Looking for the best blue hydrangea varieties? Here are some of the most reliable tried-and-true hydrangea cultivars with blue flowers to consider.
1. Endless Summer hydrangea
Endless Summer hydrangea is a popular variety known for its ability to bloom on both old and new wood. This is the original “reblooming hydrangea” and is now found in gardens all over the continent.
Hydrangea macrophylla ‘Endless Summer’ tends to grow to a mature size of 3-5 feet tall and 3-5 feet wide. It grows best in part shade, with direct sunlight in the morning but protected shade in the afternoon. ‘Endless Summer’ is hardy in Zones 4-9, although it may only bloom on new wood at the cooler end of this range.
Like many Hydrangea macrophylla cultivars, this hydrangea variety can change color. The flowers are typically blue when the plant is growing in acidic soil. In neutral or alkaline soil, however, the flowers tend toward pink.
For the deepest blue hydrangeas, bring soil pH down into the range of 4.5 to 5.5 or so. A pH level of 5.0 is a good target. You can apply soil acidifier products made from sulfur to bring the pH down to this level. You may also wish to add aluminum sulfate and avoid adding too much phosphorus to the soil for the richest blue tones. Depending on conditions, changing the hue can take a few months to a few years.
2. Nikko Blue hydrangea
Nikko Blue hydrangea is one of the most popular blue hydrangea varieties around. This variety has beautifully rounded heads of overlapping flowers, creating a stunning blue mophead.
Hydrangea macrophylla ‘Nikko Blue’ tends to grow to a mature size of 4-6 feet tall by 4-6 feet wide in a rounded shape. It grows best in partial shade and should be placed in a protected spot that does not get harsh direct sunlight in the afternoon but does not get too cold at night or in winter. ‘Nikko Blue’ is not particularly tolerant of overly hot or cold climates and grows best in Zones 6-9. It can sometimes be grown successfully in Zone 5 but will need significant winter protection for overwintering flower buds to survive.
As with ‘Endless Summer’ (see above), this variety does best in acidic soil. The pH should be in the range of about 4.5 to 5.5 for a deep blue tone. A soil acidifier can help to bring the pH of alkaline soil down to a good level for blue flowers. Adding aluminum sulfate can also help to limit the amount of phosphorus in the soil.
3. Penny Mac hydrangea
Penny Mac hydrangea is a classic cultivar that turns a lovely light blue in acidic soil. This splendid long-blooming variety has larger flowers than some blue hydrangeas and is one of the most heat-tolerant (and frost-tolerant) varieties available.
Hydrangea macrophylla ‘Penny Mac’ tends to grow to a mature size of 4-6 feet tall by 4-6 feet wide in a low-maintenance rounded shape. It grows best in partial shade or dappled sunlight but is more tolerant of midday sun than many other varieties on this list. ‘Penny Mac’ can be grown in Zones 5-9, although there may be some winter dieback of stems and dormant flower buds at the cooler end of this range.
‘Penny Mac’ was named after Penny McHenry, the founder of the American Hydrangea Society. This famous rebloomer was used alongside Endless Summer in the breeding of many other popular reblooming hydrangea varieties.
4. Nantucket Blue hydrangea
Nantucket Blue hydrangea is a selection from ‘Nikko Blue.’ It is very similar to ‘Endless Summer’ and is another rebloomer that can flower on both old wood and new wood.
Hydrangea macrophylla ‘Nantucket Blue’ tends to grow to a mature size of 4-6 feet tall and wide in a mounding shape. It grows best in partial shade with protection from intense afternoon sun and cold temperatures. This blue hydrangea variety is hardy in Zones 5-9, although it may only produce flowers on new wood in Zones 5-6.
5. Blue Enchantress hydrangea
Blue Enchantress hydrangea is a reblooming hydrangea similar to ‘Endless Summer.’ This one tends to be somewhat more reliable in Zones 4-5, where harsh winters kill the plant’s aboveground portion and lead to decreased blooming during the following summer. It also has dark red stems, which are quite ornamental. Blue Enchantress hydrangea is sold by Monrovia.
Hydrangea macrophylla ‘Blue Enchantress’ typically reaches a mature size of 3-5 feet tall and 3-5 feet wide. Like Endless Summer, it blooms best with a bit of morning sun but prefers a protected shady location in the afternoon. ‘Blue Enchantress’ can be grown in Zones 4-9, although it may only bloom on new wood in Zones 4-5 when winters are harsh.
