actually, I have a spare set...and 'Trewithen Orange' isn't going to last long here on its own roots. So if I can find some that match well for size and whippiness, I will try another one where I carefully score the stem with an x-acto knife or industrial razor blade.

btw pt 2. the band pots are both glued together w/E6000 and taped with duct tape...so hopefully that won't be an issue LOL. One nice thing about the square ones, it's a lot easier to do this than the round ones.

Well, it can't be any worse than grafting a scion into an etiolated new shoot, grin.

Go for it and let us know how it goes?

It is possible there will be dead bark trapped in the union and it will be a poorer union than if you scratched the bark away with your nail first. You could unwrap it and scrape the bark with your thumb nail and then wrap it up again.

This is a suggestion based on other species, as I know nothing about Rhododendrons.

Yeah, after I slept on it, I figured I should at least scrape one side/set of edges. Wrapping it up is such a hassle though, if you aren't a pro...but I guess I'm getting better at it.

You just don't want to go more than 1/3 in, David, regardless of caliper.

I cut my scion on one side only and then cut a wedge on the scion that will face into the cut on the rootstock. So that means I make my long cut on the scion and then flip it over 180-degrees and make a wedge. Then I make the same length cutting on my rootstock and turn the knife in towards the pith to make a wedge in it. The flap on the roostock I cut off so there is enough to only cover the wedge on the scion. I've found that less cuts yield better takes.

I grafted persimmons this spring that are 1/8" caliper. The only grafting option I had too was an approach graft. A thicker scion/rootstock a whip and tongue graft is much more preferred over approach grafts.

Dax

Thanks for the advice Dax and Jocelyn.

Well I reworked the one, and did the other 'Trewithen Orange' I had. That one was so thin I was worried a full wrapping of elastic would crush it, so I used parafilm and just a single knot with elastic. On that one the scion was still green so maybe it will heal even faster...OTOH maybe the wounding will cause more problems. I tried to make the smallest slice that seemed like it would expose some cambium on either side. It's nice working with 'Trewithen Orange' because of the amazing cologne-like odor of the foliage.

I guess I'll know by the end of the season. I assume if I remove the wrappings and a callus has formed, it's ok to give the plants one more winter on their own roots? Then make the final cut next spring? Of course they will spend a few more winters in my garage: Hardiness-wise, 'Trewithen Orange' is always going to be a very close call around here. But at least I can have a plant in a big pot to breed with.

Hi David,

There's no rush to remove the tape. Leave it on until you know one way or the other that the graft is a success.

If the scion grows next year then have a peak to see the callous. If in your mind the bond of the scion to rootstock could easily snap in high winds, recover the working area until it's beefed up enough to completely remove any tape/rubber bands etc-

You can also put a stake right up against the plant and tie to it for extra strength.

Dax

Thanks again for the advice Dax. We'll see what happens. Horticulture is definitely not for the impatient! (nor is dealing with the American nursery industry, but I digress...) Hopefully between two of them, one will take.

Yes & keep the media on the dry side for the next three weeks, David. Then put them up against the north side of structure for a week. If they're already up against the north side of a structure that's fine. After that you can water them normally.

Dax

Well, I'm on a roll now. I better learn how to do this, even though after so many graft failures in the past I don't want to waste any more time. But maybe approach grafting will prove better suited to these plants and the types of matches I'm trying to make, and the limits I have climate-wise and equipment-wise. (Perhaps the European nurseries who do a lot of simultaneous rooting/grafting of rhodies have misted greenhouses...not something I would be willing to invest in.) And as Jocelyn says, the only way to learn is to practice.
So this is my latest, probably even more hare-brained than the last because I'm trying to get the very thick stemmed R. rex to attach to 'English Roseum'. I tried Dax's "tongue and groove" approach. Now let's talk further wrapping of this w/parafilm. My angle on the matter is, unlike a conifer in winter, these are actively growing. They will be transporting water up from the roots all summer anyhow. And I'm in a climate where it's pretty much impossible to have a low dewpoint in summer...there's just too much warm coastal water too nearby. So it's not like it will dry out if I keep it in a very shady, cool area. So am I ok to think I'll just skip the wrapping? Or is there no harm in doing it so I should do so anyhow? Can't mildew and fungi proliferate under there? Maybe just lightly wrap w/parafilm? Try not to make it completely airtight?

