I live in an area where there used to be a lot of industrial hemp grown back in the day, and you still see a lot of it growing wild around here. My problem is, every time I grow outdoors, everything ends up getting cross pollinated towards the end. First really good stuff I grew a few years back was a Blueberry strain, and I thought it got stressed by heat that year and went hermi. Last year I had some White Rhino that looked to be killer, but towards the end, both turned a different color of purple. Pics I’ve seen of White Rhino don’t show any purple in the plants. Also, again towards end, everything seeded out. I had 4 different strains and some of them had more seeds than others. I have a high tolerance, so only one of them really had any effect on me, and I had to smoke a couple bowls. On the other hand, few people I’ve shared with said was pretty good. I’m thinking they would have been so much better if they hadn’t had to devote energy to seeding. I’ve read that cross-pollenation can occur up to 5 miles. Am I going to have to stop growing outside?
I was just reading an article about wild weed…The solution would be to grow autoflowers and time the maturity to NOT COINCIDE with natures hemp pollen production.
Pollen does not only come at the END of the grow cycle so if you are not seeing CROSS POLLINATION until the end…it is something else. When photo plants go to flower, within a couple weeks, the buds will begin to seed…not just at the LATE flowering cycle.
Maybe bad seeds?
I have same problem they grow hemp here for cash crop substitute for tobacco and i had to stop growing outdoors sucks
You’ll probably have to grow indoors or green house with filtered intake. You could try and time it out around the “main” pollen release, but that’s iffy at best, and will be dependent on local geographic and weather factors.
Cross pollination can occur up to thirty miles, not including downwinds, per my inspector. He was a bit miffed I use reg seeds because apparently I fling the pollen out the windows when I’m not paying attention. I jest, but he educated me early on and doesn’t like my using reg seeds. He waits to come to my place last.
@kmac03 this is why I quarantine outside. I have a dome I made out of PVC and plastic tarp that I put over males I intend to keep to breed with. Keeps the pollen from escaping and then after harvest you can just reveg and take clones and keep the male clones in a separate dome and breeding area to control pollen.
It works pretty well.
@moore2175ee I’ve had this same issue before myself.
I ended up creating a closed inflatable greenhouse that worked pretty good based off of the design I’ve seen from those massive positive pressure inflatable greenhouses that use wind to inflate and push pests out.
I made a clear plastic dome with a zippered front access and a few small slits in the top for exhaust. I then dug a trench around the area I wanted to cover. I only did a 10x10 space. I then set my plastic sheeting down and put the edges inside of the trench then staked them down and filled the trench back in. After that I hooked up an intake fan with a carbon filter and hepa pre-filter to the intake hole I cut in the side. Turned the fan on and it inflated just how I intended. The positive pressure let’s some air escape the zipper and vent holes which keeps flying pests and pollen out. The only thing I would change to my design is maybe adding some pvc to the sides because when you enter it will collapse some if your intake fan isn’t powerful enough and those pipes would have kept the tent from falling on my plants a few times. Also make sure if you try it that you keep plants far enough away from the intake that they don’t get wind burned.
@moore2175ee I used a 12 inch 1000 cfm fan BTW. The full size of the space was 10x10x8 after inflated. I made it 10x10x10 but buried a good 2 feet in the trench.
Sounds like a fantastic idea for when I have outside space to do so. My face is plastered against the window every day with good thoughts. 
Thankfully, I’m not licking the window yet. 