Encourage a second flowering, remove dead plant parts or stimulate growth: there are many reasons why summer pruning is so important for many garden plants. What perennials need pruning in summer and why is it necessary?
Why is the summer cut so important?
Fertilizing, watering, a dry and warm winter quarters: What is important for a perennial so that it gets through the winter healthy? Proper care also includes the summer cut. It fulfills several functions at the same time:
bring the plants into the desired shape – very important, especially for potted plants, so that they do not tip over in strong winds.
removes diseased shoots and helps with dry damage.
promotes a second bloom in late summer or fall. Certain cranesbill species, lady’s mantle, lungwort, several comfrey species, and coneflower can benefit from a grooming trim.
makes them more resilient and helps with pest infestation.
prevents self-seeding, in which the plants invest an unnecessary amount of energy. This is recommended for plants such as columbine, magnificent spire or Jacob’s ladder, because they can quickly spread in the garden and crowd out other plants. prepares the perennials for the coming autumn and the cold time before. Especially older plants need regular taper cutsso that they will cast out again.
When is the right time for a summer cut?
The right time for a summer cut depends on the flower. Basically, after the end of the flowering period, you can cut back the perennials in the garden. Provided, however, that the weather cooperates and allows a cut back. Long periods of drought, temperatures above 30 degrees and heat weaken the plants so much that they only recover very slowly after cutting. Direct sunlight can also burn the freshly trimmed perennials. That’s why it’s better to wait with the cut during heat waves.
The best time for a summer pruning is on a cloudy day. Alternatively, you can make the cut late in the afternoon, but if it stays warm and doesn’t rain at night. This gives the plants enough time to recover.
Which perennials do you have to cut in summer?
Basically, most perennials can be pruned in summer without any problems. However, since the different plants also have different care requirements, they are also cut differently. Some require a vigorous pruning, while for others thinning is sufficient.
1. Prune lavender in the summer
The lavender is cut back in early to mid-July. At this point, the first flowering period should already be over. If you notice that the old shoots are becoming woody, then you should take the scissors in your hand and shorten the perennial by two thirds. It is important that you only cut back the old shoots – this year’s wood does not need pruning. Never cut into the old wood, because the lavender will not sprout again.
2. Lupins are only thinned out
The lupins are typical summer perennials and they are cut immediately after flowering. The plants should only be thinned out a little, because the perennials cannot tolerate severe pruning.
3. Remove the faded part of lady’s mantle
The lady’s mantle is gradually cut during the flowering period. The plant is thinned out if necessary and the faded leaves are removed regularly. This prevents the plant from spreading uncontrollably in the garden. Instead of putting an unnecessary amount of energy into seed formation, the lady’s mantle tirelessly forms flowers until late summer.
4. Cut off only the tips of the sack flowers
In the case of the sackcloth, only the side shoots without flowers are snapped off, or even better – cut off. Only at the end of September, when the last flower buds wither and fall off, the plants are shortened by a third.
5. Remount cut at Larkspur
In contrast to the other perennials, the delphinium tolerates and requires a strong pruning after the end of the flowering period. All shoots are usually shortened to 15 cm. The plant sprout vigorously almost immediately afterwards and even flowers for the second time before the end of the season.
6. Which perennials need pruning? Indian nettle
The Indian nettle must be cleaned regularly during the flowering period and the faded – removed. The pruning takes place similar to the delphinium after the end of the flowering period.
7. Encourage the second flowering of daisies
Marguerites are traditionally cut back in July. Varieties that are not hardy must be cut close to the ground before moving into winter quarters. The outdoor plants are not cut as deeply – they can be shortened by two thirds.
8. Phlox doesn’t need pruning in the summer
The faded phlox is regularly removed. The plant does not need heavy pruning in autumn because the above-ground parts of the plant dry out. In midsummer, however, you can shorten and thin out the phlox.
Proper care after pruning supports flowering
Proper care after the summer pruning is crucial – the heavy feeders need extra fertilizer so that they sprout again. And all plants need plenty of watering. Mineral fertilizers strengthen plants and help them recover from pruning.
These plants do not need pruning in the summer
Incidentally, there is also a smaller group of reblooming plants that do not need a summer pruning. These perennials flower again after the end of the first flowering in June. These include, for example, some iris varieties, ornamental sage, noble peony and catnip.
Cutting perennials in summer: the most important things summarized
Most summer perennials require a grooming cut in midsummer. This generally takes place from mid-July to mid-August, although some plants can also be cut back later. The summer pruning promotes growth, rejuvenates the perennials, helps them to have healthy leaves and supports renewed flowering in August. It also makes them more resilient and can help when the plants are infested with pests.
Proper care after the cut is also very important. The plants need an extra portion of fertilizer (a mineral fertilizer is best) and plenty of water so that they can absorb the nutrients better.