What happens when seeds are refrigerated before planting?
That might be a good experiment.

I know that before planting bulbs you want to put them in the refrigerator or even the freezer sometimes.  

In fact this process of cold treating seeds has a name: Stratification.  

To paraphrase: some seeds become inactivated at higher temperatures like lettuce and delphinium.  You can place the seeds in medium and put them in the fridge or freezer for a day or two. 

You can see how this makes sense.  The seeds have adapted to start growing when they are freezing because the timing results in the plants breaking ground as early as possible when the temperature is warm enough in the spring. 

A quick search doesn't seem to imply that silverbeet needs to be stratified before planting.  The result might be negative, but there is definitely some good expectation that it makes a difference to some plants.