Hardening pot plants kept indoors over winter to outside conditions

Garden Life
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To protect them against cold temperatures, frost-sensitive pot plants are brought into the house before the winter. However, it is now time for a spring atmosphere to take hold again on your patio, and this is also produced through the colourful flowers and leaves of these garden treasures. When the temperatures rise above zero, you should slowly begin to decorate your empty patio once more. However, caution is required, as after a long phase of low light at comparatively warm temperatures in comparison to outside, the plants must first be hardened to the temperature fluctuations, and above all to the daylight.

Why can’t I just put my plant outside?

Pot plants generally can’t cope with temperatures below zero. For this reason, they are frequently placed in protective winter quarters inside homes. When the weather becomes warmer again, the planted pots should be transferred back into the garden as early as possible. However, caution should be exercised here. After winter storage at approximately constant temperatures of 10 °C inside a home, the plants must slowly be hardened to the fluctuating temperatures common over the day in gardens. Plants must also adapt slowly to the wind and the sun’s rays, as otherwise the shock may stunt their growth and cause sunburn on leaves and shoots. In addition, you can still reckon with frost until the middle of May. By getting the plants used to outside conditions after being in their winter quarters, the plant tissue becomes more resistant: harder and more tolerant of the cold.

Making preparations

Before starting to condition your pot plants, they should first be prepared for their new environment. To do this, take them out of the pot and remove a third of the old soil. Before putting the plant back into the fresh soil, the old roots are cut back with shears. Then the plant branches must be proportionally thinned out and trimmed back. In this way, the quantity of the branches is adapted to the quantity of the roots, so that these can also be sufficiently supplied. Then you can begin the conditioning phase to get the plants used to being outdoors. If possible, pot plants should be placed in a shady location during the days when there is no frost. In the evening, if night frost is likely, they should be put back in the house. If the plants are put outside occasionally, these potted treasures can slowly get used to conditions outside once more. This has the advantage that those pot plants which are put back outside quite early will tend to flower earlier, too, in comparison to those which flower very late.

Slow conditioning

The location for pot plant conditioning must be protected from the wind and shade to half-shade. The risk of the warm spring sun for the leaves of plants unused to sun during the winter should not be underestimated. 

The plants must slowly also be conditioned to the sun as well as to the weather outdoors, otherwise the sun may burn their leaves. At the beginning, the plant should stand outside in shade to half-shade. Step by step, you can then provide it with longer periods of sunshine. It is important that the increasing amounts of sunshine are also considered when watering. This means: the more sun the plant receives, the more water it should have. Once the plants have slowly got used to the new weather conditions, including the temperature and the sun’s rays, they can also stay outside during the night as long as there is no frost. However, it is better to fetch in the plants if it should become too cold at night. After the Frost Saints in May – these are the days around the 15th May – the pot plants can then finally be brought outside.