How to Fertilise Hydrangeas: A Complete Guide

If you’ve ever admired a beautiful garden filled with lush, vibrant hydrangeas, you may have wondered how to achieve such impressive blooms for yourself. And we have the secret to these magnificent flowering shrubs: proper fertilisation. 

Fertilising is an essential part of caring for hydrangea plants, ensuring they receive the nutrients they need to produce those stunning blossoms we all adore. 

In this article, I’ll discuss how to fertilise hydrangeas for maximum impact, from understanding their nutritional needs to expert tips and common mistakes to avoid. 

So, let’s dive in and unlock the secret to beautiful hydrangeas!

Understanding the nutritional needs of hydrangeas

Before we delve into how to fertilise hydrangeas, it’s crucial to understand their nutritional needs. 

Like all living things, hydrangeas require specific nutrients to thrive, including nitrogen (N), phosphorus (P), and potassium (K). 

• Nitrogen promotes healthy foliage growth.
• Phosphorus encourages root development and flowering.
• Potassium plays a vital role in the plant’s overall health, contributing to disease resistance and water regulation.

Hydrangeas also benefit from secondary nutrients and micronutrients such as calcium, magnesium, iron, and manganese. And while these nutrients are naturally present within your garden soil, they often require topping up through fertilisers to ensure your plants receive adequate amounts. 

So, understanding the nutritional needs of your hydrangeas is the first step to beautiful blooms.

When to fertilise hydrangeas for maximum impact

Timing is crucial when it comes to fertilising your hydrangeas. 

For maximum impact, fertilise your plants in early spring, just as they wake up from their winter dormancy. This will provide the nutrients needed for new growth, encouraging a healthy root system. 

And you can boost the plant’s overall health with a second fertiliser application in late spring or early summer. 

Avoid fertilising hydrangeas in late summer or fall, which will promote new growth that may not have time to harden off before winter, leaving the plant vulnerable to cold damage.

How to change the colour of bigleaf hydrangeas

One of the most fascinating aspects of bigleaf hydrangeas (Hydrangea macrophylla) is their ability to change colour based on soil conditions. 

The flower colour of these hydrangeas is influenced by the soil’s pH level and the availability of aluminium. 

How to encourage blue hydrangea blooms

Acidic soils (pH below 6) with plenty of aluminium will produce blue flowers. You can lower the soil’s pH for blue flowers by adding aluminium sulfate or sulfur.

Wait until the plant shows signs of fresh spring growth. Then, mix 7g aluminium sulfate in 4.5 litres of water, and soak the surrounding soil. 

How to produce pink hydrangea blooms

You need to remove the aluminium from the soil for pink blooms, raising the pH and making the earth more alkaline. 

Decrease the aluminium availability in the soil by applying garden lime made from ground limestone. Again, the earlier in spring you do this, the better. 

For best results, grow in a pot

Keep in mind that changing the soil’s pH can take time, and it’s essential to monitor the pH levels to avoid overcorrecting. 

Choosing the right fertiliser for your hydrangeas

A slow-release, granular fertiliser with an N-P-K ratio of 10-10-10 is ideal for most hydrangeas. This will provide a balanced supply of nitrogen, phosphorus, and potassium to support healthy growth and flowering.

When trying to change the colour of bigleaf hydrangeas, choose an acidifying fertiliser for blue blooms or an alkaline fertiliser for pink flowers. These specialised fertilisers provide essential nutrients and help adjust the soil’s pH to encourage the desired colour change. 

Always follow the manufacturer’s instructions for application rates and frequency.

Expert tips on how to fertilise hydrangeas effectively

To fertilise hydrangeas effectively, follow these expert tips:

• Apply the fertiliser evenly around the plant’s drip line, avoiding contact with the trunk or stems.
• Water the fertiliser into the soil thoroughly to help it penetrate the topsoil and reach the plant’s roots.
• Monitor your hydrangeas’ health, and adjust the fertiliser application as needed. Yellowing leaves can indicate a nutrient deficiency, while excessive growth may signal over-fertilisation.
• Test your soil’s pH and nutrient levels periodically to ensure your hydrangeas are receiving the proper balance of nutrients.

Common mistakes to avoid when fertilising hydrangeas

When fertilising hydrangeas, avoid these common mistakes:

• Over-fertilising: Applying too much fertiliser can lead to excessive growth, weak stems, and fewer blooms. Follow the manufacturer’s recommended application rates and adjust as needed based on your plants’ health.
• Fertilising at the wrong time: Fertilising too late in the season can promote tender growth that is susceptible to cold damage. Stick to early spring and late spring or early summer applications for the best results.
• Not “watering in” the fertiliser: Failing to water the fertiliser into the soil can result in a waste of nutrients and potential harm to the plant. Always water in fertilisers thoroughly to ensure they reach the hydrangeas’ roots.

Additional care tips for lush, blooming hydrangeas

In addition to proper fertilisation, other care practices can help ensure your hydrangeas are healthy and produce stunning blooms:

• Prune your hydrangeas at the appropriate time based on their species. Some hydrangeas bloom on old wood. On the other hand, others flower on new growth. Pruning at the wrong time can lead to a lack of blooms for the season.
• Provide consistent moisture, especially during dry spells or hot weather. Hydrangeas prefer moist, well-draining soil and may wilt or suffer from reduced blooming if left too dry.
• Choose a planting location with enough sunlight for your hydrangea variety. Some hydrangeas prefer full sun, while others thrive in partial shade.

FAQs

Unlocking the secrets of beautiful hydrangeas

With the proper knowledge and care, you can unlock the secret to lush, blooming hydrangeas. 

Choose the right fertiliser and apply it at the right time for your particular hydrangea variety to ensure they receive the nutrients they need to thrive. 

And if you have any questions about growing beautiful hydrangeas, don’t hesitate to get in touch!

Thanks for reading.