waist

i have 13 litres of seed compost & 10 litre of perlite mixed is there anything i can add to this to substain an auto through veg till i start bloom nutes as i have only used a handfull of the mix for 2 seed pots & dont want to waist 20 litres or so ( compost food 3 week)
cheers fil7

ok guys for potting on still using seedling soil after 3 week what would you add to take you till bloom
cheers fil7