How to Grow Hydrangeas
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How to grow hydrangeas starts with knowing which hydrangea you have, because the type decides the light, the pruning and whether the flowers form on old wood or new. Extension pages from Clemson, Massachusetts, New York and California agree on the basics: moist, well-drained soil full of organic matter, shelter from hot afternoon sun, and steady water.
They part ways on pruning dates, pH cutoffs and fertilizer timing. This guide reports each figure with its source, so you can see where the answer changes.
Quick answer
- Identify the type first. Bigleaf hydrangeas bloom on old wood, while smooth and panicle types bloom on new growth.
- Give moist, well-drained, organic soil and about an inch of water a week, more in hot, dry weather.
- For blue bigleaf flowers, keep the soil acidic. Clemson targets a pH of 5.0 to 5.5, while pink flowers need a higher pH.
- Prune by type and timing. Clemson advises against cutting bigleaf stems after August 1, while Cornell says later fall pruning is harmful.
Start with the type you are growing
Most gardens hold a handful of types, and the sources describe them differently. Massachusetts extension lists bigleaf hydrangea at three to six feet tall with an equal spread, and says it blooms in summer on mature wood. Clemson gives the bigleaf range as four to 12 feet, depending on the variety. Smooth hydrangea is a rounded, understory shrub that prefers part shade and white summer flowers. Panicle hydrangea can reach 10 to 20 feet and blooms from July into September. Oakleaf hydrangea is native to the southeastern United States, grows to about eight feet, and has large lobed leaves. Climbing hydrangea is a slow-growing vine that clings to walls and other surfaces with root-like holdfasts.
Size and habit vary widely. Massachusetts gives smooth hydrangea a rounded form three to five feet high and wide, and says the cultivar ‘Annabelle’ can carry flower heads up to 12 inches across. Oakleaf forms a slowly widening clump by sending up stems from the roots, and its bark turns shaggy and reddish with age.
Cornell Cooperative Extension in Orange County notes that six types are common in home landscapes, and that many need different pruning. Massachusetts says climbing hydrangea has the same growing needs as other hydrangeas but is slow to establish, and that once it is settled it may climb to 60 feet. Cornell says it needs little or no pruning. Knowing your type is the single step that changes the rest of the care plan.
Light: morning sun and afternoon shade
The sources agree that afternoon shade is the safe default. Clemson describes bigleaf hydrangea as best with morning sun and afternoon shade, and says to avoid hot, exposed sites. The Massachusetts page says hydrangeas can take full sun or light dappled shade, but bigleaf hydrangea may wilt in full sun even when the soil is moist. The UC Integrated Pest Management page says hydrangeas do well in full sun, but need partial shade in very hot climates.
Other types differ. Cornell says the right exposure depends on the cultivar, and that smooth hydrangea prefers morning sun and afternoon shade. It also says panicle hydrangea ‘Grandiflora’ tolerates full sun, and that mountain hydrangea does best in slight shade. Cornell also describes mountain hydrangea as more drought tolerant.
Soil, pH and flower color
Soil should be moist, well drained and rich in organic matter. The Massachusetts page advises compost or well-aged manure, and says hydrangeas will not thrive in very dry, sandy soil. Cornell gives the same basic recipe and suggests mulching with two to three inches of bark or other organic mulch. The UC page says hydrangeas need rich, porous soil and are sensitive to soil type.
Flower color is where the pH matters. Clemson says bigleaf flower color is set indirectly by soil pH, which controls how much aluminum is available to the plant. It gives pH 5.0 to 5.5 for blue flowers and 6.0 or higher for pink. Massachusetts places the line differently, saying soil at pH 5.5 and below gives blue flowers, and pH 6.5 and above gives pink, rose or red, depending on the cultivar. Cornell says acid soil gives blue and alkaline soil gives pink.
Clemson advises a soil test every two to three years, and says to test before applying sulfur or lime. For blue flowers it suggests sulfur or aluminum sulfate in April, when new growth emerges, and for pink it suggests lime. Its advice is to test first, because over-correcting is easy. A guide to soil test kits can help you choose a tester before you change the pH.
