Hydrangea Care Guide: How to Grow Hydrangeas

Hydrangea Care

Hydrangeas are generally easy to grow and care for. The different varieties do need slightly different conditions, so check the individual plant for more detailed instructions on care.

Light Requirements

Most hydrangeas prefer to be located in full sun or partial shade. However, they do not like exceptionally hot, arid conditions so if your garden receives a lot of sun they will prefer to be a little protected from the worst of the heat.

Water Requirements

Hydrangeas usually need a deep watering about once a week. In very dry weather they may need even more. It is best to give them a thorough watering rather than a light sprinkling every day. Water your plants at the base rather than on the leaves to help prevent too much humidity which can encourage fungus to thrive. Water early in the day to allow any moisture on the leaves to evaporate.

The American varieties are more drought tolerant than the Asian ones.

Soil Requirements

Hydrangeas can grow in a wide range of soils including acid and alkaline types. However, the Asian varieties need acid soil in order to flower. All types prefer a rich soil that is moist but free draining. If planted in dry soil they will need more watering. If your soil is poor, then adding extra compost and organic matter can help them thrive.

Fertiliser Requirements

Fertilise your shrub in early spring to support new growth and plentiful blooms. You can use an organic soil improver or a slow release shrub fertilizer. You may like to repeat this in summer, depending on your soil conditions. However, do not fertilise after August as this can encourage new growth that will be too tender to survive harsh winter weather. There are special hydrangea fertilisers available, but these are not really necessary.

Do not be tempted to over fertilise your shrub. If your plant is looking sickly it is important to find out exactly what is wrong rather than just feeding it more. Over fertilising can cause more problems for an already stressed plant.

Hydrangeas also benefit from an application of liquid iron every two years. This will keep the leaves nice and green and healthy. This is particularly important for the Asian varieties.

If you are growing a pink or blue variety, you can keep the colour you want by adding small quantities of either sulphur or lime to the soil. Lime will result in pink blooms and sulphur will turn them blue. This will not happen overnight, so you will have to be patient.

Planting

You should plant your hydrangea in spring once all threat of frost has passed. Dig a hole twice the size of the rootball and add some soil improver or compost. Plant level with the surrounding soil and water in well.

Add a layer of mulch to help retain moisture and suppress weeds. Do not let the mulch touch the base of the plant to reduce the risk of rotting.

If you should need to move your shrub for any reason this should be done in autumn or winter when the plant is dormant. Try to make sure you get the whole rootball and replant immediately to avoid stress to the plant.

Maintenance

To keep your hydrangea looking at its best you should dead-head whenever the blooms become spent.

This will divert the plant’s energy to new growth and blooms. The correct way to deadhead your hydrangea depends on the time of year. Before August spent blooms should be cut back to a larger branch on which new buds are present. After August, there will be buds on the stems in preparation for next year’s blooms, so you should cut back only to these. Cutting back further at this time of year may result in a loss of flowers the flowing year.

In winter it is sometimes appropriate to leave the spent blossoms on the plant. This is because the new buds for next years growth are just below the old blossoms so leaving them on can provide protection for these tender buds over winter.

Container Grown Hydrangea

Hydrangeas are often given as gifts in small pots but unless re-potted these will rarely last more than a few weeks. Ideally, you need to re-pot hydrangea into a container several inches larger than the one it came in to give its roots access to plenty of moisture and nutrients. Ensure the pot has plenty of drainage holes so that your plant doesn’t sit in water. Leave a few inches between the potting compost and the rim of the pot.

This will enable you to water it well without water and soil spilling out of the pot. Hydrangeas like plenty of sun, however, they do not like to dry out. For this reason, it’s best to put your container-grown plant in a place that gets morning sun, but a little shade in the hottest part of the day.

Your container grown hydrangea may need some protection in winter. You can place it in a cold greenhouse or protect it with fleece. Remember not to let it dry out over winter. It will not need much water, but it will require some.

Repotting

If your hydrangea is not a dwarf or compact variety it may need repotting again in time, or alternatively, you can prune it to the size you want. Make sure you prune it at the right time of year for the variety or you may lose the next years blooms.

Pruning Advice

The different varieties of Hydrangea have different pruning needs.

The most common types, the mopheads and lacecaps of the H. macrophylla variety, usually need pruning after blooming in late summer.

Paniculata should be pruned in late water or early spring, though the spent flower heads can be cut as they die back.

Arborescens can be cut back to flower buds in early spring.

The oakleaf varieties are best pruned in early spring.