Inverted hydrangeas are hydrangeas whose flower heads look like flat caps with a ruffled edge, which gave the shrubs their unusual but apt name. Like mophead hydrangeas, inverted hydrangeas belong to the species of bigleaf hydrangea (Hydrangea macrophylla), which is native to Japan.
While all inverted hydrangea flower heads have a central set of small flowers surrounded by more showy flowers, shrubs vary in size, flower color and bloom time. Broad, dark green, toothed leaves provide a lush background for the large, flattened flower heads. Like most hydrangeas, these are fast-growing shrubs, growing an average of two feet or more per year. Planting time is in fall or early spring.
Inverted Hydrangea Care
Here are the key care requirements for growing an inverted hydrangea:
When planting hydrangeas, carefully consider the location. Find the right balance between enough sunlight, which is essential for lush blooms, and not too much, especially in the hot afternoon sun, which the plant will suffer under.
Make sure the plant is getting enough moisture.
Space a group of plants according to the variety, as the mature sizes of mophead hydrangeas vary.
Add aluminum sulfate to the soil to turn the flowers blue, or add lime to the soil to turn the flowers pink.
Light
Mophead hydrangeas grow best when planted in a location that gets partial sun. A location with morning sun and afternoon shade is ideal. The foliage may become limp, yellow, or burn in full sun. However, if the hydrangea is planted in too much shade, the stems may become weak and produce fewer flowers.
Water
It is absolutely necessary that mophead hydrangeas receive enough water, but they cannot tolerate overwatering. If you are unsure if the plant needs water, stick your finger about four inches deep into the soil. If it feels dry, the hydrangea needs water.
If it doesn’t rain heavily once a week, water deeply until the soil is saturated without letting it become waterlogged. Frequent watering with a light mist is not beneficial to the plant, as the water needs to reach the roots. It is best to water deeply to soil level and not so often.
Soil
Mounted mound hydrangeas require rich, well-drained, evenly moist soil that has been amended with organic matter such as fertilizer or compost. In some varieties (except those with white flowers), flower color changes with soil acidity. Acidic soil (a pH of 5.5 or less) will result in blue flowers, while alkaline soil (a pH of 7.0 or more) will cause the flowers to turn pink.
To help the soil retain the moisture these shrubs need, consider piling up several inches of organic mulch around the shrub. Avoid piling up the mulch around the stems.
Temperature and Humidity
The winter hardiness of the lacecap hydrangea depends on the variety, but in general it thrives better in moderately warm weather and humidity than in a hot, humid summer climate.
Also check the variety’s hardiness zone to make sure the plant you choose can withstand winter temperatures in your area. Some varieties won’t survive the cold below zone 6.
Fertilizer
Fertilizer will definitely encourage growth. Applying a balanced fertilizer in early spring according to product label directions is recommended. You can also mix organic compost into the soil each year.
Fertilizing should be limited to spring and never done in late summer, as fertilizing encourages new growth. Late growth is especially susceptible to winter damage.
Types of mophead hydrangeas
Here are some popular mophead hydrangea varieties:
‘Twist-n-Shout’: a reblooming pink or blue mophead hydrangea that is part of the Endless Summer hydrangea series
‘Bluebird’: sea-blue flowers surround a large cluster of bright blue flowers and reddish fall foliage
‘Zorro’: deep blue flowers on strong and upright purplish-black stems and reddish fall foliage
‘Lanarth White’: white flowers in a border ring around a cluster of light pink or blue flowers
‘Lady in Red’: a compact (two feet tall and three feet wide) variety with red stems and red-veined leaves
Pruning
When pruning hydrangeas, it is important to know whether the variety blooms on this year’s growth (new wood) or last year’s growth (old wood). Like all large-leaf hydrangeas, mophead hydrangea blooms on old growth. Prune the plant immediately after flowering in summer.
Dead or diseased stems can be removed at any time of year. Removing spent flowers is optional. Many gardeners leave the spent flowers intact over the winter.
Propagation
Propagation of lacecap hydrangeas is possible, but is limited by two factors. Most varieties are cultivated cultivars, so propagation from seed will not produce a true plant and is therefore not recommended. The other limitation is that propagation of protected cultivars is prohibited.
For non-protected varieties, you can grow a new shrub from softwood stem cuttings of the current season’s growth. A good time to do this is early summer, as the cutting will then have plenty of time to take root and you can plant it in the fall. Here’s how to do it:
Using clean, sharp pruning shears or a knife, cut off a strong, healthy stem tip with no flowers and that has at least one growth node (a knotty line above the stem).
