When to Prune Buddleia (Butterfly Bush) & How to Do It

• Prune your buddleia in early spring by cutting all branches at a 45-degree angle with pruning shears until they’re 1 foot (30 cm) tall.
• Remove old or diseased branches at the root by digging them up with a shovel. This will eliminate overcrowding and help your buddleia to produce new blooms.
• Deadhead dead or dying buddleia flowers during or after blooming season by cutting them directly under the bloom at a 45-degree angle using pruning shears.

Cutting Back Buddleia

Prune most buddleia varieties in early spring. The first month of spring is typically the recommended time for pruning; however, when to prune your buddleia ultimately depends on where you live. Severe frost, present in late spring in some areas, can cause damage to buddleia. As a rule of thumb, wait until the weather's been consistently warm and above freezing for a few weeks before pruning. Hold off on pruning if you see freezing temperatures or snow in your 10-day forecast. Waiting until later in the summer or fall to prune can be deadly for the buddleia. If new growths do not harden before winter, the cold will kill them, resulting in a dead plant the next spring.

Prune alternifolia and globosa buddleia varieties in midsummer. These buddleia varieties flower on the previous season's growth (old branches), so pruning in spring would remove flower buds. Instead, cut back the branches of these varieties at a 45-degree angle by 1/5th-1/3rd in mid to late summer after flowering. Always leave 1-2 sets of buds on the branches.

Cut all branches to 1 foot (30 cm) tall using pruning shears. Even if there is no sign of rot or damage to existing branches, cut all of the branches above 2-3 sets of buds at a 45-degree angle using pruning shears or a pruning saw in early spring. Ensure the final height of the branch is no less than 1 foot (30 cm) tall. These thinning cuts will stimulate bloom production, making for a spectacular flowering come late summer and fall. Don't be alarmed by how much you cut from the plant, as intense pruning helps the buddleia grow new flowers when the rainy season passes.

Remove old, diseased branches at the root with a shovel. Buddleias can become stifled and produce fewer blooms if too many branches sprout. If your buddleia bush is crowded, use a shovel to dig out the unnecessary branches at their roots. This will prevent them from re-blooming in the coming season. Old stems typically have peeling, gray-brown bark, while new branches are green. Diseased buddleia branches will appear misshapen or have yellow/brown growth. Butterfly bushes are also prone to mildew which will present as furry patches on the bark and foliage.

Deadhead spent blooms throughout the flowering season. Use your pruning shears to cut directly under the bloom at a 45-degree angle to deadhead dead or dying buddleia blooms. Periodically deadheading your beautiful buddleia bush throughout the summer months will help keep your plant trim and tidy while encouraging new growth.

Encouraging Bloom Production

Spread 6 inches (15 cm) of mulch around the buddleia in early spring. Spreading mulch or compost around the stump of your buddleia plant will help it retain moisture and fight off unwanted weeds. Add about 6 inches (15 cm) of mulch or compost along the stumps of the plant and get excited for the gorgeous blooms that are soon to come thanks to your hard work and tender loving care.

Water your buddleias once a week. While buddleias are great at tolerating drought, they prefer well-drained, not bone-dry soil. Watering your buddleia around once a week ensures that young branches get the attention they need to mature and produce the best blooms around, come summertime. Regularly check the soil surrounding the plant to ensure it's damp. If it feels dry, water the soil until it moistens slightly. Water the buddleia twice a week or more if you live in an area experiencing a drought or sweltering temperatures.

Plant new buddleias 5-10 feet (1-3 m) away from existing plants. Buddleias are extremely fast-growing and branch out in stems. If you decide to plant more buddleias, keep the new plants at least 5-10 feet (1-3 m) away from existing plants to ensure your lovely buddleias have adequate space to thrive.