I just posted a photo showing how I have set up my containers on my heat mat in the thread about your double pod. Here it is again...

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My heat mat is just a cheap one, and I think it gets a bit too warm to keep the seed tray directly in contact with it... so I created a buffer zone using a plastic lid... it dissipates some heat, allowing the water to stay at a nice warm, bot not too warm, temperature.

Good luck with your seeds, Wildebloem! Keep us posted!

A number of the seeds had roots in 5 days. I was impressed at the speed.

The first leaves showed at 14 days. The seeds are still in the water, still with just the one leaf each on those that sprouted. Any suggestions when or at which stage to plant them in soil?

I'm not sure at what day I pulled mine out of the water and planted them, but you can kind of see by my photos above that the sprouts each had a decent leaf when planted. I didn't want them sitting in the water any longer than necessary. Once it looked like no other seeds in the batch would sprout, I planted the ones that did sprout and dumped the rest.

Out they come then. I bought a tray with individual cells and a cover, and the entire thing will go on a heating mat.

I leave them in the water rather long: Then I transplant them in fertile soil when the second root starts showing.( they're so big then they're easy to handle: just take the leave betweeen your fingers.
At first I keep the soil rather wet as the roots are used to that. They keep on growing ... ( if by chance the first root is slightly damaged: the second-one is there to take over !)
Dependent of the temperature some chamomille tea is added to the water to prevent the development of funghi.
Usually I have roots on most of the seeds in 2 weeks time.

After I plant my sprouts in soil, I keep them covered for a greenhouse effect, and they stay on the heat mat. So far, so good.

I had really good luck last year planting perennial seeds outdoors in flats... they stayed on a concrete slab in front of the garage, which faces east. I planted the seeds in early May. Anyway... I was thinking that I might try planting some hippi seeds this way in May of this year! I would use a regular 72 cell flat, fill it with good medium, and plant some of my seeds from this past season... I think they stand a good chance of germinating and growing up strong out in the sun and breeze...

I have kept aside a number of the seeds from the double pod, just in case. I wonder how long they remain viable? But then, it is probably best to let them germinate as close to the time they normally would as possible.

Jaap, I noticed a number of sources suggest (trans)planting at two leaves - when the second root shows, is there still just the one leaf?

Also, you mention the chamomile tea addition is dependent on temperature? When/how do you use it?

Wildebloem - did those sources mean leaving them in the water until there are two leaves? Or were the seeds started directly in some sort of medium?

I'm not sure how long it would take for a second leaf to develop, but I don't think it would be healthy for my sprouts due to the fact that the water gets icky after a while... and changing the water frequently disturbs the sprouts...

I could buy some bottled water to use... spring water, or I could collect some rain water... I wonder if that would make a difference?

I've also read that some people add a little peroxide or chamomile tea to the water as an anti-fungal. I can't remember how much of what to add, though...

You know, Jodi, that is a good question. I do not remember if the notes referred to seeds grown in water or soil. And of course I cannot find a single reference right now.

I think the best thing I can do is plant them now: in addition to our usual lives, we are in the final stages of planning a new house and with so much attention diverted elsewhere, these poor seeds will probably end up blooming in their little puddles.

Yes, most of the seedlings have one leaf when I transplant them, length about 5 - 6 cm.
The seedlings I grow in my study - as most of my plants: my wife only wants them in the livingroom when flowering (!)- which most of the time is below living-room-temperature ( no double glazing in my study ).
When the temperature is not too high the chance of funghi devellopping is not too great: I don't make - and add - chamomile tea to the germinating-water; when the temps are higher though .... I do !
I almost never need to change or refresh the water: I only add some when the level decreases too much through evaporation