Is there a secret for helping dodder seeds to germinate?

You may try dipping the seeds in 10% hydrochloric acid, as we do for gooseberry seeds (overnight).

Check the seeds for viability. Have you tried germination in soil?

You can also have a look at the following

he seed germination of the dodder is promoted by the pretreatments which are effective on the

removal or destruction ef the seed coat by submerging in conz. sulfic acid and by scarification. The

germination of the acid pretreatment is 58% at 5℃ in 15 days and 98% at 30℃ in 2 days. The burial depth

of seeds seems to be effective on the seed germination, paricularly in shallower depth. In the burning

experiment the percentages of the seed germination at a O.5 cm depth are from 2.6% to 5.7% for dormant

seeds and 76% for non-dormant seeds. The process of the germination due to burning can be attributed

to (1) the burning temperatures and heat pretreatment which break the dromancy of seeds and accelerate

the germination at shallower depths and (2) the presence of non-dormant seeds which escape from the

damage of fire at deeper depths and can germinate successfully in the post-fire recovery period.

for more details : http://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/37236/1/12(1)_63-119.pdf

details in: http://www.jstor.org/stable/4043367

Germination of field dodder (Cuscuta campestris Yunck.) was investigated in field and laboratory studies. Germination plots established to simulate field conditions showed a rapid decline in the number of seedlings emerging over a 5-yr period. Less than 10% of the seeds planted emerged. Time of germination was correlated with temperature. The dormancy of seeds buried at various depths was found to be broken by overwintering. Older seeds and those close to the surface germinated best. Scarified seeds did not germinate at 15 C nor at temperatures of 39 C or above. Maximum germination occurred at 30 and 33 C. Scarified seeds planted at various depths failed to emerge from 3.8, 4.0, or 7.6 cm in the three soil types evaluated; the majority emerged from 3 cm or less. Seeds stored outdoors, at 3 to 8 C, or -3 to 0 C declined in dormancy with time compared to seeds stored at 15 to 25 C. 

Dear Kari Caudle, 

Seeds of Cuscuta species suppose to have Physical dormancy. Please read following paper by Jaysuriya et. al.  2008 Annals of Botany; 102(1): 39–48, titled 'Physical Dormancy in Seeds of the Holoparasitic Angiosperm Cuscuta australis (Convolvulaceae, Cuscuteae): Dormancy-breaking Requirements, Anatomy of the Water Gap and Sensitivity Cycling' where they reported 'Seeds of Cuscuta australis germinated >75 % at 35/20 °C and at 25/15 °C after dipping in boiling water for 10 s. Germination percentage was lower after dipping seeds in boiling water for 15 and 20 s. Seeds exposed to 90 °C dry heat for 5–30 min germinated <30 % at 35/20 °C. Seeds stored dry at ambient laboratory temperature for 2 months germinated >65 %, whereas wet-stored seeds germinated to only 8·9 %'

Apply my article method.