BTW I have been told a crazy rhododendron collector in NZ has successfully done grafting of these thick stemmed giants onto "normal" root stocks, for years. So the size difference will not be a long term problem, though it could be a problem at this stage. It's a bit baffling because rex et al. should all grow w/o trouble in cool summer NZ anyhow, but maybe it's being done there just because they grow better, period, on plants whose historical popularity in cultivation was because they were selected, among other reasons, for very strong root systems. I had some max X calophytum rooted specifically to act as root stock for grandia and falconera series big leafs, but I don't want to risk those plants until I know what I'm doing.

Anyhow thanks again for the tips, Jocelyn and Dax...I'll take the light wrapping approach unless there's some strong reason do something else.

Dax is the ideal behind keeping them a little dry that being too watered keeps the callus from forming?

David,

You'd be best to put up a small camping tent up against the north side of a structure and place your grafts inside. This will provide the constant humidity necessary for any type of graft to not dry out. I don't think you need parafilm tape if you have humidity for summer grafting. It wouldn't hurt but it's not necessary. Now rhododendrons are not something I've read up on. Grafting is grafting to me though and those tips are what I would do for anything I'm grafting this time of the year, or, especially at the end of July into August. The middle of August is optimum time to summer graft because that's when the roots are most active (at any given time of the year.) Less energy into producing shoots in spring while active rooting is occurring is the opposite of August. Some people graft in November also after plants have fully gone dormant and while roots are active, but, you'd need a pretty warm climate or greenhouse at that time.

The reason for less water in media is to decrease bleeding at the union. When plants are watered they want to grow. If you starve a plant of water they will slow down. During healing, when there is an active flow of sap, it will push the union apart, literally.

Recently I was on the phone with a friend asking for cuttings of Rhododendron to do later in the year and he told me that now is the optimum time. I replied that Dirr says otherwise and he said, 'Dirr doesn't know it all.' So, I'm going to assume you know more about Rhododendron propagation that I. As for grafting though, I honestly believe it's the wrong time of the year, but I cannot tell you if I'm incorrect.

Mid-August for two weeks, until Sept 1st is optimum summer grafting time.

I'll say one last thing. This is T-budding time and the window is closing. It's also June Greenwood Grafting. They're both basically the same. A bud is sliced out of a stick of wood for T-budding and inserted under the bark of another. In Greenwood grafting, rigid new growth is where the bud is cut out to be inserted under the bark. I honestly cannot compare these bud grafts with what you're doing; using a stick of wood vs. a bud. I do know however that a full scion is not grafted this time of the year on anything I know of.

Dax

" So, I'm going to assume you know more about Rhododendron propagation that I."

I wish I could say I did LOL! But funny you mention rooting at this time of year. PNW nurseries mostly root over winter. I've had no luck with it...bottom heat or not. (I have rooted hollies over winter which are much easier) But my tree trimming guys knocked a single branch off a highly coveted rhodie - I can forgive them one branch - and I figured, what the hay, I'll try summer rooting for the first time instead of throwing it away. That's in a large plastic bag on the north side of the house, so I figure per your instructions I'll put this one in a clear plastic bag on the north side of the house too. Maybe not seal the bag tightly though.

The thing about bleeding makes sense, but I'll have to be careful as these varieties don't like to be dry.

BTW it would be the wrong time to do standard grafting, but I think it *could* be ok for approach grafting. The couple of standard rhodie grafts I managed to do myself were in late September.

Sounds good. My buddy roots his in a nearing frame in pure sand that has a lid that comes down, so yes, it'd be the same as bagging on a north side, 100%.

The man that invented the nearing frame is Guy Nearing & he is from New Jersey, and, he was attempting to master rooting rhododendrons when he succeeded with his nearing frame. He used fine bark as his media.

Dax

Yeah, supposedly the Nearing frame helped revolutionize the ability to relatively cheaply mass produce rhododendrons. Albeit causing grafting to become a bit of a lost art in this country, at least. Would like to have met that guy...the old QBARS archive (Quarterly of the American Rhododendron Society) have various interesting articles about the plants he kept in New Jersey. Some of which I'm amazed he managed to keep alive. He must have had the true "green thumb" that we all aspire to have. Although now that I think about it, I'm left wondering if back then, before the mass movement of millions of wholesaler produced plants from many different parts of the country, what I'm always calling the "cosmopolitan" species of Phytophthora were in fact, less so. Meaning he was able to keep something like the alpine R. xanthocodon (a relative of 'Trewithen Orange') alive on well-draining New Jersey sand because whatever would kill it these days wasn't around. Back then a lot of the east-west movement of rare species for example, was only by pollen or seed, not rooted cuttings or whole plants. Oh well, who knows.

Interesting thoughts you have there.

Trewithen Orange - what a lovely rhododendron.

Dax