Well, I've never grown Lobelia but after doing a little web searching it appears that the Riviera Rose is a tender perennial that's usually grown as an annual.

Although not always necessary, cold/moist stratification is usually helpful in regard to seed germination of perennials. Personally, I cold stratify all my perennial seed in the refrigerator. Even if it's not absolutely necessary, it can't hurt anything and usually seems to be very helpful.

Some websites say that cold stratification is necessary in order for Riviera Rose seeds to break dormancy (others of course disagree.
B & T World Seeds say that "Lobelia erinus Riviera Rose seeds need to be overwintered before they will germinate".

In your post, you didn't mention anything about stratifying the seeds before sowing them. You may want to do that the next time just to see if it helps. As I said, it sure can't hurt anything.

Art

I grow the standard "Fountain Blue" Lobelia from seed every year with no fuss. The riviera rose must be more particular. The one site I checked said average germination time is 20 days at 70 degrees. Is it possible that you are giving them to much heat?

Are the seeds pelleted or raw? You say you are using heat/light, is it possible you are cooking the seeds? Are they drying out?

Last year I grew Lobelia Riveria Blue, and they were also very difficult to germinate, and I had been growing Cascade blue ones without fail for a couple of years (both commercial and collected seeds). I,too, did a 2nd sowing because the first sowing had dismal germination. The germination rate was still very low, and the sad few that made it didn't do much the whole season. My seeds were from Swallowtail Gardens. I'm moving onto the Trailing Sapphires instead. Perhaps the trailing ones are less finicky than the uprights?

Hi!! I've been gone for a while. I am getting in the mail a number of seeds my spouse ordered me for a birthday present. In one of them I got a "free" Lobelia erinus packet. I know doodly squat about these, but it seems that the 70-75F temp is needed, and it only gets that warm for a few hours on sunny days. I do have a unconventional set up that consists of a converted aquarium with some really ghetto tin foil on the sides and a spot light on the side-an actual stage spot light. This will get me the heat I need, but I'm curious if light germinating seeds will fall for this artificial sun. I think it's full spec-even though it's not any kind of "grow light" or fluorescent. What do you guys think? Also, do these little guys do better in a "seed starter" soil or best to use something with more nutrients? Thanks!

I think your set up will work fine. I didn't use any heat this year and the seeds came up within 5 days, with seeds from last year. Just put some cling wrap over the pots to keep the moisture in until you see the first tiny green leaves, then take the plastic off ASAP.

As for the light, it just means that don't keep them in the dark; it doesn't need strong lights to germinate, just some. Light duration is more important than the actually strength. I've grown these every year, and my first year didn't even have a light set up, just placed them on south facing windows during the day. They did great!

The biggest challenge with lobelia is separating them and transplanting them into pots - they are tiny!!!

Last year I sowed them in clam shell boxes - a pack of seed per box. Then when they were about an inch tall, I used a little scoop and scooped out about 1/2 teaspoon full at a time (10-12 plants?) and moved them to little 3oz cups were they grew until I planted them out, or moved them into baskets. Some people separate them into smaller clumps than that, but mine did just fine, they don't seem to mind being crowded together.