Remove the leaves from the bottom half of the cutting.
Dip the end of the cutting in rooting hormone.
Fill a 4-inch pot with moist, sterile potting soil. Poke a hole in the soil with a pencil or stick and insert the cutting deep enough so that the growth node is buried in the soil. Firmly tamp the soil around the stem.
Place the pot in a bright, warm spot, but out of direct sunlight. Make sure the soil stays evenly moist, but not soggy.
Within a few weeks, you should see new growth on the cutting and you can transplant the plant into garden soil or a larger container. Be sure to harden off the plant before transplanting it into the garden.
Potting and Repotting
The lacecap hydrangea can be grown in a container. Plant it in a pot with large drainage holes that are a little wider and deeper than the one you bought it in, so it can grow a little before repotting. A terracotta container is ideal because it allows excess moisture to evaporate and the material is heavy, so the plant won’t fall over easily. Fill the container with well-draining potting soil.
Hydrangeas in pots need frequent watering to keep them from drying out. Lack of water is the main reason a potted hydrangea will die.
When the roots outgrow the drainage holes or the plant becomes root-bound, it’s time to repot the hydrangea into a larger container. Choose a pot one size larger and fill it with fresh potting soil before moving the shrub to its new home.
Overwintering
When grown within their hardiness range and in garden soil, mophead hydrangeas don’t need winter protection. However, the roots of potted plants should be insulated with a thick layer of mulch and the container should be wrapped in burlap and a layer of bubble wrap or placed in an insulating silo to protect the roots from winter frost.
Common Pests and Plant Diseases
Mounted mophead hydrangeas are susceptible to fungal diseases such as bacterial wilt, leaf blight, leaf spot and powdery mildew. Spacing plants properly and avoiding overhead watering can minimize the risk of fungal spread. Inverted hydrangeas attract aphids. Severe infestations may require the application of neem oil or insecticidal soap.
How to Make Inverted Hydrangeas Bloom
Blooming Months
Inverted hydrangeas generally bloom from mid to late summer, but the exact schedule varies by variety. Some even bloom into fall.
How Long Do Inverted Hydrangeas Keep Their Blooms?
The beauty of hydrangeas is that the blooms remain attractive even after they are freshly aged and can even dry on the bush.
What Do Inverted Hydrangea Flowers Look and Smell Like?
Inverted hydrangea flower heads are white, pink, or blue, and consist of a flat ring of (usually) four-petaled flowers surrounding a spike-shaped cluster of smaller flowers. You can affect the color of the blue or pink blooms by changing the acidity or alkalinity of the soil. Hydrangeas are not fragrant.
How to Encourage More Blooms
Common reasons hydrangeas don’t bloom include too much shade, pruning at the wrong time of year (which removed flower buds), or a late spring frost after a warm spell that killed the flower buds.
If the shrub is large and can’t be transplanted, prune surrounding trees or shrubs to let in more sunlight. As for pruning, once you adjust your pruning schedule, it will recover and bloom next year.
Removing the spent blooms from mophead hydrangeas
Hydrangeas make beautiful cut flowers and it won’t hurt the shrub, so don’t be afraid to snip a few for vases indoors.
Removing the spent blooms from mophead hydrangeas will make room for the next bloom. Remove the spent blooms just below the flower head and above the next pair of leaves.
Common Problems with Lacecap Hydrangeas
Hydrangeas are not demanding plants, but they do need the right location, sun exposure and soil. Watch for these potential problems.
Yellow Leaves
Yellow leaves can indicate too much water, too little water or too much fertilizer. First, check the water level. If the soil is waterlogged, let it dry out. If it is clearly thirsty, give it plenty of water at soil level. If you suspect over-fertilization, use a drip hose to flood the plant’s root zone, but don’t let water stand. Repeat every few days to allow the fertilizer to penetrate deeper into the soil, away from the roots.
Drooping Leaves
If the leaves drop midday, resist the temptation to turn on the hose. The hydrangea probably doesn’t need water; the plant is protecting itself from hot temperatures and will bounce back when temperatures cool in the evening.
Browning Leaves
Brown spots on leaves can be caused by a fungal or bacterial disease. If the leaf tips or edges are brown, it can also be caused by too much fertilizer or aluminum sulfate added to the soil. Rinse again with water to remove any overdose of fertilizer or aluminum sulfate salts.