Pruning a butterfly bush: when and how? | manual

The butterfly bush is one of those shrubs in the garden that benefit from regular pruning in many ways. It stays more vital, develops more flowers and blooms longer. Even if the gardening work plan is packed with all sorts of things that still need to be done. You should not do without pruning Buddleja davidii. With the right instructions, you will also become more and more familiar with the different types of cuts, so that it is done quickly.

Cut for flowering

This butterfly magnet, originally from China, forms its flower buds in the year of flowering. This only happens on shoots that have newly developed immediately after the cut.

• each new shoot blossoms from July to October
• depending on the variety in white, pink, red or violet
• first at the tips of the shoots
• later on the smaller side shoots.
• old shoots, on the other hand, do not form a single flower

In order to bring about a high number of new shoots, you have to cut heavily on Buddleja davidii.

effect on the crown

However, the harder the cutting, the more the butterfly bush loses its shape. It will be a few weeks before Buddleja davidii becomes magnificent again with new shoots. Anyone who has planted the butterfly bush as a privacy screen must therefore carefully consider how much they are removing from the plant. Here, a low key pruning would be a middle ground that both provides blooms and maintains some privacy.

Heavy pruning also has another disadvantage: Over time, it leads to dense whorls of branches. It has to be cleared out again and again. The types of cuts described below are therefore only the framework. You have to determine the size of the cut yourself. What takes precedence? The flower, the crown structure or both?

The optimal time

Although the summer lilac survives the winter outdoors, it is sensitive to frost. Open interfaces, such as those created after pruning, make the butterfly bush more vulnerable in this regard. This is why we wait until the big frosts are over before weeding this plant.

• let the cold season pass
• only divorce in the spring
• Mid-February is the ideal time
• the pruning should be completed by the end of February
• Timing applies equally to all types of cuts
• the later the pruning, the later the flowering

Buddleja davidii would also cope with a cut at a later date. However, severe pruning of shrubs after March 1st is not permitted in this country. This is to protect nesting birds. Only light grooming cuts are allowed.

Appropriate tool

Even if this “butterfly meeting place” can easily grow 2 to 3 meters high. Rarely do the branches of Buddleja davidii become very thick, as the crown usually forms from the newest shoots. You don’t need a saw to shorten them. Pruning shears are sufficient for the scaffolding shoots, while you can also remove the side shoots with pruning shears. However, you should always disinfect the cutting tool before and after use. In order to leave behind clean cuts, the blades should also be sharpened regularly.

With wilted flowers at the tips of the shoots, some specimens will be perched out of reach. A stable ladder is therefore indispensable for larger shrubs. Pulling down on the shoots can easily cause them to snap off.

Divide on pegs

When branches are removed from buddleia, it is never done directly at the base. Cones about 10 cm long are always left standing. It does not matter whether it is a skeletal or side branch. New shoots will appear around the cone in summer. If the knots are removed without the tenon, the cut will dry back into the old wood. The hoped-for new shoots do not appear.

The types of cuts

Depending on the life phase and condition of the butterfly bush, there are three possible types of pruning waiting for it:

• education cut
• maintenance cut
• taper cut

Educational cuts are necessary in the first years of life in order to build up a branch structure. A rejuvenation pruning, on the other hand, allows senile shrubs to bloom more luxuriantly. It is mainly due when there has been no cutting at all for a long time. What comes up every year in spring is the maintenance cut. Below you will find the appropriate instructions for each type of cut.

education cut

Buddleja davidii is raised with only a short framework. Older shoots lose much of their winter hardiness over time. That is why they should be removed after a few years. The cut stimulates the formation of new bottom shoots. Here are the instructions in detail:

1. In the first three years of life, only leave three to five strong bottom shoots as the framework. They should face outwards and be evenly spaced.
2. Remove all superfluous and weak ground shoots close to the ground.
3. Shorten the scaffolding shoots to at least 30 cm.
4. Extend the skeleton shoots by 15-20 cm annually for the next 3-4 years.
5. Cut back all side shoots from the previous year. Only short cones with 2-4 buds should remain.
6. Cut back one-year-old young shoots to 30 cm.

maintenance cut

Prune older summer lilacs that already have branches in spring every year. The harder you cut back, the more new shoots and flowers will follow. But at the same time you intervene strongly in crown construction. Fortunately, there is a certain amount of leeway when it comes to maintenance cuts. It can be cut both strongly and carefully.

1. The butterfly bush should be cut back by about half or at least to 1 m. Even shorter, up to tenons, is possible. Before using the scissors, determine the extent to which you want to cut your butterfly bush.
2. Cut older shoots to the ground. Leave only 10 cm long cones.
3. Shorten young bottom shoots – if there are any – to 30 cm.
4. Also shorten all side shoots of the scaffolding. Only cones with 2-4 buds may remain.

Ideally, the result of this cut is a frame that is limited in height and only has short pegs.

Remove faded

The annual maintenance pruning of Buddleja davidii can also include the removal of faded flowers. Pruning begins as soon as the first flowers have faded. The instructions for this are very simple:

• Cut off faded panicles promptly
• in each case to the next side shoot
• this prevents energy-intensive seed formation
• new flowers follow on the side shoots
• they benefit from the energy savings
• consequently they get bigger

If the butterfly bush is still very vital, it is definitely worthwhile to keep cleaning it out until late summer. This allows you to get maximum flowering performance. Incidentally, some varieties seed themselves heavily. For this reason alone, seed formation should be prevented by cutting off wilted flowers. If this work is too much for you, you can fall back on a sterile variety such as ‘Lochinch’ or ‘Butterfly’ for new plantings.

taper cut

Butterfly bushes that regularly feel the scissors do not age. Provided, of course, that the annual maintenance cuts are carried out professionally. Only then will old shoots give way in time in favor of young shoots. If Buddleja davidii has not been pruned at all for several years in a row, its flowering capacity will decrease noticeably. Only a radical makeover cut can bring them back to life. These are the key points of the guide:

• leave existing young ground shoots
• Divert old scaffolding shoots that have vital side shoots
• to an outward-pointing side shoot
• shorten this side shoot to 30 cm
• Cut back remaining side shoots to 2-4 buds
• remove all other old scaffold shoots close to the ground
• only leave 10 cm cones
• wait and see whether new shoots form on the cone

These instructions are not a guarantee of success. It can happen that a butterfly bush that is too old can no longer sprout new shoots after pruning. Then his existence is unfortunately over.

Protect from snow masses

Regularly trimming and removing the old branches will constantly produce new branches on the butterfly bush. These can sometimes be very long, but remain comparatively thin. They break easily under large amounts of snow. However, breaking off – especially the scaffolding branches – should be prevented.

• Tie branches together with soft string
• those made of natural materials are ideal
• tying it to a peg is also useful
• especially recommended in snowy areas