How to Grow and Care for Hydrangeas

BY Jolene hansen

Woven through gardens and bouquets, hydrangeas have little competition when it comes to bold, lush blooms. There's something about their enduring beauty that completes our gardens and homes. Growing garden hydrangeas isn't hard when you understand their needs. Follow these simple hydrangea how-tos and fill your garden with these flowering beauties:

How to Choose a Hydrangea

Browse through plant catalogs online and the hydrangea options seem endless. Plant explorers keep discovering them, and plant breeders keep developing new varieties. But most U.S. garden hydrangeas fall into one of these categories:

  • Bigleaf, known by the botanical name Hydrangea macrophylla, won gardeners' hearts with huge blue and pink "mophead" blooms. New varieties range from white to blush to vibrant blue, purple, pink and nearly red. Some bigleaf types offer delicate "lacecap" flowers instead.
  • Panicle or grandiflora (Hydrangea paniculata) has large, showy pyramidal flower clusters that run from pink-tipped whites to bright strawberry and lime green. This hardy group is especially good for northern gardeners.
  • Smooth (Hydrangea arborescens) and its softball-like white flowers have been favorites for decades. Modern varieties of this North American native come in cream, lime, blush and mauve.
  • Oakleaf (Hydrangea quercifolia), also a North American native, has oak-like leaves that turn burgundy-bronze in fall. Its cone-shaped blooms run from white to deep rusty rose.
  • Mountain (Hydrangea serrata) has blooms similar to bigleaf but smaller. From white to vivid purples, the flowers may be lacecaps or mopheads.

Each hydrangea type offers numerous options, but pay attention to mature size. Many new varieties are designed for small spaces, and they stay just 2 to 3 feet tall and wide. But other hydrangeas can reach 20 feet tall or more. Always choose varieties that will still fit their planting site when they mature.

 Long, pyramidal flower clusters mark panicle hydrangea stems.

How to Plant a Hydrangea

The best time to plant hydrangeas depends on where you live. If you have cold winters, plant hydrangeas in early fall — well before winter comes — or wait until spring. If you have warm winters, fall planting ensures hydrangeas establish well before summer heat. Hydrangeas flourish in light shade, but abundant blooms and strong stems depend on sun. Ideal planting sites combine four to six hours of morning sun with late-afternoon shade. In northern areas with less intense sun, hydrangeas need less shade. In southern zones, they need more. Hydrangeas prefer moist, well-drained soil. Adding organic matter and garden gypsum can help loosen heavy clay. With some hydrangeas, soil pH influences flower color. Acidic soil turns bigleaf blooms bluer, while alkaline soil turns them pink. Your natural soil may trigger shades of purples, pinks and blues unique to it and you. Keep your hydrangea in its nursery pot while you dig, so roots stay protected. Dig a hole slightly more shallow than the pot's depth, but two to three times as wide. Remove the pot, and center the rootball in the hole. It should sit barely above the surrounding soil. Hydrangeas have shallow roots, so don't plant too deep. Add soil back underneath if needed. Once you're satisfied, fill the hole halfway with soil. Water thoroughly, and treat your plant with Pennington UltraGreen Plant Starter with Vitamin B1 to reduce transplant shock. Incorporate Pennington UltraGreen All Purpose Plant Food 10-10-10 in the soil to help give your plant a solid nutritional foundation. Then finish backfilling the hole, and water thoroughly. Add a 1- to 2-inch layer of mulch, such as compost or pine straw, to help protect roots and retain soil moisture.

The creamy blooms of smooth hydrangeas are old-fashioned favorites.

How to Care for Hydrangeas

You may notice the words "hydrangea" and "hydrate" have a lot in common. Proper hydration is essential for hydrangea success. To avoid yellow, brown or curling hydrangea leaves, keep the soil consistently moist — never overly wet or dried out.

That means more watering during hot temps and low rainfall, especially during your hydrangea's first few years in your garden.

Regular feeding through the growing season helps ensure peak hydrangea beauty. One application of Pennington UltraGreen Color Blooms & Bulbs Plant Food 15-10-10 feeds your plant for up to four months and encourages bigger, more abundant flowers.

Hydrangeas can be prone to fungal leaf diseases that cause dark black or brown leaf spots, white spots or even holes in leaves. With fungal diseases, prevention is key. Stop, control and prevent hydrangea diseases such as leaf spot and rust with Daconil Fungicide, available in convenient ready-to-use and concentrate forms.

Some hydrangea leaf holes come from unwelcome insects. To protect your hydrangeas against pests, including Japanese beetles, turn to Sevin Insect Killer Ready to Use2 for spot treating individual plants and smaller garden areas. For larger areas, turn to Sevin Insect Killer Concentrate or Sevin Insect Killer Ready-to-Spray.

With Sevin Sulfur Dust, used as a dust or a spray, you can treat hydrangeas for leaf spot, botrytis blight, powdery mildew and red spider mites, all with one product.

Oakleaf hydrangea's fall leaf color is a garden lover's dream.

How to Prune Your Hydrangea

Timing is everything with hydrangea pruning. Panicle and smooth hydrangeas flower in summer on new spring stems — what's called "new wood." Cut back panicle hydrangeas by one-half right before spring growth starts. Cut smooth hydrangeas back to about 18 inches at the same time. The pruning encourages more new stems and that means more flowers. All other hydrangeas bloom in late spring to early summer on what's called "old wood" — the stems left from the previous year. Prune these types right after they finish blooming. Wait too long and you'll sacrifice next year's flowers. Some hydrangeas bloom heavily on old stems and then have a second round of summer flowers on new stems. These "remontant" bloomers do best with little or no pruning. Cut out dead or damaged stems at any time. Pruning time is a great time to take cuttings and start new hydrangea plants. Hydrangeas are easy to root and propagate, so double your fun — and your plants — when you prune.

Mountain hydrangea's delicate lacecap flowers delight.

How to Make Hydrangea Flowers Last

Many gardeners let hydrangea flowers stay on the plant all winter. But fresh-cut blossoms and dried hydrangea flowers make gorgeous indoor arrangements, too. To make fresh-cut hydrangeas last as long as possible, wait until blooms mature fully and petals have a papery look. The older the flowers, the longer they'll last.

Plan your harvest for early morning, before flowers get dehydrated and warmed by sun. Take a bucket of warm water, so cut stems can go in water immediately. Back inside, prep your vase and remove any remaining leaves. Run several inches of water in a sink or bowl, and recut the stems underwater to eliminate any water-blocking air bubbles. Place your vase in a cool spot out of direct sun to maximize your flowers' vase life.

For dried arrangements, wreaths and similar projects, you can let hydrangea flowers age on the plant to shades of antique green and pink, and then harvest your dried blooms. To expedite the process, harvest flowers once they start to age. Then hang them upside down in a cool, dark spot to dry.

Garden hydrangeas will bring you and your family years of beauty and bouquets, whatever types of hydrangeas you choose to grow. At GardenTech, we want to help you grow and enjoy beautiful and productive hydrangeas, vegetables, fruits and flowers. You name it. We're here for you.

Always read product labels thoroughly and follow instructions, including guidelines for listed plants and pests.

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