Planting and mulch
Spring or fall is the best time to plant, according to Clemson. Dig a hole two to three times as wide as the root ball, but no deeper than the root ball is tall. Massachusetts asks for the same depth as the nursery pot, with the top of the root ball level with the soil. Before planting, check container-grown roots and loosen any that circle the pot.
Mulch the surface. Clemson and Massachusetts both recommend two to three inches of organic mulch. Massachusetts adds a caution: keep the mulch spread over the roots but off the crown of the plant. Cornell gives the same two to three inch range, using bark or another organic mulch to hold in moisture.
Containers are a practical option. Clemson lists containers on patios and terraces among the uses for bigleaf, alongside foundation plantings, borders and mass plantings. The UC page says hydrangeas are often grown in containers and need a regular supply of water, which fits the watering advice that follows.
Water deeply and steadily
Massachusetts gives the working rule: about an inch of water a week, applied as a deep soaking. In very hot, dry weather, the same page says, hydrangeas may need up to two inches a week to keep from wilting. Clemson says to water deeply once a week, or more often in dry conditions, and reports that in South Carolina summer heat, sandy soils may need deep watering twice a week.
Drip irrigation or soaker hoses work well, the Massachusetts page says, because they keep the soil moist while leaving the foliage dry. For ideas on checking moisture before you water, see our soil moisture meter roundup.
Feeding without too much nitrogen
The two extension pages give different schedules. Clemson recommends a balanced fertilizer such as 10-10-10, applied at two cups per 100 square feet in March, May and July, then watered in right away. It says the mulch does not need to be removed first. Massachusetts suggests about four ounces of a balanced fertilizer in early spring and again after flowering.
Both pages warn about excess. Clemson lists excess nitrogen fertilizer among the reasons a hydrangea fails to bloom, along with too much shade and poor soil fertility. Clemson says regular light feeding promotes strong stems, vibrant blooms and consistent color.
Pruning by type and timing
Pruning depends on where the plant flowers. Bigleaf hydrangeas set next year’s buds on mature stems in summer, so cutting them at the wrong time removes the flowers. The table gathers the timing each source gives for common types.
| Type | Where it flowers | Pruning timing the sources give | Source |
|---|---|---|---|
| Bigleaf (Hydrangea macrophylla) | Old wood | Right after flowering; avoid after August 1 (Clemson). Cornell says pruning after September is harmful. | Clemson, Cornell |
| Smooth (H. arborescens) | New growth | Late winter or early spring; can be cut to ground level each year | Cornell |
| Panicle ‘Grandiflora’ (H. paniculata) | New branches | Late winter or early spring, cutting back last season’s growth | Cornell |
| Oakleaf (H. quercifolia) | Old wood | After flowering; in early spring remove weak or winter-damaged stems | Cornell |
| Mountain (H. serrata) | Mostly old wood | Immediately after bloom | Cornell |
For a young bigleaf, Massachusetts says to deadhead spent flowers for the first few years. Once the plant matures, it advises removing the oldest stems, three years or more, right to the ground in late winter. Clemson recommends clean, sharp bypass pruners, and disinfecting them between cuts.
Reblooming bigleaf cultivars change the picture. Massachusetts names ‘Endless Summer’, ‘Penny Mac’ and ‘Dooley’ as types that can bloom on new wood as well as old. Cornell lists ‘Endless Summer’, ‘Blushing Bride’, ‘Red Sensation’ and ‘Double Pink’ as cultivars that rebloom on the current season’s growth when faded blooms are removed.
Winter injury and why blooms fail
Winter damage is the most common reason hydrangeas do not flower, Clemson says. Massachusetts explains the mechanism: winter temperatures below 10 degrees Fahrenheit, along with early-fall and late-spring freezes, can kill all the flower buds, so there is little bloom the next summer. Cornell says bigleaf and mountain hydrangeas are most likely to suffer frost damage to buds. Massachusetts rates bigleaf hydrangea as hardy to zone 6.
