You can stuff quite a few plants in a small SoG, I dare say more than some commercial seed sellers use in their selections. The main advantage of more space is that it saves time. Obviously you have more chance of hunting down a pheno in a larger selection, in particular in F2 where the traits get segregated and you're looking for the best combination of all the traits (the short hazy frosty sweet high yielding pheno and not the long version of the same for example). For proper breeding (breeding one or more traits true) you need to figure out if the traits you want to breed true are homozygous or heterozygous, and how they inherit (co/partial/complete dominant, or recessive for example). That is also easier/faster with large plant counts.
For example, if you cross two (true heterozygous) F1s you get the typical ratio of 25% AA, 50%Aa, and 25% aa (which if AA and Aa express in the same phenotype, i.e. is dominant, means 75%-25%, or 3:1 (
see figure 1) If you cross AA x Aa you get the typical ratio 50% AA and 50% Aa. Point is, observing these ratios can give you an idea of whether the traits are homozygous or heterozygous. On 10 plants, the 50-50 ratio could theoretically lead to 100% of those 10 being AA. Or you could get 5 AA and 5 Aa and think you crossed heterozygous with homozygous, or worse, homozygous with homozygous and bred it true, while with 10 plants it's entirely possible you got the typical F1 ratio and just didn't pop any of the aa seeds.
Check out my comment on plant count in my backcrossing thread here:
http://rollitup.org/t/backcrossing-your-own-variety.840329/ The same thing I said regarding plant count in the 3rd post also applies to females. Even if you want to veg longer to see just how they veg, you can still trim half the plant before you transition, or go as far as leaving only the main bud on, to finish flowering and test taste and trich levels etc. It doesn't have to be pretty every single round. 25 cramped together works a lot better for determining ratios and selecting for certain traits than 9 beautiful 3-oz plants do. Running 25 plants from the same generation twice (and keeping clones of the best from the first run, and logging trait ratios) is obviously even better.
What it comes down to is that it depends a lot on what your goals are. If you want to convince others you're the real king of cannabis then closet breeding isn't the way to go, but that certainly does not mean you cannot breed for specific traits and enjoy the fun of breeding. Even if you end up breeding only a small amount of important traits true, by then you will know how they inherit and backcrossing those strains into for example a better yielder or shorter flowering strain is a lot easier.
And it takes so long it give plenty of time to post long posts...
Anyway, good luck and keep me posted or let me know if you start a thread.
Last run they smelled like carrots.
