When to plant hydrangeas to grow an abundance of long-lasting blooms

Hydrangeas have developed a reputation as popular plants, with their exotic blooms bursting into life from late November through to early February. 

This hardy plant will continue to grow and blossom for many years when kept in the right conditions. 

In order to give hydrangeas the best possible start it is recommended that gardeners plant them at the “best time”, claimed Craig Wilson, horticultural specialist at .

He said: “In the UK, the optimal times for planting hydrangeas are February to April and August to October. 

“These periods offer milder temperatures, which are ideal for helping the plants establish their root systems.” 

While he argued that summer planting can be “successful”, especially during milder spells, it’s important to ensure the plants are well-watered and not exposed to prolonged periods of intense sun.

Once gardeners know when to plant their hydrangeas, they then need to know how to plant them. Luckily, Craig has shared how to do this.

First gardeners need to close the “ideal location”. Hydrangeas need a balance of sun and shade to “thrive”. 

Select a location that receives morning sunlight but is shaded in the afternoon. This ensures the plant isn’t exposed to the harshest midday sun. 

The area should be sheltered from strong winds, as hydrangeas can be sensitive to harsh weather conditions.

The next step is to prepare the soil. These plants prefer rich, moist, yet well-draining soil. Prior to planting, work the soil to a good depth, mixing in plenty of organic matter like compost or well-rotted manure. This improves soil structure, drainage, and nutrient content. 

Testing the soil pH is also beneficial, as it “influences flower colour” – an acidic soil yields blue flowers, while an alkaline soil encourages pink blooms.

After, gardeners can plant their hydrangeas. Start by digging a hole that’s as deep as the root ball of the hydrangea and two to three times wider. This gives the roots room to spread out. 

When placing the plant in the hole, ensure it’s at the same depth as it was in its original container. Craig warned: “Planting too deep can stress the plant, while too shallow planting exposes the roots.”

After positioning the hydrangea, backfill the hole with the soil. Gently firm the soil around the base of the plant and then water thoroughly. This initial watering helps settle the soil around the roots and ensures the plant has enough moisture to start its growth.

Once that’s done, apply a layer of mulch around the base of the hydrangea, extending out to the drip line of the leaves. This helps “maintain soil moisture, keeps the roots cool, and reduces weed competition”. Organic mulches, such as bark chips or leaf mould, are excellent options to use for this as they break down over time, adding nutrients to the soil.

Hydrangeas require consistent moisture to flourish and last long, particularly during their first growing season. The expert instructed: “Water the plant deeply once a week, ensuring the water penetrates the soil to reach the roots.” During hot, dry periods, additional watering may be necessary to prevent wilting.

Feed hydrangeas in early spring with a general-purpose fertiliser to “encourage strong growth and abundant blooms”. Repeat the application mid-summer, especially if the plant is showing signs of slow growth or fewer flowers. However, “avoid over-fertilising”, as this can lead to “lush foliage at the expense of blooms”.

To maintain their plants pruning will be required, however, their needs vary depending on the hydrangea species. Some hydrangeas, like the bigleaf variety, bloom on old wood, so they should be pruned after flowering, typically in late summer. 

Others, like the panicle hydrangea, bloom on new wood and can be pruned in late winter or early spring. Craig highlighted: “Always remove dead or crossing branches to maintain plant health and shape.”