Hydrangeas: When to Prune & How To Bloom

Even just planting hydrangeas will have your garden dressed to impress as they amaze you with their style. These gorgeous blooms are a popular choice for good reason – they’re straightforward to care for, they thrive in an array of conditions, and their blooms just can’t be competed with. They’re stylish in a single tone, with color choices from blue, to pink, to white and options in between, and some are even able to bloom in a variety of colors on a single plant. 

Hydrangeas are already versatile and gorgeous, but knowing all of the tricks for how to maintain them best here in Iowa will have you pruning your way to the best hydrangeas on the block.

(Photo courtesy of NetPS Plant Finder)

Hydrangea Care

Thankfully, hydrangeas are beautiful even when they aren’t blooming, with elegant foliage that compliments the landscape around them. As great as their lovely leaves are, everyone knows that the main event for these popular plants is their stunning blooms. Knowing how to best care for them will provide your garden with better blooms every season. 

Although these flowers are versatile and can grow in many of our Iowa conditions, you’ll have the best results if they’re planted in moist, rich soil that has good drainage. Consider using compost to enrich the soil with more nutrients when planting, and each spring afterwards. Using mulch around the base of the plant is a great way to retain moisture at a more consistent level, all while preventing weeds from sprouting and ruining the visual effect. 

Choose a location for your hydrangeas that gets plenty of sun in the morning and is shaded from the afternoon heat. We suggest planting them close to larger trees as a great way to ensure the right sun exposure as well as protection from our desiccating prairie winds.

(Photo courtesy of NetPS Plant Finder)

How to Prune Hydrangeas

Producing the best hydrangea blooms mostly comes down to proper pruning techniques. As the blooms for each season are set, you’ll need to be careful not to snip them off while you’re trimming, or you’ll have a year of lovely foliage but not much else. 

Pruning correctly relies on knowing where the buds set. With most species, like Bigleaf, Endless Summer, or Oakleaf, the new buds bloom on last year’s stems—also known as old wood. This is important to keep in mind so that you don’t clip them off when pruning. Old wood hydrangeas tend to bloom in the early summer. To prevent snipping away all of the best blooms for next year, prune old wood hydrangeas immediately after blooming ends in the summer. That will ensure that you can prune back the hydrangea without endangering new buds that will simply set on the wood remaining after pruning. 

Some hydrangeas, however, bloom on new wood, or the new spring growth. For these hydrangeas, like the Panicle hydrangea, pruning is simple, and you can snip back the shrub in the fall or early spring while the plant is dormant, before the buds are set. 

To simplify, check the label of your hydrangea when you plant to see what type it is to guide your pruning decisions.
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(Photo courtesy of NetPS Plant Finder)

Blooming Hydrangeas

Pruning is the most important factor in having gorgeous hydrangea blooms, but there are a few other factors that you can control to make sure that yours are the best of the best:

• Keep the foliage clean and dry. Hydrangeas are prone to leaf fungus, which not only ruins the look of your plant but can weaken it and affect its ability to bloom to its full potential. Water your hydrangeas close to the ground to prevent muddy water from splattering the leaves, especially in cooler weather when fungus can thrive.
• Concentrate your trimming on removing the oldest parts of the plant that produce weak flowers. Consider pruning aggressively to get the biggest flowers, but keep in mind that moderate pruning is the best way to have decent blooms on sturdy stems and avoiding a floppy appearance.
• Choose the right fertilizer. Excessive fertilizing can result in a busy hydrangea with limited blooms. Stick to a 10-10-10 fertilizer for the healthiest plant with gorgeous flowers. Make sure to consult a team member if you’re not familiar with fertilizer formulas—the best fertilizers for houseplants won’t necessarily be ideal for your hydrangeas
• Alter soil pH to manipulate the bloom color. Some hydrangeas can change the color of their blooms between pink and blue—though it’s usually easier to change from pink to blue instead of the other way around. Improve the tone of your alkaline-preferring pink blooms by boosting the soil pH with lime and fertilizers high in phosphorus. To change from pink to blue, you’ll need more acidic soil, which you can achieve by adding aluminum sulphate to the soil. The shade of blue you get with this color change is ethereal and stunning, and a rare color in the garden that is worth cultivating. 

Hydrangeas are a gift to our gardens with their heaps of blooms every year, and solving how to take care of them is easy once you know how to prune them. There are so many great choices when it comes to the perfect hydrangea for your home—it all comes down to what style and type of bloom is your favorite to enjoy.