4th March 2020, I show results of speeding germination by giving warmth, even in darker parts of a house. You also see my hotbed of fresh manure in the greenhouse.
Some vegetables are multisown in modules, others are sown in trays to prick out. I use module trays rather than blockers, another option. I show and describe different composts ("potting soil") for propagation, including homemade.
If you don't have a garden structure with full daylight, an option is to buy grow lights for raising plants in the house.
My sowing timeline has the best times through a whole year, to sow each different vegetable. https://charlesdowding.co.uk/sowing-t...
Module trays from Containerwise include smaller-celled 77's, which I should have mentioned https://containerwise.co.uk/product/7...

In my online Course 2, three of the 18 lessons are about propagation, with more videos https://charlesdowding.co.uk/product/...

Here on You Tube are two more propagation videos:    • Propagation: germinate, grow and plan...   from April 2018
and    • Propagation 2 first sowings in Februa...   from February 2019

Filmed at Homeacres 4th March by David Adams. Zone 8 climate, and the last frost date in our valley is 15th May. March temperatures average 2C/36F by night and 10.5C/51F by day.