I'm needing a shade annual for a new raised bed & I'd like to take these (begonias) on for next year........

With a greenhouse you may do better than I. I just grow under fluorescent lights, in my studio which is on the cold side in the winter.

I think my biggest mistake was that I used the same fine peat based starting mix that I usually use for everything else. From what I have read a coarse mix is much better for them.

I have been very successful growing them from cuttings. What I should do is go buy a few plants right now, keep them in pots, and plan on cuttings over the winter.

There is a Begonia forum here, but it doesnt seem to active.

Here is a link that I found helpful.

If you can find pelleted seeds, it will make the job much easier. Begonia seeds are eensy weensy. I also strongly recommend a two step method : 1) seed germination in a regular, bagged potting medium using bottom heat. 2) transplanting the tiny seedlings into individual containers for growing on.....no bottom heat and using a very porous medium. I use cell pack inserts and plastic flats. (18s and 32s)

Don't forget that begonias need light in order to germinate. That means you'll need to spray your seeds into the mix with a fogging nozzle or plant mister.

Do NOT use those awful peat pellets.

A regular potting mix such as Jiffy or Pro Mix is fine for germinating. Those super-fine germination medis are too fine

Keep the bottom heat on until all seeds are up, then unplug it. That's one very good reason to germinate the seeds in one flat. You can sow hundreds of seeds (depending on the variety) in one flat! That's pretty easy to heat. For my personal needs, I would use two or three seedling flats, which I would transplant into cell packs as soon as the seedlings can be handled. Two or three germination flats translate into several hundred plants, easily handled in their reusable plastic inserts and flats.

Once transplanted into the coarser mix, the plants grow like gangbusters. Be prepared to begin a fertilization routine.

Thanks folks! rhizo_1, would Fafards 3B be suitable for growing on media when transplanting to cell packs?

Also ..... If sowing a pelleted seed, can they be sown by hand?

The pelleted seed can be individually handled with your fingers.

One hint that I think is important is to keep the soil warm through the germination period, but the surrounding air temperature needs to be cool. Heating cables or heat mats have been essential to the success of my seed germination and growing experiences over the years.

Good luck! I know that you'll do just fine. Your begonias will be lovely.

I am interested in learning to sow using the plant mister or a fogging nozzle (had to Google that one) that you'd mentioned earlier..........