How should I work my plants in order to get a harvest every three weeks? I was thinking....I smoke an ounce a week give or take a couple of days but at least a week. One auto flower plant usaully yields around 2 ounces....how many plants should I keep going to where I never run out?
Hoss has it right.
If you want to harvest a plant every three weeks, you'll need to plant one every three weeks. Pretty simple, no?
If you need an ounce a week, and want to harvest every three weeks, your harvests will need to be three ounces each. At 2 ounces per plant you'd need 1.5 plants per harvest.
Alternatively, if you were to harvest every TWO weeks, your harvests will only have to be 2 ounces each, and that will fit your description of 2 ounce autos better.
As to how many plants you'll need, that depends on how fast they go from seed to harvest.
For example, assuming you are growing two ounce plants, and harvesting every two weeks, and that your plants take ten weeks to go from seed to harvest, then you'll need five plants going at all times. Every time you harvest one, you have to start a new one.
Note that unless you want to start from feminized seeds all the time, you'll have to start extra seeds each time to cull out the males. So that might add a few seedlings.
Alternatively, if you started from CLONES, depending on strain, you might go from clone to harvest in as little as 7 weeks.
That would cut down on the number of mature plants you'd be harvesting a bit, but you'd still have to maintain a mother plant and take/maintain clones.