6. Big Daddy hydrangea
Big Daddy hydrangea is a large blue hydrangea cultivar. Its blue flowers are quite large and can reach 12 inches across. This cultivar is offered for sale by Southern Living Plants.
Hydrangea macrophylla ‘Big Daddy’ usually reaches 5-6 feet tall and wide. It grows best in partial shade, but a bit of direct sunlight in the morning can help it bloom well. ‘Big Daddy’ was developed in the southern states and can be grown in Zones 6-9.
7. Mini Penny hydrangea
Mini Penny hydrangea is a small blue hydrangea variety that is great for containers or smaller gardens. This rebloomer has the same blue flowers as Penny Mac, but it is much more compact and can reach just 2-3 feet tall and wide.
Hydrangea macrophylla ‘Mini Penny’ does best in partial shade with morning sun, making it a great choice for containers or small areas. It is hardy in Zones 5-9 and can handle intense heat better than some blue hydrangea varieties. ‘Mini Penny’ can also tolerate cold temperatures down to -25°F, so it is an excellent choice for colder climates. The blue flowers will turn pink in alkaline soil and stay blue in acidic soil. It tends to rebloom from summer into fall, providing lots of color throughout the growing season.
8. Felicity hydrangea
Felicity hydrangea is a blue-violet variety with unique blue-purple flowers that fade to pink as they age. This variety is sold by Monrovia and Proven Winners.
Hydrangea macrophylla ‘Felicity’ grows 3-4 feet tall and wide in a mounded shape. This blue hydrangea prefers partial shade, but can tolerate some direct sun in the morning. It’s hardy in Zones 5-9, although it may not flower in Zones 5-6 during cold winters. The blue flowers will turn pink in alkaline soil and stay blue in acidic soil.
9. Blue Jangles hydrangea
Blue Jangles hydrangea is a blue rebloomer bred to be more winter hardy than the popular ‘Endless Summer’ blue hydrangea. It produces blue flowers from spring into fall and is sold by Monrovia.
Hydrangea macrophylla ‘Blue Jangles’ grows to a mature size of 4-5 feet tall and wide in a mounded shape. This blue hydrangea prefers partial shade, but will tolerate some direct sun in the morning. It is hardy in Zones 4-9, and can tolerate temperatures down to -30°F (albeit with some winter dieback). The blue flowers will turn pink in alkaline soil and stay blue in acidic soil.
10. Cape Cod hydrangea
Cape Cod hydrangea is a blue variety that is bred for improved winter hardiness and better flowering. This blue hydrangea is sold by Monrovia, Proven Winners and other nurseries.
Hydrangea macrophylla ‘Cape Cod’ grows 3-5 feet tall and wide in a mounded shape. This blue hydrangea prefers partial shade, but can tolerate some direct sun in the morning. It’s hardy in Zones 4-9, and can tolerate temperatures down to -25°F. The blue flowers will turn pink in alkaline soil and stay blue in acidic soil. ‘Cape Cod’ tends to rebloom from summer into fall, providing lots of color throughout the growing season.
11. Zorro hydrangea
Zorro hydrangea is a popular compact lacecap variety. The flat, pretty flower clusters are held up on dark stems. Like the mopheads above, this variety requires acidic soil and proper nutrition for deep blue flowers.
Hydrangea macrophylla ‘Zorro’ grows to about 3 feet tall and 2-3 feet wide. This small plant adapts very well to being grown in a container. It prefers partial shade, but can tolerate some direct sun in the morning. The blue flowers will turn pink in alkaline soil and stay blue in acidic soil. ‘Zorro’ is hardy in Zones 5-9, providing lots of blue color throughout the growing season.
12. Rhythmic Blue hydrangea
Rhythmic Blue hydrangea is a blue mophead hydrangea variety bred for good performance in cold climates. This plant can be grown in Zones 5-9, but really shines in Zones 5-6 where some of the other varieties on this list can struggle with the harsh winters.
Hydrangea macrophylla ‘Rhythmic Blue’ grows 3-4 feet tall and wide in a rounded shape. This blue hydrangea prefers partial shade, but can tolerate some direct sun in the morning. The blue flowers will turn pink in alkaline soil and stay blue in acidic soil. ‘Rhythmic Blue’ tends to rebloom from summer into fall, providing lots of blue color throughout the growing season.
13. Starlight hydrangea
Starlight hydrangea is a blue lacecap reblooming cultivar from Proven Winners’ Let’s Dance line of everblooming hydrangeas. It features blue to blue-violet flowers and can be grown in Zones 5-9.
