My obsession with humongous white hydrangea blooms started many years ago. I was hooked when a vendor at my local farmers market showed up with tall buckets full of monster-sized white hydrangeas. They were a spectacle - their stems were almost as tall as me, and the flowers that topped them were bigger than my head. With their audacity, they sold out in minutes.
I'd never seen such flowers and I inquired with the farmer about the variety and how they grew them. With a twinkle in their eye, they simply wouldn't give up their special secret.
I've been trying to figure it out on my own ever since.
There has been quite a bit of trial and error over many years. But now, I can confidently tell you (with a twinkle in my eye) that it really comes down to one trick (plus a couple less important side tips).
Step by Step: How to Grow Huge Hydrangeas
- My experiments were conducted with Hydrangea paniculata 'Limelight'. Limelight is a panicle hydrangea. This technique will likely work with other panicle hydrangeas or smooth hydrangeas. Both are woody hydrangeas that bloom on new wood. If you want to try this, I would start with Limelight and then move on to other varieties as you get confident. Limelights are tough as nails and it is hard to truly mess them up permanently so you can go forth in confidence that you aren't going to kill them.
- Plant your hydrangeas in good well drained soil. In my experiments, better soil and more regular water does matter to size and will lead to bigger blooms. The size difference is however negligible when compared to the real trick (I'm getting there).
- Let them settle in, establish themselves and grow for a couple seasons.
- Here is the trick - CUT THEM BACK HARD. Very hard. Don't panic, but the trick is to take every branch down to just a few inches above the soil. It is scary, but trust me on this one. Cutting like this is going to make you have a very different plant than what was growing naturally. Generally, Limelight hydrangeas need very little pruning and they will grow to be a large shrub that fills out nicely if they have even sunlight. Once you cut hard, you are not going to have a bushy bush. You will instead have long sticks with pom poms on the ends. I tried this with a shrub to the right of my front door and now it needs to be moved because it kind of looks ridiculous and has a tendency to flop. I will be re-locating it to an area of my garden where things are a little more functional (like the veg/ cutting garden) than beautiful. I love the huge blooms, but they come from an awkward shrub.
- If you plan to do this to a shrub that is part of a border or aesthetic planting scheme, then I reccomend adjusting the surrounding plants. Choose something that will hide the legginess of the shrub and will help to hold up the humongous flower heads to come. Your new hydrangea will send up long stems with a single massive blooms on the end.
So there you have it. Be brave and cut the shrub back - basically to the ground, and as a note of good measure, feed them and water them well. Your reward - blooms that are bigger than a basketball.