Feeding raised beds

6x site says

Seed Sowing...
 Prepare your seed bed in the usual way, then sprinkle 1 ounce of 6X Natural Fertiliser per square yard and rake well in. When the seeds are well established a further sprinkling can be applied as needed, to continue vigorous growth.
Transplanting...
 In order that the transplants have a rich food bank to maintain a good, healthy and vigorous growth, rake in 4 to 5 ounces of 6X Natural Fertiliser per square yard about two weeks prior to planting.
 

http://www.6-x.co.uk/directions.htm

Personally, although that seems to say that you can 'sprinkle and sow' - I would use it a couple of weeks before sowing 

Thank you I found a good website which says spread 6X 'at least a week before sewing' so a couple of weeks sounds a good idea. I am going to use this for all my beds growing leafy crops; cabbages, salad, rhubarb and courgettes etc

However it seems as if there is too much nitrogen for root crops in 6X. Do you feed your root crops or just apply a good thick layer of compost a couple of months ahead?

One source suggest a general fertilizer low in nitrogen ( 5-10-10) a fortnight before sewing but i am struggling to find an organic fertilizer with this combination. Another suggestion is to apply a little bonemeal at the time of sewing to provide the seedlings with phosphorus to promote root growth.

What are the secretes to fantastic root veg?

I'd apply a general fertiliser like Blood, Fish and Bone for roots, if you don't want to use 6x