Bigleaf Hydrangea (Hydrangea macrophylla) are the most popular Hydrangeas, because of their large clusters of flowers and large dark-green foliage. These Japanese natives have early to late summer flowers of pink, blue, or white with shades in between that create a very colorful display. Bigleaf Hydrangeas prefer part-shade with moist well-drained soil. The soil should be rich in organic material to lessen moisture variability. In the summer additional water is required when Bigleaf Hydrangeas show signs of wilting. The large foliage does not hold up well in full sun. Good air movement is also important, because if the foliage stays wet powdery mildew can be a problem.
Planting is best done when they are not in bloom. If they are purchased with flowers, it is best to cut them off to lessen the transplant shock. Dig a hole that is two to three times as wide as the container and slightly deeper. Composted pine bark or peatmoss should be mixed into the existing soil. Half soil and half organic material is a good ratio. Bigleaf Hydrangeas should be mounded slightly to help with drainage, but don’t cover any part of the plant that is above the soil line. Mulch with pinestraw or composted hardwood mulch, but be careful not to put it up against the plant.
Large showy clusters of blue or pink flowers.A slow-release fertilizer in the early spring will get them off to a good start. No late season fertilizing is recommended on Bigleaf Hydrangeas, because they need to go dormant to prevent winter injury. Most flowering is done on late season growth. Care should be taken to not prune after August 1st. Mid-spring frost and freezes can harm the buds and new foliage. If new growth or swelling buds can be seen, then a sheet should be used to cover them on nights below 35 degrees. Pruning is best done after flowering. Dead wood can be removed anytime.
Flower color can be tricky on the blue varieties. If the ph. of the soil is low (acidic), then aluminum is available to the plant and the result is blue flowers. If the ph. is high, then the aluminum in the soil is unavailable for the plant and the flowers will be pink. Aluminum sulfate can be added to make the flowers bluer, but if the ph. is low they will still be on the pink side. Sulfur will help lower the ph., but it takes a year or longer to see the results. If pink is the color of choice, then dolomitic lime will raise the soil ph. The foliage is better in slightly acidic soil.
There are two distinct flower types of Bigleaf Hydrangea. The mophead (hortensia) form have large round balls of flowers. The lace-cap form have flat clusters of flowers. Mopheads are the most popular, because of their large showy flowers. The lace-caps have their place in the garden, because they tend to be smaller and the flowers are more delicate.
Popular Varieties of Bigleaf Hydrangea (Hydrangea macrophylla):
- ‘Nikko Blue’ – Mophead – Very popular variety that is a vigorous grower to 6 feet high and wide. Widely available in garden centers. Blue or Pink
- ‘Endless Summer’ – Mophead – Patented variety that has become very popular. Blooms on old and new wood which makes it an extremely reliable bloomer in areas that usually get late season freezes. Blue or Pink.
- ‘Fasan’ – Lace-cap – Blue or pink vigorous growing variety with sturdy stems. Great for cut flowers.
- ‘Harlequin’ – Mophead – Pink flowering variety in which every flower is edged in white. Very cool!
- ‘Blue Bird’ – Lace-cap – Delicate blue flowers on a smaller growing variety. Very reliable.
- ‘Tokyo Delight’ – Lace-cap – Pale blue flowers that fade to white on a compact plant.
- ‘Pia’ – Mophead – Lavender or Red flowers on a variety that can be kept less than 2 feet tall.
- ‘Blue Wave’ – Lace-cap – Vigorous popular variety that is very reliable. Blue flowers.
- ‘All Summer Beauty’ – Mophead – Another blue or pink variety that blooms on new and old growth.
- ‘Glowing Embers’ – Mophead – Long flowering red variety that foliage tinged in red.
‘Mariesii’ – Lace-cap – Vigorous growing blue variety.
‘Mariesii variegata’ – Lace-cap – Blue flowers with leaves edged in white.
‘Teller White’ – Lace-cap – Sturdy white flowering variety. Very reliable.
Attributes of Bigleaf Hydrangea
- Low Maintenance
- Large Showy Flowers
- Hardiness – Zones 5-9
- Height – 2-6 feet depending on variety
- Scientific Name: Hydrangea macrophylla