I don't have a lot of experience, did it last year and again this year on apples. Last year I did 3 interstem grafts, meaning I used a full size rootstock with a scion from a semi-dwarf rootstock to which I grafted my selected tree varieties scion to. They all took. I also did a interstem graft and planted it without a scion on it. That also took The Full size rootstocks were M111, the semi-dwarf were M7.

This year not so good I ordered late, wanted full size but the only thing left were B118 from Cummins Nursery. I also got one M7. I got greedy. I figured if I could do two grafts on a rootstock I could put more than one variety of tree on a rootstock, which I did. I put 3 different sports of McIntosh on one tree, and I put a Wagener and a King David on another ( the M7). I also did a red flesh combo, a Redfield on a Niedzwetzkyana which went on a B118. The B118 has a red cambium layer as do the two apples I grafted to it. All the apple varieties above came from the free USDA program along with a Cox's Orange Pippin and Keepsake I mention below.

I also grafted the Cox's apple to the rootstock combo in the ground from last year and the Keepsake to a Black Oxford I grafted last year. The last two both took. I also grafted from my own tree Golden delicious scions to one of the B118's above and also to a very mature Yellow Transparent tree here on the property. The one on the B118 failed, the one on my tree took nicely.

But to answer your questions, the cambium layer is the green layer, or red as above. But I don't really worry about the cambium. I use a crescent wrench to find the spot I cut so the rootstock and the scion match in diameter. And I make the cuts. I don't know why your scraping unless your trying to get a nice level cut. You're supposed to make a clean cut the first time. But I have been known to scrape.

I bought a roll of grafting tape off eBay for a few bucks, but I'd guess you could use kitchen wrap or better shrink wrap if you already have it,- it's thicker. I use teflon tape for the tip, unless there's no cut there.

Are you grafting apples to apples or other matching fruit. You can't graft oranges to apples.

I'd suggest you Google Whip and Tongue Graft for videos or text articles. That graft is done in the spring. I like this one from Cornell.

I'd suggest you try taking trimmings from a tree in the winter and practice on cuttings that you can dispose of. I tried T budding last summer and can't get the hang of that. None took.

edit: for link problems

Awesome! Thank you so much. I was told the Cambium layer is the critical layer for growth. However, I keep hearing I'm supposed to strip the bark until the white layer shows up. So, I was confused.

I'm trying to air layer my blueberries + guava trees. I love both of them dearly. I have another guava variety that has a very nice rootstock and I'd love to graft a few varieties on them.

Thank you for your help!

The cambium layer is the important layer. The way I do it with the crescent wrench ensures that your matching cambium layers on both sides. If I had more experience and better eyesight I could match one sides cambium layer on both pieces.

By the way I had trouble with the triple graft because I had trouble matching sizes and having bare buds. You might want longer scions till you get more experience.

The cambium layer is the green layer just under the bark. I have no experience with blueberry or guava tree propagation. But I do chip budding and cleft grafting on apple trees. All grafting/budding techniques needs to have the cambium layer of your scion and the cambium layer on the rootstock match up well to insure good success. Using a sharp knife and getting nice smooth cuts will help too.

Air layering? I have not done that in years. I recall doing a v-cut on a plant and then covering this cut with with moist spagnum moss. Wrap the area with plastic well to keep the moss moist. It took many weeks for the plant to root out at this wounded area. Cut off from the mother plant after it forms enough new roots.

I use white plastic grafting tape for my budding/grafting. No wax when budding, but I do wax over the area when doing dormant grafts on apples.

No , Saran Wrap will not work, you need to get Parafilm. The reason it won't work is it would not stay tight enough to keep the graft from drying out, especially when exposed to the elements.
My best advice to new grafters is never leave your Parafilm in the sun it will melt and be unusable!

I find the inch wide easiest to use:

https://www.toyboxtech.com/1-inch-parafilm-grafting-tape-ships-to-california-all-other-states-includes-zen-gardens-practical-guide-to-grafting-airlayering-1-1-inch/

Carla in Sac

You don't say which fruits you are trying to graft. That may make a difference. Each variety/species likes its own best method of propagation, time of year, etc. For example most people seem to have good luck with a cleft graft in June for mangos. But with citrus, I tend to use a bud or chip graft.

For deciduous fruits like apple, pear, etc. they may prefer grafting during dormancy. Look them up individually and read up. Lots of great videos on YouTube as far as technique.

I'm grafting my guava tree. I have a few mexican style guava that has really good rootstock. I plan to add a few scions from my vietnamese asian style guava to the mexican rootstock.

Definitely not a pro when it comes to grafting, but Re your other question about grafting tape and plastic wrap:

If you do not have any grafting tape. I've found that electrical tape (usually comes in black, readily available + cheap) has worked well for me, it's somewhat stretchy, good stickiness, and can be taped pretty tightly.

Plastic wrap works pretty well when it comes to airlayering stuff.