From DT Brown, I bought 3 types of leek, Japanese leek/salad onion and Broccoli White Eye and White star. Leeks etc in seedbed, broccoli in root trainers. No germination problems (but one of the leeks (apollo F1) and one of the Japanese packets were less than generous).
If anyone knows of another source for Leek Apollo F1 (apart from Marshalls!) please let me know.