Yes, many junipers are dioecious. I'm not sure about the ones in question but it really doesn't matter because it is easy to tell the cones apart. Male cones are very small, yellowish in color and occur at the tips of the folliage. They look more like swelligs on the ends of the twigs. The female cones are larger (after pollination)about 0.5 in. in diameter and blue-green in color. If a female cone has developed up to full size you can be sure it has been pollinated.

Juniperus virginiana is invasive in many areas .... google your state and invasive plants to see if it is in your state ...

the fact that they naturalized a barren field, should be your first clue

good luck

ken

Never heard of anyone collecting male cones. Only the female cones will look like the bluish "berries" of cedar.
If you're going to plant them, you are aware that juniper seeds don't always germinate the first year.

Don't collect any of these you find.They are not cones and contain cedar apple rust fungi...not a "fun guy" to have around apples, etc.

Here is a link that might be useful: Cedar apple rust stem gall...scroll down

I found the shape of the female juniper cones also on the cones of Chamaecyparis nootkatensis pendula.

naturegirl, we have Cedar Apple Rust on a young 'rust resistant' crabapple, but I have never seen any of the galls as shown in your attachment on any of our junipers.

Thanks everyone for the good information. I guess scotjute summed it up. Basically if the cone is dark blue then it's a ripe female cone.

I wasn't sure if male cones looked like female cones but apparently not.

Yes growing juniper from seed is going to be a LONG process, since they may take a few months or few years to germinate. I might try growing a few from cuttings but winter might not be the best time to take cuttings.

The neightbor has a nice Grey Owl (Juniperus virginiana 'Grey Owl' I think) juniper and he's given permission for me to take a few cuttings. I'll have to read up on this and see what's involved.

Thanks everyone

Should you ever get so much into it that you travel elsewhere to collect junipers, just to add that they don't all have dark blue cones, some have orange-red cones, like this Phoenician Juniper (from the Mediterranean; note also the small pollen cones, this species is monoecious):

Or this Mexican Weeping Juniper:

And here's Syrian Juniper, which has larger cones than any other juniper:

Resin

Thanks Resin! Those are great photos of the cones.

Just so I'm clear on this, if I want to grow a Juniperus virginiana 'Grey Owl' for example, then I need to do it via cuttings rather than cones, correct?

If you want a named cultivar, then yes, by cuttings or grafting. Cultivars don't come true from seed.

Resin

The picture of the bluish juniper cones let me remember that those are often added when making Sauerkraut, the tastier kind. I never realized that when eating Sauerkraut and coming across those blue juniper "berries", they actually were "cones".
Bernd