There may be two main reasons for this. The first is that all root vegetables have to be sown where they are to grow. If you sowed them in seed trays and then transplanted them, they will not develop long roots. So always sow them in the vegetable patch and then thin them out as they grow a little larger.
The other reason may be that your soil is actually too rich ! Carrots do not like to be planted in a bed where the soil has had any farmyard manure or poultry manure within the last year. Carrots also do not like any soil which has been treated with nitrogen rish fertilisers within the past year.
So it may be worth trying to grow a crop in a bed next year where no manure or fertiliser has been added. You could however, add in a little non-nitrogen rich fertiliser, just to help them establish.
The other reason may be that your soil is actually too rich ! Carrots do not like to be planted in a bed where the soil has had any farmyard manure or poultry manure within the last year. Carrots also do not like any soil which has been treated with nitrogen rish fertilisers within the past year.
So it may be worth trying to grow a crop in a bed next year where no manure or fertiliser has been added. You could however, add in a little non-nitrogen rich fertiliser, just to help them establish.