How to sow seeds that need cold to germinate outdoors – a quick guide
1. Why some seeds need cold to germinate
Some plants have seeds that need to go through a cold phase – also known as cold stratification – before they can germinate. These seeds contain special substances to inhibit germination that can only be broken down by the effect of low temperatures over a period of several weeks. Only after this cold stimulus are the seeds ready to sprout when temperatures start to rise in spring. This adaptation ensures that they don’t germinate too early in autumn and then fail due to frost damage.
2. The best time to sow
The perfect time for sowing seeds that need a cold phase is late autumn through to early winter, generally between November and January when temperatures are low enough to provide the necessary cold stimulus. This gives the seeds enough time to go through the cold phase during winter, so that they can germinate perfectly when temperatures start to rise in spring.
