Tall plants are not a waste of time, effort, or money. Mine are routinely 4-5 feet tall and not stretched at all. I just don't "force" them to flower after a mere 4-6 weeks. The advice above, about moving the light is bad, unless you're looking for a lanky, stretched plant. If you want tall, yet full plants, simply let the plant grow naturally, do not force it to flower before it is mature enough to do so on it's own. Keep the lights close, but as the plant grows, gradually elevate the lights to accomodate the growth. Your plants will still grow tall, without stretching, and if you have adequate lighting from above and on the sides, they will fill out without stretching towards the light. Most people who force flowering before the plant is actually mature do it because they're growing in mommy's house or they have height restrictions in their grow area. Keep the plants well fed, well watered, and use decent soil or whatever you grow in, have enough space for proper root development in the container, and use good lighting at the right areas and your plants will grow tall, but not stretch, and be full and bushy also.