Hi Kelp!
All of the bulbs in the store only go up to 20 watts. I want to get 40-50 watts. Can you direct me where I can find a 30" bulb with a 50 watt output?
Sorry kelp, it doesnt work like that! If you are talking about fluoro tubes you are pretty much restricted to that wattage (i.e one size of tube only comes in one wattage). Compact fluoros are different, but you need a different fitting and ballast for them. So if you want more light your only real option is to retrofit some more lights over the tank somehow. To get the most light in the least amount of space I think compacts are probably the best option.
In answer to your original question, its more about how much money you have and how much time you have! If you have a fat wallet, you can plant your whole tank in one go! But of course, its much more economical to take cuttings and bunch the plants out as you take more cuttings. Then it depends on your light and speed of growth. If they are growing slowly its gonna take quite a while to get the effect you want.
As for bunching or planting single stems, it depends on the kind of plant. Egeria generally looks better if you plant it bunched, as it tends to just shoot for the surface in one line. For plants like caboma/ambulia that bush out really nicely, you can get quite a nice effect by planting the stems singly.
Sorry for the long reply! But I guess in the end there is no real answer - thats what aquascaping is about, trying to think about the end result you want, and figuring out how the different species grow and buying and planting accordingly.
If you want the basics,
http
/www.rexgrigg.com/ is a great place to start.
Hope this helps,
Nero