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Some like it cold – cold germinators

Garden Life
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Have you ever planted a number of seeds in spring, only to have limited success come the summer? A possible reason for that may be that these seeds are so-called 'cold germinators'. The following guide will give you tips on the considerations to take when maintaining and planting, but also on what happens inside the seeds.

Cold germinators originate from cold, wintery areas. To survive the winter, the seeds have developed a hard, thick shell that protects against the elements. When frosty temperatures arrive, the plant decomposes a substance which suppresses the germination.

Cold and moisture

Cold germinators need cold temperatures in order for their seeds to begin germination. This germination depends on the interplay of precisely two different conditions;

Firstly, there must be sufficient moisture and the correct temperature to enable the seed to swell out. Secondly, for a certain period, temperatures should be between -4 and 4 degrees.

These two requirements guarantee that the seed doesn't germinate too early and more importantly, that it doesn't freeze. Normally the seeds need cold temperatures for 4-6 weeks to germinate, but they must lie in moist soil during this period.

Conditions of growth

You can begin planting the cold germinator seeds from autumn. Preferably choose a place where the variations in temperature are not too extreme and where moisture can be easily controlled. Ensure there is no frost outside, otherwise you cannot sow the seeds.

The refrigerator as substitute

If you delay planting for too long or you experience a mild winter, you can utilise a refrigerator as a cold replacement to simulate an artificial winter. Follow this by adding a piece of absorbent cotton into the seed bowl and distribute the seeds amongst the cotton. Cover this with a thin layer of soil and slightly moisten so the soil and the cotton are wet, then place into a plastic bag. How long exactly they have to be in the refrigerator is dependent on the seed type. This can be for as little as two weeks or up to several months in the refrigerator at four degrees or less to break the sprout inhibition. Take care to pay attention as temperatures that are too low can destroy the seeds. Afterwards remove it from the plastic bag and sow it into a vessel with potting compost. Keep it warm at a minimum temperature of 12 degrees so the seeds begin to germinate.

A few examples of cold germinators:

Lady's mantle, lily, pansy, peony, poppy, primrose, ranunculus, sage