Bigleaf (H. macrophylla) and Mountain (H. serrata) hydrangeas are the undisputed stars for anyone seeking spectacular flower colours, from electric blue to vibrant pink and rich red. Thanks to modern varieties, these summer jewels are more accessible than ever. This guide presents a selection of high-performing cultivars to help you choose the one that will illuminate your garden.
A Selection of Spectacular Cultivars
The secret to success lies in choosing modern reblooming cultivars. These exceptional plants not only flower on last year's wood but also on new stems from the current year, offering true flowering insurance.
In the following selection, you will discover varieties from two closely related but distinct families: Hydrangea macrophylla and Hydrangea serrata. Each offers its own unique styles and characteristics.
Bigleaf Hydrangeas (Hydrangea macrophylla)
Also known as hortensias, these are the "classic" hydrangeas that evoke lush summer gardens. They generally form well-filled, rounded shrubs with dense foliage of large, glossy, toothed green leaves. Their blooms come in two main forms: the famous "mopheads," which are impressive globes of flowers, and the "lacecaps," which are flat discs of small, fertile flowers surrounded by larger, more decorative florets.
Endless Summer® 'BloomStruck®' (H. macrophylla 'Bailmer')
One of the most popular cultivars in the series, 'BloomStruck®' is a true star. It stands out with its exceptionally sturdy red stems and dark foliage that provides a superb contrast. It produces mophead flowers of an intense violet in acidic soil or a vivid rosy-red in alkaline soil. In addition to being an excellent rebloomer, it is known for its very good disease resistance. (Hardiness: zone 4 | Height: 90 to 120 cm | Width: 90 to 120 cm)
Endless Summer® 'Summer Crush®' (H. macrophylla 'Bailmacfive')
Winner of several awards, including the "Retailers' Choice Award," this cultivar is a powerhouse of performance. It stands out for its intense colour and compact size, ideal for small gardens and containers. It produces large mophead flowers of a vibrant raspberry red or a neon purple, depending on soil acidity. (Hardiness: zone 4 | Height: 45 to 90 cm | Width: 45 to 90 cm)
Let's Dance Blue Jangles® (H. macrophylla 'SMHMES14')
This variety from the Let's Dance® series is a flower machine. It produces an abundance of mophead blooms, in a rich, true blue in acidic soil, or a light pink in more alkaline soil. It is a reliable reblooming variety with a compact, tidy habit that makes it easy to fit anywhere. (Hardiness: zone 4 | Height: 30 to 60 cm | Width: 60 to 90 cm)
Endless Summer® 'Pop Star®' (H. macrophylla 'Bailmacsix')
Known for being an extremely prolific rebloomer, 'Pop Star®' flowers very quickly and continuously. Its lacecap-style flowers are an electric blue or brilliant pink and are very attractive to pollinators. Its very compact habit makes it a star for small spaces and borders. (Hardiness: zone 4 | Height: 45 to 90 cm | Width: 45 to 90 cm)
'Starfield™' (Hydrangea macrophylla 'Hokomarevo')
This very floriferous cultivar produces unique double, star-shaped flowers in a vibrant bubblegum pink. Its ability to bloom and rebloom all summer ensures a constant presence of colour. In acidic soil, its colour will lean towards mauve-blue. It is a naturally compact shrub. (Hardiness: zone 5 | Height: 60 to 90 cm | Width: 60 to 90 cm)
Mountain Hydrangeas (Hydrangea serrata)
Close cousins of the macrophylla, mountain hydrangeas are distinguished by a more delicate and natural appearance. Their habit is generally smaller and more compact, with thinner stems. Their foliage consists of smaller, narrower leaves, often with a matte finish. The bloom is almost exclusively the "lacecap" type. One of their most interesting characteristics is their hardiness, which is often superior to that of the macrophylla.
Tuff Stuff Ah-Ha® (H. serrata 'SMNHSI')
Considered one of the most spectacular mountain hydrangeas, this reblooming variety produces enormous double flowers that resemble waterlilies. The flowers can be mauve-blue or pink, depending on the soil. Its name "Ah-Ha" comes from the reaction people have upon seeing it bloom. It is recognized for its abundant flowering and improved hardiness. (Hardiness: zone 4 | Height: 60 to 90 cm | Width: 60 to 90 cm)
'Pink Dynamo™' (H. serrata 'JPD-01')
This variety offers a striking colour contrast. Its lacecap flowers are a hot, electric pink that stands out beautifully against its dark, almost black foliage. In addition to its beauty, 'Pink Dynamo™' is known for its good heat tolerance, disease resistance, and appeal to pollinators. (Hardiness: zone 5 | Height: 60 to 90 cm | Width: 60 to 90 cm)
The Keys to Success: The User Manual
Now that you have discovered the beauty and diversity of modern cultivars, you might be wondering how to guarantee their performance in your own garden. It's simple! Success with these hydrangeas isn't about luck, but about knowing a few fundamental pillars.
Setup: Location and Planting
Success starts with the right location. Aim for a site that receives gentle morning sun and protective afternoon shade. Rich, fresh, and above all, well-drained soil is ideal. A spot sheltered from winter winds, where snow tends to accumulate, will also provide excellent natural insulation. Planting can be done in the spring after the last frost, or in the autumn.
Care and the Magic of Colour
Watering
Hydrangeas love moisture. Regular, deep watering is crucial, especially during the first year of planting and during summer heatwaves.
Mulching
Applying a 5 to 7 cm layer of organic mulch (wood chips, shredded leaves) at the base of the shrub is very beneficial. Mulch helps retain soil moisture, keeps roots cool, and limits weed growth.
Fertilizing and Colour
An application of compost at the base of the shrub in the spring is excellent practice. If you use a fertilizer, avoid those high in nitrogen (the first number in the N-P-K trio), which promote foliage at the expense of flowers. This is also where the magic happens: to get blue flowers, the soil must be acidic (pH < 6.5) and you can add aluminum sulfate. For pink or red flowers, the soil must be more alkaline (pH > 6.5), which an application of dolomitic lime will help achieve.
Pruning: The Right Cut at the Right Time
The rule is minimalism. Since these hydrangeas flower on "old wood," you should never prune live wood in the fall or early spring, otherwise you will cut off all the future flowers. The only necessary pruning is to remove dead wood in late spring, once the leaves have emerged.
Winter Protection: Preparing for Future Blooms
To protect the first and largest wave of flowers, proper winter insulation is the pros' trick. After the first frosts, install a wire mesh cage around the plant and fill it completely with a thick layer (30-60 cm) of shredded dead leaves.
With the right modern cultivar and these few techniques in your pocket, you are ready to successfully integrate these hydrangeas with their unparalleled colours into your landscape.
