I've grown seed geraniums for a number of years and they do as well if not better than the cuttings I used to use.
I also use a small 5' x 5' greenhouse in the basement to start them off, but that's more to keep the cat out of the pots, than for environmental control. In fact, I keep three sides open after they start growing otherwise it gets too hot inside from the lamps.
It sounds like your problem is not enough light. I keep two sets of double fluorescent lamps (total 4 tubes) about 2" to 3" above each shelf of seedlings. As they grow, I raise the lamps by shortening the chain loops they hang on. If you don't have enough light or if it is too high above the seedlings they will get long and spindly.
I grow my geraniums in a soil-less mixture of 50% peat moss and 50% vermiculite and water thouroughly when the top half of the mix gets dry... usually about every 4 to 5 days. I also add a half strength dose of 20-20-20 soluable fertilizer to the water each time I water. Then I spritz the base of the seedlings and the surface of the mix with No-Damp, which I pre mix in a small misting sprayer bottle. (I find that as effective and easier than adding the No-Damp to the regular water)
Some folks start Geraniums in mid January, but I find that they get too big by the time we can plant ours outside in mid to late May... so I don't start mine until the second week in February. They are blooming by May anyway.
I start them in small packets and transplant them to 5" nursary pots as soon as they are about 2" tall.
At the beginning of May I move my greenhouse outside on the patio and eliminate the fluorescent lights. If the temperature gets too low I can quickly move the plants inside for the night as they are in large plastic trays. In the daytime the greenhouse door has to be open most of the time so the plants don't bake in the sun. I also keep a white bed sheet on the inside of the greenhouse plastic to control the sun's heat on the south and west sides. By the time they get planted outside they are well hardened off.
I plant about 30 or more geraniums every year and have fantastic results.
Happy Gardening

One thing when starting plants inside is to water from the bottom. To tell you the truth, i can't remember the exact reason why - possibly to help prevent damp-off? I just remember that i was advised to do it, and i do. Seldom have trouble with damping off.

I read on a hosta forum that you can stop the mold from forming on the soil by adding a few drops dish detergent to the water. Do this each time you water or fertilize. I haven't tried this yet so cannot say for sure that it works. What kind of seedlings are you going to grow? You should check out the winter sowing forum here. Another good one with lots of advice is www.wintersowing.org. Marg

You start with soil-less mix. I use Sunshine mix or Promix.
The mix should me moist but not soaking...I use warm water to wet the mix before sowing the seed. If you happen to get it to wet..add more dry mix to it...till it is damp but you can't squeeze excess water out of it.

So the seeds according to the directions on the package or in the catalogue or seed starting pamphlet that some seed companies send out when you order seed. You can also look this info up on some sites that sell seeds. Some are surface sowed and will need light, others prefer to be lightly covered and dark.

After sowing the seed, do not let it dry out. I mist with a spray bottle or mister when needed. If I sow in pots, I put a baggie over the pot till I see the very first sprout, then take it off. If I sow in trays I use the plastic domes and take them off as soon as I see the first sprout. I examine the pots or trays twice a day to see if there are any sprouts. Once there is one sprout, the rest will follow....even without the dome or baggie. It is more important to have air movement around them at this time.

Some even use a fan blowing over their seedlings to make sure the air is moving and to prevent damp-off and mould. Again it is very important to make sure the seedlings don't dry out. Lots of air movement and they will dry out fast.

Watering from the bottom is a good idea and will help prevent some problems. I however don't do that...I have way to many seedlings to even attempt that. But I use a watering can with a very small spout until the plants are big enough to not get bowled over by the flow.

To prevent legginess.....make sure the seedlings get enough light. This means 12 to 16 hours a day after sprouting. If you want to start seeds with window light...make sure to chose plants that can be pinched back. By doing this the plants will get bushier instead of tall and leggy.

I would recommend starting with just a tray or two, with some easy starters. Something like marigolds and petunias. And don't start them to early....again start according to the directions for home sowers....not commercial growers. This will mean when you plant them out...the seedlings will be smaller that if you buy them...this is okay....they will grow.

Geraniums are not the easiest plants to sow and grow. They take lots of light indoors...and will usually lose a few leaves until you get them outdoors. Zonal geraniums are usually cheap at the grocery store or in box stores....worth it to pick them up around planting time.

Hope this helps.

Sierra

I grow Geraniums from seed every year as well as cuttings. I have the way I do cuttings in my clippings. The biggest secret to being successful is letting the cuttings callus over before planting. Geraniums are easy to grow from seed as long as you don't over water and they get enough light and heat. I have a $30 grow heating mat that I put under my flat. Damping off or any mold needs wet and cold to form. A cold garage is not a good place to grow seeds unless you can provide heat and light.

I start my seeds on my south facing windowsill at the end of February and grow them inside until I move them into my greenhouse in mid April. I do them much like sierra does except I add some damp off to my water, both in the soil and my mister. I use saved mushroom plastic containers which I've poked holes in the bottom for drainage. 2 of these will fit in one of the clear plastic containers you buy croisants in and it has a lid you can snap down or hold with a clothespin. I transplant them into the 4 packs you buy plants in when they start getting crowded and then into pots in the greenhouse.

Watering from the bottom has nothing to do with damping off. Watering from the bottom makes sure the soil is wet right through. It keeps the seeds as you sow them and does not wash them into little valleys in your soil so you have a clump of seedlings and half the flat empty. However I stick to misting and just giving a little water occasionally before they sprout and when they are small.

Thanks everyone for the good advice.

I think I may need to install a door on a room downstairs to keep the kitty cat out. Warmth and lots of light aren't a problem, but the cat is =:)