There is an old wive’s tale that says “do not sow any seeds six weeks either side of Christmas”. There is certainly some wisdom in this, however with the advent of electricity, glasshouses and polytunnels we are able to push seasonal boundaries further that our forebears were.
A warning on sowing seeds too early: Although it is possible to sow many seeds in January, some crops will only be successful if grown with additional heat and light such as tomatoes, peppers, chillies and aubergines. If not supplied with extra heat and light these crops will have poor germination and the seeds that germinate will produce weak and ‘leggy’ plants. Onions sown in January may need extra heat to germinate but once germinated will be fine at ambient temperature under cover.