Comprehensive hydrangea care: changing bloom color with soil pH, correct pruning timing, popular variety profiles, and container vs. garden planting tips.
Hydrangeas are representative Japanese flowering plants that add color to the rainy season. With their pompom-shaped flowers that bloom in abundance, they have a unique charm among plants in their rich color variations, and their flower color can be changed depending on the soil properties. Here we explain the basics of hydrangea cultivation, from managing flower color to pruning and variety selection.
How Hydrangea Flower Color is Determined
Hydrangea flower color changes are related to the amount of aluminum ions absorbed from the soil.
- In acidic soil, aluminum dissolves easily and is absorbed through the roots, resulting in blue flowers
- In alkaline soil, aluminum does not dissolve easily and is not absorbed, resulting in pink flowers
- Near neutral pH, colors become a purplish intermediate shade
- White flower varieties (such as Annabelle) do not contain anthocyanins, so they remain white regardless of soil pH
- To make flowers blue, mix unadjusted peat moss or aluminum sulfate into the soil
- To make them pink, mix dolomitic limestone to shift toward alkaline conditions
Even on the same plant, the color may vary subtly from flower cluster to flower cluster, creating the beautiful gradient that is characteristic of hydrangeas.
Pruning Timing and Methods
The golden rule for hydrangea pruning is to do it immediately after flowering. Timing it wrong will prevent flowers from blooming the following year.
- Prune by mid-July once the flowers have finished. The basic technique is to cut 2-3 nodes below the flower
- Hydrangeas form next year's flower buds from August to September. If you prune after this period, you will cut off the flower buds
- Do not prune in fall and onward. If you must reshape the tree, cut only branches that do not have flower buds
- Thin out old branches from the base of the plant to improve air circulation. Branches older than 3 years will produce fewer flowers
- If the entire plant has become too large, do heavy pruning right after flowering. The following year will have no flowers, but it will recover from the year after
- Annabelle (American Hydrangea) blooms on new wood, so flowers will bloom in spring even if cut back to ground level in winter
Since the way flower buds form differs by variety, it's reassuring to check the pruning method at the time of purchase.
Popular Hydrangea Varieties
In recent years, plant breeding has advanced, allowing us to enjoy a diverse range of hydrangeas.
- Temari Temari: Double-flowered pompom type. With delicate petals overlapping, it has a luxurious appearance
- Kaleidoscope: A beautiful variety with white picotee edging on the flower petals. Also popular as a potted plant gift
- Annabelle: Large white pompom-shaped flowers. Blooms on new wood so pruning is simple. Also suitable for dried flowers
- Sumida no Hanabi: A representative variety of lacecap hydrangea. Star-shaped ornamental flowers bloom like fireworks
- Dance Party: A gorgeous variety with slender petals that seem to dance as they bloom
- Oak-Leaf Hydrangea: Has large leaves resembling oak leaves and produces cone-shaped white flowers. The autumn foliage is also beautiful
When selecting varieties, consider not only the flower form but also the sunlight conditions and space of the planting location.
Potted Plant and In-Ground Planting Management Tips
Hydrangeas can be enjoyed both as potted plants and in-ground plantings, but the management tips differ for each.
- Potted plants: Water easily dries out, so watering twice a day (morning and evening) is necessary in summer. Repot once every 1-2 years
- In-ground planting: Will grow in half-shade to shade, but a location where it receives sunlight in the morning is ideal
- Avoid locations with strong afternoon sun as they are prone to leaf scorch and flower color fading
- Fertilize in March and July after flowering with slow-release fertilizer. In winter, apply compost as winter fertilizer around the base of the plant
- Easy to propagate by cuttings. In June, cut about 2 nodes of new shoots and insert into cutting soil
- In winter, the plant loses its leaves and appears dead, but it will sprout new growth in spring, so do not worry
Since hydrangeas are plants that like water, the basis of management is to "never let them dry out."
Finding Hydrangeas on Br-choku
On Br-choku, you can purchase a diverse range of hydrangeas, including rare varieties, directly from specialized producers. A major advantage is that you can consult with producers about how to bring out flower colors and selecting varieties suited to your region's climate. Try finding hydrangeas on Br-choku to make your rainy season garden vibrant with color.