The decorative lamp cleaner grass usually has to be cut once a year so that it does not lose its beautiful appearance. The following article explains how this is ideally done and when is the best time to do so.

Ideal time

Pennisetum pruning is done once a year. Autumn should not be chosen as the time for plants that have been cultivated outdoors in the garden bed. Pruning should always be done in spring. For this purpose, the time before the new shoot must be adjusted:

  • after the last frosty days
  • no earlier than the end of March
  • no later than April
Note: Why you shouldn’t cut the pennisetum grass before winter is quickly explained. With short stalks there is always an increased risk that they will rot if cultivated outdoors in winter when the climate is damp and wet. This can spread to the roots and then lead to the death of the entire plant.


Since the lamp cleaning grass in the garden bed is not hardy, it is only cut in the spring. Because the long stalks and remaining ears are also needed as winter protection. Therefore, these are loosely tied together in autumn to protect the roots from cold and wet. The same procedure is also used for plants that overwinter in the bucket outdoors:

  • provide the appropriate tool
  • remove the applied bark mulch and brushwood
  • cut ribbon
Note: A suitable tool is normal pruning shears, such as those used for cutting roses. Even if the scissors are removed from the garden shed clean, you should clean and disinfect them again before cutting them back. Because viruses, fungi or bacteria can also have settled here during storage.

To cut

There are different types of lamp cleaning grass in different heights, which can be between 60 and 120 centimeters in length. Depending on the breeding form, the length of the stalks should also be different after the cut. The plants can be cultivated all year round in the garden bed or in a bucket in the garden:

  • Cut off all ears close to the ground
  • all blades of grass in tall varieties to 10 cm
  • in low varieties to 5 cm

When cutting, care should be taken to ensure that new, healthy shoots can form from the rootstock. Therefore, there must be enough light between the cut stalks and enough space for new shoots.

Tip: When you cut the pennisetum, don’t pay so much attention to how deep you cut, it doesn’t matter exactly to the centimeter, as the cut stalks do not bring new shoots. It is more important that the new shoots, which are formed directly in the rootstock, have enough space and air to develop.

Further care

After the pruning carried out in spring, Pennisetum setaceum needs further care in order to be able to sprout again and to show the first flowers again in July/August and the second flowers in September/October:

  • Water well when dry
  • last application of fertilizer should have been in August
  • now well supplied with fertilizer
Note: You should also make sure that the plants get enough water during dry periods over the winter. Even if bark mulch has been spread, which also keeps the soil moist, strong winter sunshine can cause the plants to dry out if they do not receive enough water. However, you should only water on frost-free days.

Cultivated in tubs

The situation is completely different for plants that have been cultivated in tubs and move to a frost-free location in winter. Because here the stalks and ears should be cut before moving to the winter quarters, since no winter protection of the roots by the stalks is necessary:

  • cut back to ground level
  • between five and ten centimeters in height
  • depends on the height and type of plant
  • before the first frost
  • overwinter in a dark, frost-free place
  • Garage, staircase or basement
  • avoid direct sunlight
  • to March, April in winter quarters

The plant in the bucket, which was cut back in autumn, is brought outside again with the first warm days. However, cool, frosty nights should be avoided. Since the rootstock is still exposed when it is cut back in autumn, it could still be damaged by frost in spring.

Tip: The first care for the lamp cleaning grass in the bucket should be done immediately after the bucket has been pulled outside again. However, immediately after the cut in autumn you should leave the plant alone.

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