Not sure if I have anything worthwhile to add to this but not too long ago, one of our long-time trusted members, posted an article about Air Layering using a plastic pop bottle and peat moss.

The search function for me has become worthless so I can't find that article, but I think that would be a more reliable method than rooting.

I've seen the little plastic? "enclosures" that you can fill w/soil media and seal around an appropriate stem. Supposedly then after a year or two roots will grow from the stem into the media, then that can be cut off and planted.

Wrapping the outside with aluminum foil, protects it from the sun.

Roughing up a short area of the branch (leave a portion connected) and using rooting hormones, seal it up tight.

Do more than one branch, you can always use the extras.😉

I might give that a go. Although looking out of the window at a tree festooned with bundles of plastic might not be too attractive. Foil won't be necessary in the shade under the canopy. 🤞

floral,

I'm no expert but other trees I've seen air layered, they cut the outer bark all the way around the limb and remove it, so what I said earlier about leaving a portion of the bark connected is a product of my aging memory. In fact, the bark may repair itself if not completely disconnected around the entire limb.

You don't need pop bottles either. Any flexible plastic wrap would work to keep the moss moist. You want it as airtight as possible.

Shade is good.

This may help: https://www.rhs.org.uk/propagation/air-layering-plants

;-)

Thanks everyone. The twigs are very thin, like wire. Girdling them would difficult.. I might just rough up the surface. We'll see.

Not silver birch, but I've found river birch easy to root with summer cuttings. Mid summer with some rooting hormone, I might have had them in plastic for a few weeks.

I might try summer too then.

Well, I've done six air layers on the weeping birch. They look like so many bats hanging off the tree. The twigs are so fine I could get the bark off with a finger nail. We'll see if anything comes of them. 🤞

Any luck? I need to propagate my betula pendula dalecarlica (can’t find one anywhere!). From internet search it seems useless to try to root one of these; have to do grafting it seems

No. All 48 of the ordinary cuttings died. Three of the air layers did nothing. Three are still there. I'll unwrap them in a couple of months. But I didn't take a lot of trouble over it. No hormones and no bottom heat.

Darn

Not trying to usurp floral's post, but in the birch-theme, thought this might interest. Planted this birch from OIKIOS ~20 yrs ago described as a Himalayan "hybrid" birch. Their grounds were open-pollinated, so I surmised they actually weren't sure of this tree's lineage. Search shows horizontal lenticels on the bark of the pure Betula jacquemontii, and mine doesn't show them, so some evidence of hybridization. It hasn't had any birch borer damage, so hoping it escapes their notice. The tree doesn't have the elegance of silver birch or even the native paper birch, both w/their drooping branches, but still a solid tree so far.

Some info on the straight Himalayan birch.

https://www.thespruce.com/himalayan-birch-plant-profile-4845264

Continuing the birch-theme, here's leaves of some nearby wild cherry birch saplings which occur near me lower down in the moister areas.

.

Pretty cool, ben

Betula utilis var. Jacquemontii ist widely used here in winter gardens together with things like winter flowering heathers, witch hazel and coloured stemmed Cornus. Often grown multistemmed.

If you can be bothered you can enhance the whiteness by removing loose bark and washing down the trunks.

Unfortunately, Himalayan/Jacquemontii birch is susceptible to bronze birch borer, and even though the link in beng's post above says "You can propagate Himalayan birch from a cutting taken in the late spring or early summer" it's likely just as difficult to root from cuttings as other white barked birch species. Himalayan birch is generally grafted by commercial nursery growers.

River birch, yellow birch, and sweet (cherry) birch aren't as difficult to grow from cuttings as the white barked species.

So far BBB has not reached us, thank goodness. 🤞🤞🤞🤞🤞

Bronze birch borer (Agrilus anxius) - Forest Research https://share.google/Qhd2EcEu0sGtdo98B