I don't put much into a float test to determine viability. I've had as many floaters as sinkers germinate. Are the seeds dark, hard and plump? If so I'd go ahead and plant them. If they don't look ripe I'd say something to whoever you got them from. I don't know what Rubra seeds look like but the ripe seeds from a few of my passiflora varieties are really little.
Karyn

I'm with Karyn.. I don't put much credence in the theory of floating seeds.. I put some Passi aurantia in to soak today I had 2 that floated in the beginning but after a couple of hrs. they sunk.. I had 3 Nag Banana seeds and all three floated and now 2 of them are up and growing..
Best of luck with them!!! Chena

P. rubra's a Decaloba. Decalobas are known for having some of the smallest seeds of any passiflora.

Thx yal I feel better the seeds look really good hope they will sprout I only was able to get 10 seeds so I sure hope 1 will sprout .Every one of the seeds was a floater and wow they are so tiny.Well wish me luck hope to show yal some rubra sprout pics soon hehe.I dont have the best luck with passiflora seeds they take so long im spoiled after morning glorys they sprout in a few days .

I have some that sprouted within a few days, others that took over a month and some I'm still waiting on. I've heard that some passies can take many months so I haven't given up but hope I remember where I planted them! I recently reused some soil that I thought was clean for asclepias seeds and now have pipevines coming up in it. I've only been able to germinate my passiflora seeds with bottom heat. Good luck.
Karyn