Of course you didn't have stuff like White Widow or whatever in the 70s but getting better and stronger weed only requires you to grow enough plants and get eno

Of course you didn't have stuff like White Widow or whatever in the 70s but getting better and stronger weed only requires you to grow enough plants and get enough variety that you can start noticing characteristics and then interbreeding and crossing strains to isolate them so your offspring express them reliably. You do not need high tech lab equipment to see which variety grows faster and produces more branching or bud sites or thicker buds or more thc glands etc. If you just sow a field full of random seeds and just forget about them until harvest instead of maintaining them, removing the males, etc your quality will be worse.