Hatching experiments were conducted on sediment samples collected on seven cruises between March 2002 and February 2003, at four stations near Helgoland (54°11′N, 7°53′E). Samples were incubated for up to 12 months and examined weekly for calanoid copepod nauplii. 12807 nauplii hatched in total. Of these 36.43% were stage N1 (pooled), 44.08% were Temora longicornis (stage N2 and older), and 17.96% were Centropages hamatus (stage N2 and older). Some Acartia spp. and an unidentified species were found, too. Hatching varied significantly between sampling dates. At three stations, counts of all nauplii peaked in samples taken in April, while at one station the maximum was recorded in the sample collected in October. The seasonal pattern of hatching was similar in T. longicornis and C. hamatus. In March, April, October and February numbers of all nauplii were initially low, but increased over the following 2–3 weeks. In June, August and December, however, average numbers were comparatively high at first, but declined thereafter. In three of the four samples that were incubated for 12 months nauplii hatched from the sediment for the entire experimental period. Temora longicornis and C. hamatus displayed clearly distinct patterns of hatching in these long-term incubations.