How to Grow Hydrangeas
Beautiful additions to any garden and renowned for their ability to attract pollinators, hydrangeas are among some of the most favored flowers in gardener circles. But they can definitely be a little on the tricky side to grow, especially considering how many variables come into play based on where you live and which variety you’re growing. Check out our gardening guide below for everything you need to know about how to grow hydrangeas and keep them healthy all year round.
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All About Hydrangeas
Technically shrubs, hydrangeas have been widely adapted to various climates and environments, which means you can find them in USDA Plant Hardiness Zones 3 through 9. Mixed with perennial flower borders or planted in mass, hydrangeas make for an excellent focal point in residential gardens.
There are more than 75 species of hydrangeas out there, and they appear in all shapes, sizes and colors. Some are even evergreen while others are deciduous. Understandably, it’s wise to do a little research before planting to make sure you choose the species best suited for your environment and use.
Types of Hydrangeas
You can find hydrangeas in a wide range of varieties and species. But the vast majority you’ll see at nurseries across the country fall into one of three categories: old wood, new wood and everbloomer hydrangeas.
Old Wood Hydrangeas
Old wood hydrangeas bloom on old wood, which means their buds will develop and form in the autumn and flower the following spring and summer. Mophead, or French hydrangeas, as well as Lacecap hydrangeas fall into this category. Avoid pruning these in the autumn, winter and spring. Otherwise, you won’t have any buds or flowers when summertime rolls around. If necessary, you can prune in June or July, but sparingly and only if the plant is out of control or taking over other plants in the garden. You can remove dead stems, flowers and wood at any time of year without harming the plant or hindering new growth.
New Wood Hydrangeas
Can you guess this one? Unlike old wood hydrangeas, which bloom on old wood, new wood hydrangeas bloom on new wood. You can prune these in the autumn and still see new blooms and flowers in the spring. One of the more popular varieties that falls into this category is the Limelight hydrangea, a staggering species on strong stems that is often used as a dramatic hedge.
Everbloomer Hydrangeas
A curious subset of Mopheads bloom on both old and new wood. You can prune them, or you can leave them be – either way, you will see beautiful blossoms as the shrub comes into season. Endless Summer, Summer Crush, and Blushing Bride are among the varieties that fall in this unique and lesser-known category of hydrangeas.
How to Grow Hydrangeas
With varieties ranging from dwarf sizes to ones that tower over even the tallest people, it’s hard to pin down details on how to grow hydrangeas without knowing your specific variety. It’s best to know what variety you have and do your due diligence on that specific species before adding it to your garden. However, a few general rules of thumb apply to almost all hydrangeas:
Plant your hydrangeas in autumn. This gives them ample time to develop healthy roots before extreme temperature swings in winter or summer.
Be mindful of spacing. Some varieties can need as much as 10 feet of space between them in order to mature to their full height and width.
Dig a hole at least twice as wide as the root ball and no deeper than the root ball.
Water generously after planting.
As far as light, soil and water are concerned, the range is wide. Some thrive in full sun while others are content in the shade. Some like acidic soil while others prefer neutral. Researching what your specific variety requires is the best way to set yourself up for success when it comes to growing healthy hydrangeas.
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How to Care for Hydrangeas
Watering Hydrangeas
For at least two years after planting, or during a particularly dry season, make sure to give your hydrangeas at least an inch of water per week (preferably in the morning). Some experts say giving the plants a deep soak at their base multiple times a week is the most efficient way to promote a healthy root system.
If the leaves wither or the soil feels dry to the touch, you might need to increase your watering frequency. Adding a generous layer of mulch around the base of the plant will help the soil stay moist and cool, which will keep your hydrangeas healthier.
Soil and Amendments for Hydrangeas
Hydrangeas planted in soil rich in nutrients, such as high-quality compost, are unlikely to require fertilizer. In fact, too much fertilizer can cause these shrubs to produce more leaves than blooms. If you notice that in your own garden, back off the fertilizer or drop it all together. Better yet, send a soil sample to your local extension office to see what specific nutrients might benefit your plants.
How to Overwinter Hydrangeas
When winter is on the way, you’ll want to tuck your hydrangeas in to protect them from frost. Some gardeners suggest covering them with a minimum of 18 inches of mulch or straw or covering the entire plant.
How to Pick Hydrangeas
Hydrangeas make for elegant and romantic cut flowers, especially when displayed in clusters. If you choose to harvest your hydrangeas, use a sharp, clean pair of garden shears to cut the plant first thing in the morning. Immediately strip the lower leaves on the stem and place it in cold water. Allow the flowers to rest in a cool place away from direct sun for a few hours before recutting the stem at a 45-degree angle and arranging in a vase. If the flowers begin to wilt, soak them in cool water for 10 minutes before placing them back in the vase. This will revive the blooms and extend their vase life.
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Troubleshooting Hydrangea Care FAQs
Why aren’t my hydrangeas blooming?
Make sure your growing conditions are amiable to the plant. You may need to provide more shade or sun or adjust your watering schedule. You’ll also want to double-check your variety. Is it an old or new wood hydrangea? Are you pruning it properly based on when new buds form? Just because the hydrangea isn’t blooming doesn’t mean it is unhealthy; it might just mean you need to experiment with conditions and care in order to see more blooms.
Why are my hydrangeas the wrong color?
Some hydrangea cultivars will change color if you adjust the pH of your soil. It isn’t an instantaneous correction. Be prepared for a few weeks of transition, and only do this with plants that are a minimum of two years old. More often than not, hydrangeas planted in soil with a pH of less than 5.5 produce flowers in blue hues. Soil registering above 6.0 will produce flowers in pink hues.