I've interplanted with onions like Miniroots so we'll see if it works, another tip was thin out the carrots in the evening or on an overcast day and as the Scousers have said let them grow to finger size then use them in salads and leave the rest to grow, but will probably take Tims advise and throw a fleece over them, if the carrot fly still get in then its a flame thrower next year. ;D ;D ;D