The first thing you should aim to do is keep your soil pH higher. To do this, you should first find out what your soil pH already is.

pH, meaning ‘potential of hydrogen’, is a way to express how acidic or alkaline a solution is, 7 being neutral, above this alkaline, and below 7 acidic.

I have a blog all about testing your soil pH. Read it here to find out everything you need to know about the different tests that you can do!

Soil in the UK will typically be at a pH of around 7, so neutral, which is good news for keeping your hydrangeas pink! To encourage pink flowers, you want to aim to keep your soil pH over 6.5, so nearly neutral anyway. Depending on how vivid you want the colour to be, you can adjust the pH accordingly, going up to 7.5 for very pink flowers.

If your soil is naturally quite acidic, you may find it difficult to raise the pH enough to maintain pink flowers. However, a good option is to grow your hydrangeas in pots, to isolate the soil and control its pH more specifically.

Then plant with some alkaline or neutral soil, which you can boost with garden lime if needed.

If you would prefer to plant your hydrangeas straight into your garden beds and borders, you can easily give the soil an alkaline boost with garden lime.

Make sure you check your soil’s specific pH before applying, so you have an idea of how much the pH needs adjusting.

You will also want to be mindful if you have any ericaceous-loving plants like Rhododendrons or Azaleas in the same beds. These plants will not like limey soil, so ensure to keep any lime away from them.

Garden lime is predominantly made up of calcium carbonate, which is ground-up limestone. Other liming materials include calcified seaweed, ground chalk, and ground magnesian limestone. These three will do just as good a job as classic garden lime and can be applied using the same method.

You can easily scatter this across your soil or dig it into the soil to establish it more. You can also do this as a 50/50 split, digging half into the soil, and then scattering the other half over the surface.

Another option is hydrated lime (calcium hydroxide), but you need to be a little more cautious when using this. It is very quick acting but may cause irritation to your skin or eyes, so use protective equipment whilst using.

To maintain this, mulch, and water your soil regularly. Alkaline soil tends to dry out quickly as it is chalkier, so by watering and retaining moisture your plants will be healthier.

If you really want pink hydrangeas, but don’t want to mess around too much with soil pH, there are some varieties that will remain pink regardless of how limey the soil is.

Oakleaf hydrangeas Hydrangea quercifolia, panicle hydrangea Hydrangea paniculata, and smooth hydrangeas Hydrangea arborescens can’t change colour depending on pH. Their blooms will start either white, cream, or dusty pink, so choose a variety that will start and maintain a pink shade.

Hydrangea quercifolia ‘JoAnn’ (Gatsby Pink®) is a wonderful variety, the blooms emerging a pale pink or white, gradually darkening through the season. Their long blooms create a great pop of colour to enjoy.

Hydrangea paniculata ‘Wim’s Red’ is a great choice for changing colour throughout the seasons. The blooms emerge on red stems, starting off pink in the spring, darkening to pink in the summer, then becoming a striking wine-red by the autumn.

A highly popular pink smooth hydrangea is Hydrangea arborescens ‘Pink Annabelle’, which as wonderful round blooms in a delicate shade of pink. They emerge this colour, and retain it until the flowers fade in the autumn.