Hydrangeas are beautiful flowering shrubs that can add lovely pops of color to any outdoor space. With their lush blooms and easy care requirements, it’s no wonder they are so popular. But like any plant, hydrangeas have specific needs to help them thrive. By understanding what hydrangeas require and providing the right growing conditions, you can enjoy their stunning blossoms year after year.
What are the best conditions for hydrangea growth?
Hydrangeas do best in sites with morning sun and afternoon shade. Too much hot sun, especially in the afternoon, can cause the blooms to fade and dry out. Dappled sunlight filtering through trees is ideal. Hydrangeas also require moist, well-drained soil that is rich in organic matter. The soil should hold moisture but not get waterlogged. Most hydrangeas prefer a soil pH between 5.5-6.5, though some can tolerate more alkaline soils up to pH 7.5.
How much water do hydrangeas need?
Hydrangeas have a relatively high water requirement, especially when grown in containers. The soil should be kept evenly moist but not soggy. Water thoroughly until the soil is fully saturated. Container plants may need watering daily in hot weather. Established shrubs in the ground usually only need supplemental water during prolonged dry spells. Use a soaker hose or drip irrigation to target the roots. Avoid overhead watering which can promote fungal diseases. Drooping leaves are a sign plants need more water.
What type of fertilizer should be used?
Most hydrangeas do best with a balanced fertilizer applied in early spring, mid-summer, and fall. Look for a fertilizer labeled for acid-loving plants that contains equal amounts of nitrogen, phosphorus, and potassium such as 10-10-10. Apply according to label directions. Organic options like compost and compost tea can also provide nutrients. Avoid high nitrogen fertilizers which can promote leafy growth over flowers.
How should hydrangeas be pruned?
Pruning requirements depend on the type of hydrangea:
Bigleaf and Oakleaf
These types bloom on old wood formed in the previous growing season. Prune immediately after flowering by removing only spent blooms. Do not cut back further into old wood or the following season’s flower buds will be removed.
Panicle
Panicle hydrangeas bloom on new wood formed in the current season. Prune in late winter or early spring before new growth emerges. Cut back all stems to just above a healthy set of buds. This encourages abundant new growth for flowering.
Climbing
Trim out dead stems and thin congested growth. Otherwise limit pruning to control size and shape. Cut back wayward stems to just above a healthy bud.
Smooth
Smooth hydrangeas bloom on both old and new wood. Do light renewal pruning in spring by removing up to one-third of the oldest, tallest stems down to the base. This stimulates new growth.
| Hydrangea Type | Pruning Time | Pruning Method |
|---|---|---|
| Bigleaf | After flowering | Remove spent blooms only |
| Oakleaf | After flowering | Remove spent blooms only |
| Panicle | Late winter/early spring | Cut back stems to buds |
| Climbing | As needed | Thin and shape |
| Smooth | Spring | Remove 1/3 oldest stems |
Should hydrangeas be deadheaded?
Deadheading, or removing spent blooms, is recommended for most hydrangeas. It not only keeps plants looking tidy but encourages more blooms. For mophead and lacecap types, deadhead back to the first set of healthy leaves beneath the faded flowers. For panicle hydrangeas, cut back the entire flower cluster to a healthy bud at its base. Always make cuts above an outward facing bud to ensure flowers grow in the right direction.
How can hydrangeas be protected in winter?
Hydrangeas grown in colder climates may benefit from extra winter protection. The time to prepare plants is in late fall before the ground has fully frozen:
– Add a 4-6 inch thick insulating mulch of shredded leaves, straw, or pine needles around the base to prevent freeze/thaw cycles from heaving plants up from the soil. Pull mulch away from the stem.
– Wrap or cover the stems with burlap or other material to protect from drying winds. Some gardeners constructed simple wooden frames around plants.
– Burlap screens can provide shade if bright winter sun reflects off snow onto shrubs. Stake the screens into the ground on the sun-facing side.
– Container grown plants should be moved into an unheated garage or cellar for winter. Keep watered sparingly.
– Newly planted and less hardy hydrangeas benefit from a layer of straw or pine boughs over the entire plant. Stake boughs to prevent wind damage.
What causes hydrangea leaves to turn yellow?
There are several possible causes for yellowing hydrangea leaves:
– **Insufficient water** – Drought stress causes leaves to wilt and yellow. Ensure plants receive about 1-2 inches of water per week from rain or supplemental irrigation.
– **Overwatering** – Too much moisture deprives roots of oxygen. Allow soil to partially dry between waterings.
– **Poor drainage** – Waterlogged roots are unable to take up nutrients. Grow in well-draining soil or improve drainage.
– **Root damage** – Construction, tilling, or transplant shock can damage roots leading to yellowing. Avoid wounding roots when planting and dig wide holes.
– **Improper pH** – Extremely acidic or alkaline soils can induce iron chlorosis causing yellowing between leaf veins. Test soil and amend pH if needed.
– **Nutrient deficiencies** – Lack of nitrogen, iron, manganese, or magnesium can cause leaves to turn yellow. Have soil tested and fertilize accordingly.
– **Cold damage** – Early fall freezes can damage leaves and cause yellowing. Protect plants from early frost. Prune out dead growth in spring.
Why do hydrangea flowers turn different colors?