Hydrangea macrophylla ‘Starlight’ is a smaller cultivar, growing 2-3 feet tall and wide in a mounded shape. This blue hydrangea prefers partial shade, but will tolerate some direct sun in the morning. The blue flowers will turn pink in alkaline soil and stay blue in acidic soil. ‘Starlight’ is known for reblooming from spring into fall, providing lots of blue flowers all season long.
14. Blue Cassel hydrangea
Blue Cassel hydrangea is another lace cap variety with particularly vibrant blue flowers in acidic soil. Like Starlight, it can be grown in Zones 5-9.
Hydrangea macrophylla ‘Blue Cassel’ is a medium-sized variety, generally growing to a rounded shape about 4 feet tall and wide. This blue hydrangea prefers partial shade, but will tolerate some direct sun in the morning. The blue flowers will turn pink in alkaline soil and stay blue in acidic soil.
15. Rio hydrangea
Rio hydrangea was a blue-purple cultivar previously offered by Proven Winners as part of their CityLine series of hydrangeas. Unlike the newer varieties on this list, ‘Rio’ blooms only on old wood. If you can’t find an old ‘Rio’, consider compact ‘Blue Jangles’ or the new ‘Sky View’ cultivars.
Hydrangea macrophylla ‘Rio’ is a compact variety, growing about 2-3 feet tall and wide. This blue hydrangea prefers partial shade but will tolerate some direct sun in the morning.
16. Spike hydrangea
Spike hydrangea is a unique ruffled variety with blue flowers in acidic soil or pink flowers in alkaline soil. Like ‘Rio,’ this variety blooms on old wood and so should be pruned carefully (ideally in the summertime right after the blooms fade).
Hydrangea macrophylla ‘Spike’ grows around 3-4 feet tall and wide, growing in a rounded shape. This variety is less common than some of the others on this list, but may be available from specialty nurseries.
17. Twist-n-Shout hydrangea
Twist-n-Shout hydrangea is a blue lace-cap variety from the Endless Summer series of hydrangeas. It is hardy in Zones 4-9 and will bloom from early summer into fall.
Hydrangea macrophylla ‘Twist-n-Shout’ grows 3-5 feet tall and 3-4 wide in an upright mounded shape. This dependable shrub may not bloom until mid-summer in the coldest growing zones.
18. Pop Star hydrangea
Pop Star hydrangea is a new cultivar from the Endless Summer line from Bailey Nurseries. This adorable new offering is quite small, growing to a rounded ball about 1.5 to 3 feet tall and wide. Try this new lacecap in a low hedge along a pathway for all-season blooms.
19. Peacock hydrangea
Peacock hydrangea is a rebloomer with blue-purple flowers and black stems. This unique variety has an upright oval shape, growing to 3-5 feet tall and 2-5 feet wide. It can be grown in USDA Zones 5-9.
20. Together hydrangea
Together hydrangea is a unique blue mophead variety where each flower has double petals. This variety is part of the Forever and Ever line of reblooming hydrangeas. It grows in a low mounded form, about 2-3 feet tall and 3-4 feet wide.
21. Venice hydrangea
Venice hydrangea is a blue bigleaf hydrangea from the Proven Winners CityLine series. It’s an older variety that blooms only on old wood, so avoid any significant pruning in winter or spring. This cultivar is hardy in Zones 5-9.
22. Hamburg hydrangea
Hamburg hydrangea is a blue-purple decorative mophead variety. It grows to about 4-5 feet tall and wide. ‘Hamburg’ is also part of the Cityline series.
23. Game Changer Blue hydrangea
Game Changer Blue hydrangea is an everblooming blue lacecap variety in the “Gamechanger” series by Growing Colors. This small plant grows to about 2 feet tall and wide at most.
24. Azure Skies hydrangea
Azure Skies hydrangea is a blue mophead variety. This hydrangea can grow to about 3-5 feet tall and wide, in a round mounded shape.
25. Otaksa hydrangea
Otaksa hydrangea is a small pink or blue lacecap variety (depending on soil pH). This cultivar is quite elegant and grows to a compact mature size of 2-3 feet tall and 2-4 feet wide.
26. L.A. Dreamin’ hydrangea
L.A. Dreamin’ hydrangea is a reblooming hydrangea that tends to grow different colored blooms on the same plant. Depending upon soil conditions, you may observe pink-purple and blue flowers on the same shrub. This plant grows to a mature size of 4-5 feet tall and wide.
