How to prune buddleja

How to prune buddleja

Follow our expert advice on pruning buddlejas, in this step-by-step guide.

A table displaying which months are best to sow, plant and harvest.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
At its best
At its best

Plant is not at its best in January

Plant is not at its best in February

Plant is not at its best in March

Plant is not at its best in April

Plant is not at its best in May

Plant is not at its best in June

Plant is at its best in July

Plant is at its best in August

Plant is at its best in September

Plant is not at its best in October

Plant is not at its best in November

Plant is not at its best in December

To do
To do

Do not To do in January

Do To do in February

Do To do in March

Do To do in April

Do not To do in May

Do To do in June

Do To do in July

Do not To do in August

Do not To do in September

Do not To do in October

Do not To do in November

Do not To do in December

Varieties of Buddleja davidii can become very tatty if not properly pruned. If you leave buddleja unpruned, the only thing you see at eye level is a twiggy tangle of bare stems, with the blooms held at the tips of the stems, way above head height. They will also grow very large.

Discover 10 buddlejas to grow.

If hard pruned in early spring, the most vigorous varieties will still grow to 3m tall and 2m across by summer, while the smaller forms, such as ‘Nanho Blue’, can be kept to less than 1.5m in height and spread. Prune in mild weather.

There are exceptions to the rule. Buddleja alternifolia and Buddleja globosa bloom on stems made in the previous season, so cutting back in spring would remove the flower buds. Neither should be hard pruned – instead, cut out a selection of the oldest branches completely in midsummer.

Where to buy buddleia online

On the forum: discuss pruning buddleja and other plants in our friendly online community of gardeners

Follow our simple step-by-step advice on pruning buddleja, below.


You Will Need

  • Secateurs
  • Pruning saw
  • Long-handled loppers

Step 1

Start pruning buddleja when it’s coming into growth in early spring. First, trim back the top growth to around half its height using secateurs. This makes it easier to see what you’re doing as you progress, and gives you better access to the base of the plant.

Trimming back the top growth
Trimming back the top growth

Step 2

Cut through the thick woody stems, around 30cm above the ground, using a pair of loppers or a pruning saw. Where possible, prune just above a bud or growing shoot. If you’d like the plant to grow taller than 3m (for example, if it’s at the back of a border), leave the stems up to 60cm long.

Cutting through woody stems
Cutting through woody stems

Step 3

Remove any dead stubs and branches using the pruning saw or loppers. Cut these back flush with the main trunk to minimise the chance of dieback. Also thin out any crossing branches to prevent rubbing, and remove any thin twiggy growth sprouting from the base. Don’t worry that you’re being too brutal, as buddleja is so vigorous that it will quickly re-grow.

Removing dead stems
Removing dead stems

Step 4

Aim to produce a short, strong framework of five to six main branches. It doesn’t matter if you can’t see many green shoots, as buddleja will produce new growth from underneath the bark. Fork lightly around the base to relieve any compaction you’ve caused by walking on the soil, and apply a mulch to the soil surface to retain moisture and suppress weeds.

Removing main branches
Removing main branches

Pruning in May

You can encourage buddlejas to flower later in the season, by cutting them down to the ground in May. This benefits butterflies such as the small tortoiseshell.