The gentian bush (Lycianthes rantonnetii) is very popular despite the high maintenance requirements. In autumn, it needs special measures for overwintering so that it gets through the winter well and blooms vigorously again the following year.

Gentian shrub not hardy

A gentian bush, also called potato tree and potato flower, is sensitive to frost and therefore not hardy. If the temperatures drop below seven degrees Celsius, it increasingly loses energy and becomes weaker. Brief sub-zero temperatures are enough to cause severe frostbite, which can cost the nightshade its life. Above all, gentian bushes cultivated in tubs are very endangered because the cold gets unfiltered through the thin tub walls and bottom. Therefore, the following applies: a Lycianthes rantonnetii should always be overwintered in a frost-free location in a suitable winter quarters.

In time for the winter quarters

Weather forecasts are not 100 percent reliable. In order to keep the risk of temperatures that are too low, especially at night, moving to the winter quarters should take place at the latest when the daytime temperatures are constant at around ten degrees Celsius. This is usually the case at the end of September.

Ideal winter quarters

Moving to winter quarters only makes sense if it meets the requirements of the gentian bush. The winter quarters should therefore meet the following conditions:

  • Ambient temperatures: between eight and ten degrees Celsius
  • At no time should the temperature fall below seven degrees Celsius
  • Light conditions: bright – tolerates darker locations, but loses all leaves as a result and flowering begins later
  • Ventilation option required for oxygen exchange and prevention of pest infestation
  • Absolutely draught-free location
  • Fixed location without (constant) moving at a location with changing conditions
  • Examples of ideal locations: unheated conservatories, stairwells, basement rooms, gazebos

Preparation for wintering

Overwintering in a suitable winter quarters without complications and damage only works if some preparations are made on the gentian bush or if various measures are omitted:

  • Control and, if necessary, control of pests
  • Cut back (see under “cutting”)
  • Do the last fertilization at the beginning of September at the latest (optimal: gentian fertilizer – strengthens resistance)
  • Let the sodden soil dry outside (put it away from the rain in good time so that the soil can dry, otherwise there is a risk of rotting)

To cut

Regardless of whether the potato tree is cultivated in a bucket or planted in the garden bed, a slight pruning is possible about three to four weeks before moving into the winter quarters. Cutting should not be done later, because it means a burden for the nightshade plant, with which it should not go into the winter phase. Two to three weeks are enough for the plant to recover.

However, only dried-up parts of the plant are removed and overhanging shoots are cut off at the tips. Pruning should be kept to a minimum so as not to severely limit bud formation. Unwanted side shoots can also be removed from tall trees.

Gentian bushes in the garden bed

In the garden bed, surrounded by dense layers of soil, the cold/frost is less likely to reach the roots. However, it hits the above-ground parts of the plant and is just as destructive there as with potted plants. For this reason, bedding gentian bushes are just as little hardy as tub specimens. Around the end of September they have to relocate to the warmer winter quarters and are to be dug up accordingly and transplanted into suitable containers. You should pay attention to a few details:

  • Be careful when planting out: do not damage the roots
  • Choose a sufficiently large tub/pot – roots must not snap off
  • Container must have water drainage hole
  • Use fresh, loose, humus-rich and structurally stable substrate
  • Lay drainage out of gravel, potsherds or quartz sand before backfilling (layer about two centimeters high)
  • Water only moderately after transplanting
Tip: If you put gentian bushes in the garden bed, you can do this together with the pot. This is simply placed in the planting hole and simply removed again in autumn for the winter. In this way, the nightshade plant is not additionally burdened with cutting because it remains in the usual soil.

Gentian bushes in tubs

In pots, falling temperatures reach the roots faster and more intensively. Therefore, it is particularly advisable to look at the upcoming weather conditions so that the potato tree is not surprised by the cold and can be brought in in time for the winter. Due to the immense growth power, the conversion of tub plants usually proves to be difficult. It is easier to use roller tubs or small trolleys that are placed under the tubs and make transport much easier. It is also important to ensure that the substrate is kept loose so that there is no compaction and water can flow through easily.

casting instructions

Although the winter with low temperatures reduces the water requirement, watering should not be completely stopped during the winter. Gentian bushes do not fall into a “motionless” hibernation, but only into a hibernation with reduced metabolic activity. The soil must therefore not dry out completely during the winter period in order to keep the metabolic system running and the plant alive. Since no moisture evaporates due to the cold and a lot of rain causes increased humidity, watering is only necessary occasionally. Check the soil for moisture levels at least once a week so you don’t miss the right time. The best way to do this is with the thumb test:

  • Thumb can easily be pressed deeper than two centimeters into the soil: no need for watering
  • Thumb lets press no less than two centimeters into soil: water lightly
Note: Gentian bushes do not tolerate strong temperature differences caused by watering with warm or icy-cold water. Only water that roughly corresponds to the temperature of the winter quarters is used.

end hibernation

The gentian bush can only go back outdoors once the frost is over. This is the case at the latest after the Ice Saints in mid-May. But before that, a gentian tree needs to get used to the fresh air and new outdoor conditions.


  • From the beginning/mid-April and temperatures above ten degrees, put them outside for two to three hours, sheltered from the wind
  • Increase your stay to five to six hours by the end of April/beginning of May
  • Choose a bright location
  • Likewise, gradually expose to warm rays of sunshine
  • If temperatures drop below ten degrees, bring the plant in immediately
  • Planting in the bed after the ice saints at the earliest
  • Increase/adjust the amount of water from February/March

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