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Sounds like to me that you are refering to inches and not feet! Plants can easly be 1-2 feet wide and however tall you grow them. My advice is to use Rockwool cubes (4 inch cubes) veg your plants until the fifth level (Y), then put to bud.
Depending on how many plants you wish to grow will determine the space needed for your vegetation area. Your cloning and vegetation area can be one of the same if space is available, since they both are on a 24 or 18 hour lighting cycle. By using some simple math we can determine the space needed. Let's say you want to grow nine plants. We can figure each plant will need two square feet per plant. So, 9 (plants) x 2 (square feet) = 18 square feet of needed space to grow nine plants. Although less space can be used, your plants may not get enough lighting per plant that is needed for good strong healthy stocks and good vegetation. In other words your plants would only grow fast and tall making them weak, not good for budding because stems begin to break from the weight of the buds.
This is my rule of thumb, not everyone may agree! Also you'll have one huge heat problem with the lights your using, if used in a small space.
Grow like below and you should be ok! But heat will still be a huge issue. Veg only to second or third level then set to bud like my pic below.
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