The flower color of some hydrangeas depends on the soil pH. Here’s what affects their color:
– **Pink or Blue** – The most iconic hydrangea color change happens with bigleaf and lacecap types. Acidic soil below pH 5.5 causes them to turn blue. Alkaline soil pH 6.5-7.0 shifts flowers to pink or red shades. More purple blooms develop in neutral pH around 6.0.
– **Aluminum** – The availability of aluminum in the soil is what actually triggers hydrangea flower color change. Aluminum is more soluble in acidic soils and gets taken up by the plants. It reacts with pigments in the flowers to turn them blue.
– **pH affecting uptake** – At higher pH, aluminum becomes unavailable for uptake. Without aluminum, the flowers remain pink due to the presence of other pigments. To shift flower color, alter the pH.
– **Exceptions** – Some hydrangea varieties have been bred to stay a certain color regardless of pH. Also, panicle and oakleaf hydrangeas produce white flowers that are unaffected by pH.
How can hydrangea flower color be changed?
Here are some methods to shift hydrangea flower color by modifying soil pH:
– To make pink flowers turn blue, lower pH by applying aluminum sulfate or elemental sulfur. Work into soil around plants. It may take a couple seasons to see results.
– To turn blue blooms back to pink, incorporate lime or wood ashes to raise pH. Rinse lime off foliage to avoid damage.
– For more precision, use a pH meter to track soil changes. Shoot for pH 5.2-5.5 for blue and 6.2-6.7 for pink.
– Adjust pH gradually in increments of no more than 0.5-1 point per application. Drastic quick changes can shock plants.
– Consider switching out plants instead of trying to drastically alter existing soil pH. Choose naturally pink or blue varieties best suited to your native pH.
– Container grown plants can be moved to a different type of potting mix to easily manipulate the pH as needed.
What causes hydrangea leaves to curl?
There are a few possible causes for curling hydrangea leaves:
– **Cold damage** – Early fall or late spring frosts can damage leaf tissue causing curling. Protect plants from extreme temperature swings.
– **Pest infestations** – Insects that suck plant sap like aphids, spider mites, or leafhoppers cause leaves to distort and curl inward. Check undersides of leaves and treat any pests found.
– **Fungal diseases** – Foliar diseases like powdery mildew cause leaves to shrivel and curl up. Improve air circulation and treat with fungicides if needed.
– **Underwatering** – Lack of adequate water causes dehydration, forcing leaves to curl in an effort to conserve moisture. Water plants deeply when top few inches of soil become dry.
– **Overwatering** – Excess moisture deprives roots of oxygen. Allow soil to dry out between waterings. Improve drainage if needed.
– **Root damage** – Compacted, damaged, or restricted roots are unable to take up water properly leading to curling foliage. Avoid wounding roots and improve soil conditions.
How to revive a dying hydrangea?
If your hydrangeas are wilting, browning, and struggling to thrive, try these troubleshooting tips:
– Improve soil drainage and aerate compacted soils so roots receive adequate oxygen.
– Move plants to dappled shade if they are getting scorched by too much direct sun.
– Water thoroughly allowing the soil to fully saturate. Continue deep watering during drought periods.
– Apply a balanced fertilizer to nourish plants if nutrients are lacking.
– Prune back any dead or diseased stems to improve air circulation.
– Remove spent blooms and old flowerheads to encourage new growth.
– Monitor for pests like aphids, scale, or spider mites and apply insecticidal soap if needed.
– Treat fungal diseases like powdery mildew with appropriate organic or chemical fungicides.
– Reset the pH closer to 5.5-6.5 if the current level is too high or low.
– Transplant into a bigger pot or plot if the roots are severely crowded.
– Protect plants from harsh winter weather and wind damage.
With a little TLC and proper growing conditions, stressed hydrangeas can make a comeback! But some very neglected plants may need replacing.
What are the best hydrangea varieties for containers?
Some top picks for growing hydrangeas in pots include:
– **Let’s Dance Series** – These reblooming bigleaf hydrangeas flower all summer into fall. Choose from many fun colors like Rhythmic Blue, Diva, and Starlight. Keep soil moist.
– **Cityline Hydrangeas** – Bred for urban tolerance, these panicle hydrangea series are compact, disease resistant, and prolific flowerers. Vienna and Paris are popular cultivars.
– **Endless Summer Series** – These famous remontant mophead hydrangeas bloom on both old and new wood for continuous flowers. Blushing Bride and Twist-n-Shout are award winners.
– **Incrediball** – A showy, large-flowered mophead that can grow up to 4 feet wide yet stays manageable. It produces big round blooms that change from lime green to bright magenta.
– **Little Lime** – One of the few dwarf hydrangeas, this compact shrub has pretty chartreuse-lime blooms. It makes an excellent potted specimen for small spaces. Stays under 3 feet tall and wide.
Conclusion
With proper siting, soil preparation, watering, and care hydrangeas can become outstanding garden performers. Pay attention to their specific growing requirements and you’ll be rewarded with these gorgeous shrubs’ abundant colorful blooms. Hydrangeas are such outstanding landscape plants that a little extra effort is well worth it. Just a few basic tips go a long way to help hydrangeas flourish and reach their full potential in your outdoor space.