TIL a trick for keeping hydrangeas blue from a customer at the farmers market

A regular at the Saturday market in Tacoma told me she adds a tablespoon of aluminum sulfate to her watering can once a month for her potted hydrangeas. I tried it on a test plant in the shop, and after about six weeks, the blooms are noticeably more vibrant. It's a lot cheaper than the branded soil acidifiers I was buying. Has anyone else had good results with this method, or is there a better mix you use?

3 comments

3 Comments

margaretm2311d ago

Ever wonder if the type of water you use matters... like, is your tap water too hard?

tessa_clark7416d ago

Actually had the opposite problem with that method (it burned the roots on a couple of my plants). Coffee grounds worked better for me, just sprinkled on the soil.

ruby45016d ago

Heard coffee grounds can make the soil too acidic for some plants. Might depend on what you're growing.