The marketed Bobo hydrangea height is 2 to 3 feet (60 to 90 centimeters) tall and 3 to 4 feet (90 to 120 centimeters) wide. That's what you'll see on the tag at your garden center. But those numbers only hold true if you prune your plant each year.
So how big does bobo hydrangea get without pruning? The answer might surprise you. Proven Winners user reviews report some unpruned plants reaching up to 6 feet (1.8 meters) after five years. That's double the size on the label. I've seen this happen in my own yard with a Bobo I forgot to trim for two seasons. It shot up past 4 feet before I caught it.
The US Patent gives you the most precise bobo hydrangea size data. Under testing, plants grew about 60 centimeters (24 inches) tall. They spread about 50 centimeters (20 inches) wide. Each plant pushed out around 35 lateral branches. Keep in mind these numbers come from young nursery plants. Your mature garden shrub will grow larger than this over the years.
You should compare Bobo to its relatives to see how small it is. A standard panicle hydrangea grows 8 to 25 feet (2.4 to 7.6 meters) tall per NC State Extension. Bobo is a tiny fraction of that size. Even Limelight hits 6 to 8 feet in most yards. Your Bobo stays much shorter than all of them. It's one of the smallest cultivars you can find in this plant family.
When I first planted my Bobo, I measured it each spring to track growth. In year one, it stayed right at 2 feet tall. By year three without pruning, it had crept up past 3.5 feet. That slow creep is why you need to stay on top of your yearly trim. Your Bobo won't explode in size overnight, but it will inch taller each season if you skip the pruning.
Yearly pruning is the key to keeping your Bobo at that compact 2 to 3 foot range. Cut your stems back by 50% in late winter before new growth starts. I do mine every February and my plants stay right at knee height. Without this annual trim, your shrub adds new growth on top of old wood each year and gets taller and wider over time.
If your Bobo has already grown too tall, don't panic. You can do a hard renewal cut in late winter. Take it down to 6 to 8 inches from the ground. Your plant will regrow from the base because it blooms on new wood. You'll lose one summer of flowers, but you'll get your compact shape back by the following year. Plan your pruning now and your Bobo will stay the small shrub you wanted when you first bought it.
Read the full article: Bobo Hydrangea Care and Growing Guide
