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when to graft onto seedlings in the field?

Posted by cousinfloyd NC 7 (My Page) on
Wed, Apr 4, 12 at 10:32

As much as when to graft, I'd really like to understand the why. When is it too early and why? At what stage of growth is it too late and why? I'd particularly like to know about grafting onto seedlings already established in the field. I suppose the answer varies according to species and grafting method. Should I also be looking at the forecast for the coming week when I graft, and if so, what should I be looking for? Are there other factors that determine the best timing? The only grafting method I've ever had any success with (mainly because it's about all I've tried) is whip and tongue, so I'd particularly like to know when to ideally W&T graft persimmons, mulberries, pears, and pawpaws. (It sounds like bark grafting might be preferable with persimmons, but I've had some success with W&T in the past, and I've never bark grafted before, so I figure I might personally have more success with what I have more experience with.) And what happens when trees are grafted in the dormant season? Does any graft union start to heal before buds start to swell in the spring or is everything truly dormant? Is the scion just sitting there waiting until that point? My assumption, which is probably a foolish beginner's assumption, is that I want to see very active spring development on the stock before I graft so that my scion will immediately receive lots of active nourishment from the stock. Is it actually better not to wait that long?


Follow-Up Postings:

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RE: when to graft onto seedlings in the field?

I've got some of the very same questions cousinfloyd! Hopefully someone will have some answers...


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RE: when to graft onto seedlings in the field?

I'm only a novice at grafting, but here is what I have learned thus far. Last year I was so excited that I grafted onto my apple trees in late February / early March. Way too early here in Wisconsin. Two out of three of my scions died, while one of them did take but most of the buds on it died. No doubt there was a cold snap or two, and/or the scions dried out before the sap started running. This year, I have used growing degree-days (GDD) to figure out when to graft. Based on Wikipedia, apple trees typically bloom after at least 80 GDD Fahrenheit, base 50 F (or 50 GDD Celsius, base 10 C). You can look up the GDDs for other plants besides apples at http://en.wikipedia.org/wiki/Growing-degree_day.

Based on this data, I actually wanted to take advantage of some of the growth that occurs prior to bloom at 80 GDD. So I'm experimenting by having waited until half that, or 40 GDD Fahrenheit, before grafting. We just hit 40 GDD here in my town in the past few days. I've got about half my scions grafted so far in the past three days. The buds are swelling with green tips on all of my trees right now, so I think this is far better timing than like I did last year where I grafted while the trees were still dormant.

Also, I have heard it said from a very experienced orchardist that the best time to graft is when you see the first dandelions. Well, just three days ago I spotted several dozen dandelions in a small patch about two blocks away from my house, so now I feel more confident than ever that this is the right timing in my area.

I might logically conclude that it is likely safe for anyone to graft after approximately 40-50 GDD. This applies mostly to apple trees but I would guess it could probably apply to most any tree.

You can find out the current GDD in your area at http://www.weather.com/outdoors/agriculture/growing-degree-days. Simply input your zip code, base temperature 50 F, start date January 1, end date today (or whenever), and it will spit out the GDD.

Of course, I won't know my success rate for a couple months yet, but I think my theories as substantiated by an experienced orchardist should be fairly close to the mark. If you don't trust my theories, you could wait until 60 or 80 GDD, as by then the sap is most certainly flowing and you should have no trouble at all getting your grafts to take, as leafing and bloom will be in progress by that point for most types of trees.


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RE: when to graft onto seedlings in the field?2

By the way... for what it's worth, I'm using the saddle graft method, which is very similar to whip & tongue except it involves cutting each side into a V shape. This worked for my one surviving scion last year so I'm willing to give it another go this year.

Also with respect to timing, I think if you're uncertain, it's better to wait too long than not long enough. You want there to be some sap flowing. I wouldn't wait as long as July because by then growth is slowed and it's getting hot outside. But I would imagine anytime in April or May or even early June should be just great. In theory. :)


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RE: when to graft onto seedlings in the field?

The tree needs to be well out of dormancy- around here we say that you should wait until the leaves are the size of squirrel's ears, and that is typically towards the end of April. I continue spring grafting for about three weeks, by which time the scions may be breaking dormancy anyway.

Grafting later will work if the scions are still dormant, but the scions won't have as long to get established before winter sets in and it leaves them more vulnerable.

"Summer" grafting is budding or chip budding and is done with dormant buds from the same year's growth. So the buds have to be mature enough, and that means July or August. Those buds won't emerge until the following spring.


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RE: when to graft onto seedlings in the field?

I usually start grafting when the rootstocks start breaking bud - though I did some W&T grafts of pecan and hickory in early-mid March this year - and some of them are now unfurling buds, so it looks like that may be a reasonable undertaking in the future; invariably I have a hard time squeezing in grafting time in Apr/May, as my 'boss' has other plans for me(knowhutimean?) - if I can graft before I have to start mowing/weedeating, etc., I'm way better off.
But, to do bark grafts - which is what I do for MOST things - you have to have 'slipping' bark, and that's not gonna happen until the rootstock is no longer dormant.

First persimmons I ever grafted, I just did a simple splice graft - no one had told me that persimmons were hard to graft(they're not) at the time - and I got 100% takes. I'm of the opinion that just about any technique you can use on apples/pears will also work with persimmons.

Seems like I saw somewhere recently that callusing of the graft actually commences from the scion side of the union - maybe has something to do with auxins from the buds, in a more apical location, initiating callus formation?


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RE: when to graft onto seedlings in the field?

Here in the south there is also "summer budding" where dormant stored (refrigerated) buds are budded into actively growing rootstock, probably more in spring than actual summer. A few weeks later the rootstock is half snapped off a few inches above the bud to force it and after a few inches of new growth from the bud the upper rootstock is cut off. I will try this with some pears in a week or two.


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RE: when to graft onto seedlings in the field?

I am hoping my grafts take. I grafted pears two weeks ago and apples last weekend. The apple tree has yet too bud so I think I probably should have waited another week.


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RE: when to graft onto seedlings in the field?

One year I did many apple/pear grafts when the buds were barely beyond silver tip and I had a relatively low rate of success - more like 75% instead of the usual near-100%. So I would say 1/2" green or later. Don't go too late on apples though, the earlier they take the more growth you get in the first season; later grafts miss the spring flush. Stone fruits don't have the big spring flush like apples, so getting them done early is not so critical. Outside temps are more critical for stone fruits however, peaches in particular -- they like 70F and the further from that the less happy they are. I should have grafted more of them last weekend, it was forecast 60s but has been about perfect temps for the last several days. Cold is coming here tonight so the next good window looks like the weekend or later. I graft a bit in each window that comes along, to spread out the odds. I did do one graft this weekend, I put 7 apricots on one trunk. I have high hopes on that one given the good weather right after I did it so even if the later grafts are not so lucky I should have the varieties. For apples I often do only one grafting of each variety. This year I did two grafts on some of them at different times since I had some extra limbs I didn't want to keep long-term but could stick a variety on for a year or two without a problem, in case the main graft did not make it.

Scott


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