well the problem there is that to keep them around a foot tall, you would need to flower them while they were about 4 or 5 inches tall. But since cannabis grows so fast, at that height it will be quite young. The plant need a bit of time to mature before set into flowering, the common consensus i've found is around 60 days depending on strain. (strains not being my strong suit) What i do suggest is once you get sum healthy females going and take some 4 inch clones from them. To ensure females by the way you can take clones while they are in veg, wait for them to root then flower them to determine sex, so by then you will know the sex of all your plants, not to mention, the females you do have in veg will be ready to be cut for clones, and you will already have hopefully a few rooted femmes. So, working with 4 inch clones, once they have a sufficient root system you can flower them. While this may sound like a lengthy task, it will give your plants plenty of time to mature.... and growing herb takes time.... but truly makes the phrase 'good things happen to those who wait' ring very true

good luck man hope i helped