Oakleaf hydrangea needs a sheltered spot and winter protection while it is young, according to Cornell. Massachusetts notes that bigleaf may die back to the ground in cold winters.
Propagation by layering and division
Clemson describes two easy methods. For layering, dig a shallow trench beside the parent plant, bend a flexible limb into it, and remove a one-inch ring of bark where the stem is buried. Cover the buried section with soil and leave six to 12 inches of tip growth exposed. For division, use a shovel in early spring to split an old, established clump into smaller plants.
What we could not verify
What the sources do not say
The sources do not agree on several points, and this guide does not pick a winner. Clemson puts the bigleaf pruning cutoff at August 1, while Cornell says pruning after September is harmful. The pH cutoff for pink flowers is 6.0 in Clemson and 6.5 in Massachusetts. The fertilizer schedules differ in both timing and amount. The bigleaf height range differs too, 3 to 6 feet in Massachusetts and 4 to 12 feet in Clemson. The Clemson factsheet is written for South Carolina and the Cornell PDF for New York, so local frost dates and summer heat may change the advice. The pages also name fungal leaf spots and insect pests, but we did not include any control steps, because those belong on product labels and with local extension advice. Nothing in this guide is a product claim.
How we chose
We limited the guide to university and state extension pages that describe hydrangeas grown in a garden. We opened six pages that returned HTTP 200. Four gave usable culture information, and we relied on them. The other two were a University of Florida page that opened to an unrelated department description, and a Virginia Tech catalog record with no growing text. A University of Georgia publication returned HTTP 403, and a Mississippi State page returned HTTP 404, so neither counts. Where the sources disagree, we report both answers. We recommend no products.
Frequently asked questions
Why won’t my hydrangea bloom?
Winter injury is the most common cause, according to Clemson. Too much shade, poor soil fertility and excess nitrogen can also stop flowering. Massachusetts adds that cold below 10 degrees Fahrenheit can kill the flower buds on bigleaf stems. Clemson adds that pruning bigleaf after August 1 removes next year’s buds.
How can hydrangeas get blue flowers?
For bigleaf hydrangea, Clemson recommends soil at pH 5.0 to 5.5, and says to test before adjusting it. Massachusetts places the blue range at pH 5.5 and below. Cornell says acid soil gives blue flowers. The Clemson page suggests sulfur or aluminum sulfate in April, but the Massachusetts page does not give an amendment.
When should hydrangeas be pruned?
It depends on the type. Bigleaf is pruned after flowering and before August 1, according to Clemson. Smooth and PeeGee panicle types are pruned in late winter or early spring, and oakleaf after flowering. The table above gives the timing each source uses.
How much water do hydrangeas need?
Massachusetts recommends about an inch a week in a deep soaking, and up to two inches in very hot, dry weather. Clemson says to water deeply once a week or more often in dry conditions. Drip irrigation or soaker hoses keep the soil moist and the foliage dry.
Do hydrangeas need full sun?
Most do not need full sun. Massachusetts says hydrangeas can take full sun or light shade, but bigleaf may wilt in full sun even with moist soil. Clemson recommends morning sun with afternoon shade for bigleaf, and Cornell says the right exposure depends on the cultivar.
Sources
- https://hgic.clemson.edu/factsheet/hydrangea/ (opened 2026-10-23): Clemson Extension, HGIC 1067, Hydrangea Care in South Carolina
- https://www.umass.edu/agriculture-food-environment/landscape/fact-sheets/growing-hydrangeas (opened 2026-10-23): UMass Amherst CAFE, Growing Hydrangeas
- https://dlc.cce.cornell.edu/pluginfile.php/376773/mod_resource/content/1/Hydrangeas%20-%20Types%20and%20How%20to%20Prune.pdf (opened 2026-10-23): Cornell Cooperative Extension, Orange County, Hydrangeas: Types and How to Prune
- https://ipm.ucanr.edu/PMG/GARDEN/PLANTS/hydrangea.html (opened 2026-10-23): UC Statewide IPM Program, Hydrangea (cultural notes only)
