Tithonia seeds benefit from light during germination. Cover them only lightly with vermiculite or similar. I've had good results germinating old seeds by giving them a brief dilute H2O2 treatment, after which they germinated overnight.
It's not too late to start from seeds. I've had them re-seed in mid summer.
Tomorrow when I have more time I will see if I have any seeds left if you are still looking.
Alana
