Our initial seed bed is literally a bed with mattress removed and replaced with a layer of plastic, insulating bubble wrap, sand and our heating cable/mat.
This bed holds only about 9 seed trays but that is still 2,700 seedlings at one time (over 30,000 flowers)....When it starts getting a little warmer, we also make a similar seed bed outside in the propagation greenhouse..
Some of the first flower seedlings are ready for the next stage; transplanting into larger soil-blocks. This is when we really start using a lot of space as each of the 300 mini-blocks in the initial trays is transplanted into trays of just 36 larger soil-blocks... so 1 tray turns into 8.....
Best get making those soil-blocks.