How to Achieve the Right Colour for Your Hydrangeas

Hydrangeas have flowers in various color shades. However, to bloom abundantly, they need the right location and care. If your hydrangea is not blooming, or its flowers are faded and green instead of colorful, the following article will help you...

Hydrangeas arrived in our regions at the beginning of the 19th century from Japan. These abundantly flowering shrubs quickly found their place in various types of ornamental gardens. Now you can grow both classic, bushy varieties, as well as tree-form or climbing hydrangeas. You can choose from cultivars with blue, purple, white, cream, pink and red flowers. Depending on the variety, they bloom between March and July.

You will read here: types of hydrangeas, location, care and pruning, flower color changes, overwintering, diseases and pests, container growing

Types of Hydrangeas

In our conditions, the most commonly grown is the bushy bigleaf hydrangea (Hydrangea macrophylla). It exists in a large number of differently colored cultivars.

Pergolas, fences or walls can be covered by climbing hydrangea (Hydrangea petiolaris). White inflorescences don't form classic spheres and are smaller. It doesn't require much sun, care or regular pruning.

Smooth hydrangea (Hydrangea arborescens) is a robust shrub with large, mostly white spherical inflorescences. It's more vigorous than bigleaf hydrangea. It requires sufficient care.

With its atypical conical flowers, panicle hydrangea (Hydrangea paniculata) stands out among hydrangeas. For abundant flowering, it requires annual deep pruning, otherwise it grows very vigorously (up to 2 m) at the expense of flowering.

Hydrangeas Are Selective

These shrubs have somewhat special requirements for their location, but these aren't too difficult to meet. The amount of light, soil and moisture are particularly crucial. For hydrangeas, partial shade is ideal, though they can tolerate even greater shading. In direct sun, they usually don't thrive. North or west exposure is usually best.

The soil should be at least slightly acidic and contain as little limestone as possible. We can increase acidity by mixing peat into the soil where the plant will be planted. As for water quantity, the soil should be slightly moist, but not permanently waterlogged. During the period of intensive growth and flowering, hydrangeas will need quite a lot of moisture.

Care Throughout the Year and Pruning

Hydrangeas form inflorescences in the previous year on the tips of current year's shoots. Therefore, we prune only in early spring. We don't shorten the branches, we only remove weak shoots.

Pink-flowering shrubs that we want to encourage to bloom blue respond best.

Hydrangeas need occasional fertilizing or watering. In both cases, rainwater is ideal. Tap water often contains large amounts of calcium, which hydrangeas cannot tolerate. Therefore, avoid watering with tap water, especially if you have hard water in your area.

We fertilize during the growing season once every two weeks, preferably with a fertilizer designed specifically for hydrangeas.
Pruning of hydrangeas is done in early spring. This especially applies to the classic bigleaf hydrangea, though the procedure may differ for other species.

Hydrangeas set flower buds during summer, which then overwinter and only bloom the following year. They can often be damaged by frost. Flower buds are always found at the tip of the current year's growth - these are the largest buds. So if we were to cut back the current year's shoots by a third, as many guides advise, we would lose all the flower buds and the hydrangea wouldn't bloom at all.

When pruning, we select (depending on the size and age of the plant) about 5-15 strong, non-flowered shoots with an undamaged terminal bud. These shoots should be evenly distributed and shouldn't cross each other. We remove all remaining thin, spent, and crossing shoots. This prevents overcrowding and excessive leaf growth at the expense of flowering.

Change the Color of Your Hydrangea Flowers

Not satisfied with the color of your plants' flowers? Or did you buy a beautifully colored hydrangea, but the flowers gradually lost their vibrancy and turned green? Then it's probably due to pH or a deficiency of some element, especially aluminum.

These two factors are closely related, because aluminum is only available to plants in acidic conditions. This element is essential for blue flower coloration. In acidic soil, the flowers are most commonly blue, while in more neutral conditions they become increasingly pink.

How to Protect Hydrangeas from Frost

Hydrangeas need to be prepared for winter. Already in August, we stop fertilizing and reduce watering so that the wood and buds have enough time to mature properly. Dry flowers can remain on the plant throughout winter - there's no need to cut them off.

At the end of autumn, we mound up a layer of soil, mulch, conifer branches, or leaves around the base to protect the crowns from frost. Young, small plants, which are more susceptible to freezing, can be protected entirely, for example with a burlap sack or horticultural fleece.

When Hydrangeas Fall Ill

Hydrangeas can also be affected by diseases or pests. This happens especially in unsuitable locations or with insufficient nutrition.

Chlorosis (yellowing) of leaves is often caused by iron deficiency in the soil. The leaf veins remain green. The disorder can be corrected by supplying iron, either separately or as part of a fertilizer with micronutrients.

Grayish coatings on leaves can be caused by powdery mildew or gray mold. This occurs especially during wet weather. If the damage is more extensive, we can use a fungicide spray.

Yellowish or rusty rings on leaves, flowers, and green shoots are caused by a virus. They can be relatively easily distinguished from other diseases. If your hydrangea is affected by this disease, unfortunately it's best to remove the entire plant - it would gradually deteriorate and the virus could spread to other plants, including edible ones.

Among animal pests, we may find aphids, spider mites, and nematodes on hydrangeas. In the case of aphids or spider mites, the infestation is usually not severe, but if necessary, we can use insecticides. Nematodes live in the soil and manifest on the plant as deformities of leaves and stems, flowering is limited and flowers become stunted. Getting rid of nematodes can be difficult, but preparations exist even against them.

The color and shade of flowers can therefore be influenced to some extent by aluminum and soil acidity. Bigleaf hydrangea reacts quite strongly to these factors. However, limitations set by the variety apply here as well. White-flowering cultivars probably won't change color no matter what you do.

Blue varieties may turn pinkish in neutral soil, but they will likely grow and bloom poorly, and the coloring won't be very attractive either.

In such cases, it's necessary to increase acidity and supply the required aluminum. We can lower pH by adding peat to the soil, or (if the plant is already planted) by mulching it around the base of the plant.

We don't fertilize with fertilizers that bind iron; instead, we choose an acidic fertilizer with high aluminum content. Plants usually don't require this element, so common fertilizers don't contain it. However, there are fertilizers specifically for blue-flowering hydrangeas on the market, which are most suitable. We start fertilizing at least 1 month before flowering so the results are visible.

Hydrangeas Indoors

Hydrangeas can also be grown in containers. The requirements are basically the same, you just need to have a sufficiently large container and water frequently. Hydrangeas also require frequent repotting, young plants sometimes need to be repotted even twice a year.

Hydrangeas are suitable for cutting and drying. Hydrangea arrangements look stunning - whether used alone or in combination with other flowers.

In winter they require overwintering in a cool, bright, frost-free room. In spring we can move them outside for the summer or keep them in a bright spot indoors - if the plant is not in direct scorching sun, it will bloom longer indoors in summer, where it's cooler than outside.

Proven products needed for growing hydrangeas can be found in our range!

Written by Eliška Kadlecová