Beautiful and huge flower heads are the main reasons that gardeners around the world adore their hydrangea plants. Being relatively easy to grow and care for just makes them even more lovable.
You can encourage your hydrangeas to produce a greater abundance of flowers, and even bigger blooms so that you can enjoy their magnificent floral display even more by fertilizing hydrangeas.
But there are some basic rules to follow to make sure you get the results you want and not just a lot of luscious leaf growth.
The first thing to look at is the soil in which the hydrangea is growing. If it is already rich and contains plenty of organic matter, it may be that you don’t need to fertilize at all. Hydrangeas are acid-loving plants, and a soil test will provide you with the pH level of your soil, as well as its existing levels of nutrients and minerals.
Fertilizing a hydrangea too much is more damaging than not feeding it at all. Although an undernourished hydrangea bush will not perform as well as it should, it is unlikely to die.
However, applying too much fertilizer can lead to a condition known as fertilizer burn. The leaves and flowers will become crisp and dry due to scorching, and the leaves will burn. The roots will also burn, and the plant will, in most cases, wilt and die.
A soil test will confirm the level of nutrients in the ground, and you will be able to prevent this from happening.
Which Species of Hydrangea Are You Growing?
It’s important to know the species of hydrangea plant, as the different types of shrubs have different fertilizer requirements. The timing of fertilizer applications is also different, depending on the variety of hydrangea you wish to feed.
In general, a spring fertilizer application will give your hydrangea shrub a good boost for the growing season, with a follow-up application given in early summer to keep the flowers blooming for longer.
Most importantly, never give fertilizer to hydrangeas at the end of the summer or later in the year; additional nutrients at this time will encourage the formation of new, tender growth. This new growth and the emergent flower buds may be damaged by periods of winter cold.
Mopheads and Lacecaps
Bigleaf hydrangeas are the widest grown type of hydrangeas and include the most popular mophead and lacecap varieties. These shrubs need feeding regularly in the spring and early summer, unless you are using a slow-release fertilizer product that requires only one or at the most two applications a year.
Oakleaf and Panicle Hydrangeas
These hydrangeas require slightly less fertilizer than the bigleafs, but again the applications should be made in late spring and early summer.
H. arborescens, or smooth hydrangea, is somewhat different from the other species of hydrangea. This variety only needs an annual feed, which should be carried out in late winter, but before the soil warms up in the spring.
What’s The Best Fertilizer for Hydrangeas?
All fertilizers are different, and you should make sure you read the instructions on the packaging carefully to avoid overuse or incorrect use of the chemicals the products contain.
Because fertilizer can put a lot of pressure on a plant to produce vigorous new growth and flowers, the best type to use is a product that releases its nutrients slowly. Slow-release fertilizers are usually more expensive to buy, but in many cases, they are only applied once or twice a year. The hydrangea will receive a balanced dose of nutrients regularly.
Compositions that are intended for shrubs and trees are suitable for hydrangea plants too. It is also possible to get fertilizers that are specially produced for hydrangea shrubs. These will be fertilizers designed for acid-loving plants, including rhododendrons, azaleas, camellias.
A balanced fertilizer, such as a 10-10-10 which contains equal quantities of nitrogen (N), phosphorus (P), and potassium (K), is suitable for hydrangeas. Alternatively, you can choose a product with a higher level of phosphorus such as 10-20-10 NPK to boost the quantity and size of your blooms.
Organic fertilizers are available, and these can also help with water retention in the soil. If you have heavy soil, they can help with drainage. Organic fertilizers are composed of natural ingredients such as compost, seaweed extract, bone meal or poultry manure. Because they don’t contain chemicals, organic fertilizer products are generally less strong than their inorganic, chemical alternatives.
Types of Hydrangea Fertilizer to Choose
Fertilizer for hydrangeas is available in liquid, granular or compressed formats. Each type offers certain advantages.
Sometimes liquid fertilizers are already diluted when purchased, but sometimes they are in a concentrated form, so it’s essential to read the directions carefully before use. Liquid fertilizer is either applied to the base of the plant or sprayed on the leaves.
The main benefit of using a liquid fertilizer for your hydrangea shrubs is that the nutrients contained in the product will be quickly released into the soil. These nutrients will be fast and easily absorbed by the plant’s roots and foliage.
This is the most common type of slow-release fertilizer available. The fertilizer granules are enclosed in a coating that dissolves slowly, releasing the nutrients over time. The granules are either sprinkled around the base of the hydrangea plant or sometimes designed to be first dissolved in water.
Compressed Fertilizer Spikes
Even easier to use than granules, these compressed spikes of granular fertilizer contain all the hydrangea food needed by your hydrangeas in a simple-to-use, one-time application. You simply push the spike into the ground around the base of the hydrangea shrub, and it will dissolve over a few months, feeding the plant as it does so.
Although not strictly a fertilizer, many gardeners choose a product that also contains pH-changing qualities. Although white hydrangeas will always bloom white, it is possible to change the color of pink flowering hydrangea bushes to blue. To do this, it is necessary to increase the acidity of the soil. A pH level below 6 will tend to result in blue flowers.
For this reason, it is possible to purchase an acidic fertilizer for your hydrangeas which includes sulfur, gypsum, or aluminum sulfate.
Pest and Fungus Control
Some fertilizer products contain an insecticide to help protect your hydrangea from pests.
Since mildew and fungus can also affect your plant’s health, some fungicide for hydrangea products also contain a chemical that acts as a protector against possible disease.
To further encourage healthy plant growth, some hydrangea fertilizers also include various trace minerals.