned them. I use coffee grounds all the time in my garden but only a thin layer mixed into compost or let them dry out first for a few weeks. Plus hydrangeas actually want a slightly acidic soil around 5.5-6.0 for that blue color, not 4.5. The tip isn't wrong, you just went way overboard with the amount and skipped the simple step of letting them break down first.

kai_burns7316h agoTop Commenter

Ngl @david_reed22, I read coffee grounds need to age a bit first to avoid burning plants.

grant15512h ago

Piling on fresh grounds like that is a rough lesson, @kai_burns73. Ive done the same thing with compost and learned the hard way that a little patience goes a long way.