Should you plant grafted trees with the soil above the union?

14 years ago

Hi,

Although this question focuses on fruit trees, it applies to all trees:

Should you plant grafted trees with the soil above the union?

I make certain that I planted my pawpaws, American & Asian persimmons (all 1 centimeter whips and small saplings) so that the top of the root systems begin at just bellow ground level; this means that there is a good 2" to 3" between the ground surface and the graft union.

1. I read conflicting advice: some say that the way I did things is best because it keeps the trunk from rotting (girdling).

However, others on the GW have suggested that you should cover the trunk to just above the union so that, in time, roots will emerge from the grafted scion's base so that if the tree dies back to the roots, the re-sprouted sucker will be that of the cultivar and not the initial rootstock. This makes a lot more sense to me - EXCEPT in cases where the rootstock is needed for its dwarfing properties (i.e. as with dwarfing rootstocks for cherries and apples). If this is true, then I would imagine that pawpaws are a fruit you would really want to do this for, since they often die back, plus when the pawpaw puts forth suckers a few feet away from the trunk, the resulting colony will be that of the cultivar and not of the wild rootstock.

By the way, I noticed that one of the American persimmon trees had a yellow line which was 2" above the root-system and 1" bellow the graft. Should I have planted the tree so that the soil-level is level with the yellow line?

*Also, with the Asian persimmon, there is an odd union common to all of the Asian persimmons that were grafted so that it is not straight, but instead, the point of the union is crooked then straight upward. If the idea is in fact to bury the union, should I bury the entire union - maybe it will be good since the D. virginiana rootstock will offer winter hardiness and having some of the root-system coming from the Asian persimmon will perhaps eliminate concern that the union may grow weaker in time?

2. When planting trees, I always keep the ring around the tree completely level and consistent with the surrounding ground level. Then I place the mulch 2" high around the trunk, while keeping the mulch just a bit away from the trunk to prevent rot. However, even in arboretums, I see that trees are planted a few inches above ground level (that the soil is higher) and THEN increasing the mound is 1" to 3" of mulch. What is the best practice? Except in situations where you have a low-spot in the yard and drainage is a significant concern, what would be the long-term advantage of having the soil which is 3 or so feet around the base of the tree a few inches higher the regular ground-level?

Thanks,

Steve

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Comments (6)

Dan _Staley (5b Sunset 2B AHS 7)
14 years ago
Should you plant grafted trees with the soil above the union?

No.

However, others on the GW have suggested that you should cover the trunk to just above the union so that, in time, roots will emerge from the grafted scion's base

Find a trusted text and stick with it. For example, one that shows why the italicized is wrong (any text will state this, actually, so pick one that appeals to you).

Just because it appears on this forum doesn't mean it is correct.

Dan
pineresin
14 years ago
Depends on the species involved. Some are far more tolerant of being 'buried' than others. In species where they will tolerate deeper planting with covering the graft, this can have the advantage of stopping sprouts of the rootstock from taking over; it can also allow the graft to put out its own roots above the graft, leading to a healthier plant with no risks of failure due to latent graft incompatibility. This is standard advice for e.g. tree peonies. But for species which don't tolerate burying, this can be a quick death sentence. So there is no hard and fast rule that applies to everything.

Resin
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One inch of cover is plenty for NJ and will not discourage own-rooting (if the plant wants to do it). Don't bully your plants. Own-root is not good for many roses, including probably a majority of hybrid teas. Roses will survive very deep planting, but the reduced oxygenation can incapacitate the rootstock roots and slow the plant's development somewhat. I've dug deep-planted roses that had no own-rooting, but all the feeder roots developed from the rootstock shank, while the fleshy rootstock roots had not grown at all. This was in a location with adequate drainage.
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What if it was potted improperly - or potted up and a few handfuls of soil thrown on top of the container - or the plant arrived bare-root? All are very common occurrences. Your question can't be answered because you left out an important piece of info. Where is the graft? Is it at the crown, top of standard, or intermediate on the standard. We have to assume you're inquiring because the union is very low on the stem, but if it is above the basal flare (where the rootage makes the transition from roots to trunk) it should be exposed. When planting, locate this basal flare, even if you have to remove soil from the top of the container, & plant so it is at or just above the actual soil surface. Al
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Most of my roses are grafted on Fortuniana for our South Florida soil. I pay a premium for that rootstock so I make sure to try to preserve that graft. Conversely, if I buy a rose on Dr. Huey I tend to bury the bud union in hopes that the rose sprouts roots on its own. I know that a Multiflora or Dr. Huey rootstock will not survive past three to five years in my soil, so I try to extend its life by getting it to root. This can backfire if the original rose has a root system that doesn't fair well in my soil, but that has been the minority in all the cases I've had. If you live in areas that get freezing temperatures, it is better to bury the graft in order to preserve it and have the rose you want sprout back to life in the spring. In your case, I doubt you need to bury the bud union. Your roses will probably do much better on the grafted rootstock.
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Dan _Staley (5b Sunset 2B AHS 7)
14 years ago
So there is no hard and fast rule that applies to everything.

This is technically a better answer than mine, and the exceptions are generally for few cases. In general, some spp. can tolerate burial, but you want a plant to flourish in its environment, not tolerate it. If one is planting the type of tree that may benefit from deeper planting, chances are it is a specialty tree and the instructions are explicit. For a typical tree at the nursery, it is a death sentence, as we see in our neighborhood all around us.

what would be the long-term advantage of having the soil which is 3 or so feet around the base of the tree a few inches higher the regular ground-level?

Planting proud keeps the collar out of trouble, esp with water. Planting this way is generally not necessary in sandy soils.

Dan
kman04
14 years ago
Magnolias are often planted with the soil line at or just above the graft line. People then add soil over a period of a couple of years until the graft union is completely buried. They do it this way to make sure they don't immediately suffocate the rootstock(allowing the rootstock to adjust to the higher and higher soil line until the top graft is well rooted itself) before enough of a root system has grown from the top graft to support the top growth. This is done by some people with some fruit trees as well.

Many people prefer their Magnolias on their own roots for various reasons. Many have found that in fact many Magnolias grow much better on their own roots than grafted. Some do it because they are zone pushing and if the Magnolia dies back to the ground and is on its own roots, when it grows back it will be the same Magnolia they bought and not the rootstock.

If done correctly, it can be done with many(most) grafted trees. Though, if you plant the tree with the graft union well buried in most cases you will kill the rootstock before the top graft can grow any or enough roots to support the top growth and you will end up killing the tree.
debstuart1
14 years ago
What about semi dwarf fruit trees...apple and pear...just bought them...one had the same yellow and red line described below...at this point I planted the first so that the soil is just where it was in the pot...is this the right thing to do???

thanks

Deborah
brandon7 TN_zone7
14 years ago
Deborah, generally fruit trees are planted "so that the top of the root systems begin at just bellow ground level" as Steve described above. If you bought a potted tree, it should have been planted this way in the pot, but that doesn't mean that it definitely was. I would check before planting.

Should you plant grafted trees with the soil above the union?

Comments (6)

Dan _Staley (5b Sunset 2B AHS 7)

pineresin

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Dan _Staley (5b Sunset 2B AHS 7)

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