My obsession with huge 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 (I’m 5’10), and the flowers that topped them were bigger than my head—the audacious human-sized flowers sold out in minutes.
Of course, in awe, I immediately started asking questions about the . What variety are they? How did you get such long stems? Where did you grow them? Did you fertilize? What is the magic behind these crazy flowers?
But, with a twinkle in their eye, they simply wouldn’t give up their special secret.
So, I had to start experimenting on my own.
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 of less important side tips).
Step by Step: How to Grow Oversized Huge Hydrangeas
Step 1: Choose the right plants
My experiments were conducted with Hydrangea paniculata ‘Limelight’. Limelight is a panicle hydrangea (paniculata). This technique will likely work with other panicle (also called peegee) hydrangeas or smooth hydrangeas (hydrangea arborescens).
Note: My experiments were with limelight hydrangea, so you may get different results from other cultivars and varieties.
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 very adaptable and easy to grow, 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.
Planting hydrangeas for the biggest possible blooms:
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. I actually suspect that water is more key that soil quality (some of my less successful experiments were on a slope where the water didn’t soak in as much as flatter areas).
It generally isn’t recommended that you spend a lot of effort (or any effort) trying to improve the soil for these plants. You can often create a problem (particularly if you have clay soil) where you create a sink bowl effect. This is where your planting hole soil is very different than the surrounding soil and water doesn’t drain properly. Wet roots and poorly draining soil are the worst things for these plants – the root ball will rot and you may not get any flowers.
The size difference from normal to mega-monster sized – is however negligible when compared to the real trick (I’m getting there).
Don’t work with newly installed plants
After planting your hydrangeas, let them settle in, establish themselves, and grow for a couple of seasons. This will give them time to build resiliency as you start to manipulate them – they need strong root systems so they can deal with the big trick.
How to make HUGE hydrangeas:
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 with even branching structure. (If they have even sunlight).
You need to understand that 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. This is the sacrifice you are making – a nice landscape shrub or a weird looking shrub – but the flowers are at least 6x bigger. And if you took them to a farmers market they might sell out in minutes.
One of my experimental shrubs was adjacent to my front door, and now it needs to be moved because it kind of looks ridiculous (actually kinda ugly) and it has a tendency to flop (those flower heads are so huge they woody stalks almost can’t hold).
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. I’d suggest you keep this in mind when you start experimenting.
If you plan to do this to a shrub that is part of a border or aesthetic planting scheme, then I recommend adjusting the surrounding plants. Choose something that will hide the legginess of the shrub and will help to hold up the giant 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.
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Should you do this to hydrangeas in pots?
I don’t see why not.
I love these too, but when do you cut them back, ????
I cut them back late in the fall – or very early spring. Either has worked for me.
I love your article& have lots of plants this fall & I am going to get them established& do what u sai- I have plants a new bed of He pink hydranger that was chosen for the women who had cancer (my sister lost a breast to cancer but has been cancer free for over 10 years) this bed is or her
I have a bushy bush growing very healthy in a large pot. It has not flowered at all. It has sun in the morning and shade in the afternoon . I am afraid to prune it!!what can I do??
Do you know what kind of hydrangea it is? If you are afraid to prune – do just a bit (maybe 1/3 of a harsh prune) and see what happens. (I suspect it will flower).
I had bo trouble growing these in ny but in north east Texas have never been able to grow them.Any suvgestions?
It is hard for me to say, not knowing anything about your specific conditions. Hydrangeas (depending on variety) can be very sensitive to water – they will be the first to droop and get stressed in hot, dry weather. That said, Limelights (which are the specific variety that were grown for this post) are not so sensitive. I’d suggest talking to a local nursery – they will have much better advice that I can offer from Boston.
Can I move my hydrangea? it’s a strawberry vanilla
Of course you can! – take care to move it when it isn’t super hot (so maybe wait until a little later in the season – fall is good) – and then take care to dig it out with a decent sized root ball and water it in very well. Keep watering at least every few days until winter.