Q: I have a common question concerning my hydrangeas blooming pink instead of blue. I purchased them while they were blooming and they were blue.
I know it is all about the soil — acid for blue blooms — I have watered them with aluminum sulfate — and they continue to bloom light pink.
Question 1 — Am I using the correct product — if so, how often do I water with this and when do I begin?
Quesion 2 — When do I prune my hydrangeas so I can be assured of blooms the following year?
Thanks for you time and I look forward to hearing from you.
A: Hi Lavonda,
Because your hydrangeas were blooming blue when you bought them and have now turned pink, I would guess you have somewhat alkaline soil. Making the soil acid will take time. You probably won’t see a difference this year. Repeat the applications of aluminum sulfate a couple of more times, but don’t overdo it, because too much aluminum in the soil isn’t good for plants. You could also apply garden sulfur to the soil surface around your plants and water it in. And if you’re a ground coffee drinker, save the grounds and spread them on the soil around your plants to acidify it. Once your hydrangeas start blooming blue, you may have to repeat the application of sulfur every couple of years to keep them that way.
As for pruning, for most varieties, the rule is prune them immediately after their flowers fade. This is because most bloom on growth made the previous year. So if you prune them in fall, winter, or spring, you’ll cut off the flower buds. However, a few types, such as ‘Endless Summer,’ ‘All Summer Beauty,’ and ‘Penny Mac,’ bloom on both last year’s growth and new growth. So even if you prune them to the ground in winter, you’ll still get blooms.
Shout-Out to Readers: What trick do you use to turn hydrangeas blue or pink? Be nice and tell us.