Tree Settling

Hello Everyone,

This will be my first post with a quick ask for advice on the settling of trees after planting. I'm glad to have found such a community of knowledge. We are going into our second growing year at a new location. Last year we planted using an auger into silty loam soil and did not anticipate the degree of settling that has occured. In a number of cases, the trees are sitting 6 to 8 inches below the surrounding soil surface. In future we will dig holes that are much shallower and anticipate the settling, but I'd like to hear some thoughts about steps to address our current situation. About 50 of our trees are in this situation. We grafted a number of different caliper scions and rootstocks, so the graft point heights are quite variable. For those where the graft is sitting below the surrounding soil, I see no alternative but to dig the trees and move them up. For those with a graft still above the surrounding soil however, I would like some thoughts on whether we could slowly add soil over a year or two to the holes to bring up the soil level. I am concerned about rot in the bark on the trunk and smothering shallow roots if we proceed, but maybe this is not an issue with such young trees if done slowly? Do young trees have the ability to adapt to the changing soil heights if we proceed? The rootstock is Bud 9 if that helps.

Thank you for any helpful insights you may have.

Geof

Zone 5a
Ontario, Canada



Edited 1 time(s). Last edit at 03/23/2016 08:32AM by Geof Hall.

Geof, give an indication of what you did with backfill and how you treated the area afterwards, as this helps.

Any organic matter in the backfill will wind up being reduced in volume through microbial action. Also, a certain amount of leaching of finer particles and compacting of fluffed soil will always take place. This last point is why many will use watering and stamping to firm the area, allowing for good root contact and lessen settling. Mechanical digging, unless in very sandy soil, almost always leads to depressing depression. A clay soil in particular, but even hand digging in the heavier soils means a very firm outlying area, and a fluffy bowl of backfill, which by the laws of physics, has to settle.

If the depression is filled gradually, the tree will adapt. Aerial portions can behave like root systems, and vice versa, as a plant adaptation. For instance, more cold tolerance is capable of an exposed root if the part is exposed for most of the growing season, taking on the hardiness of a trunk section. The inverse is also true. Quick burying of large length can be fatal, or in heavy soils, lead to disease. A lighter backfill is going to cause fewer problems.

The fact that it is bud 9 of course means you are likely to get scion rooting. It would take years to overpower it, but it would happen. This is trouble in high density systems. For those out there that are using dwarf stock to speed up fruiting, this method can be used to turn a precocious tree into a towering, long living and high yielding giant.

Walden Heights Nursery & Orchard
Zone 3 in Vermont

Hi Todd,

As we backfilled, we tamped it down by hand and foot, but in the end, we went a little too deep with the auger, leading to a deep hole of light soil below the rootstock. All holes were watered, but the settling happened on a number of them over a period of weeks. It was a lesson learned on our new soil that we can adjust for next time with much shallower holes and anticipation of the settling. We have used Bud 9 for a number of years, hand dug in a much sandier soil without issue.

Thank you for your response. We have never had to consider resetting trees under this scenario and appreciate the discussion. I think slow filling of the holes where the graft point is still above the surface level is in order. We are not high desnity, but would like to maintain the dwarfing effect of the Bud9.

Geof

Hello everyone - first post here although I've been reading and re-reading this and other similar forums as well as michael's two very helpful books for several years. Thanks to everyone for sharing your experience.

I have the inverse problem. I planted a small orchard of ~30 heirloom desert and cider apples this past spring (April 2016). Hudson River valley zone 5b. Very well drained gravelly loam. B118 and mm111 rootstock at 18x25' spacing. Site had been in hay production for decades. I had wanted to do a thorough multi-year preparation to the field per michael's protocol but life got in the way. So instead, in the late summer of 2015 I double dug and amended a 10 sq ft area at each tree station and covered with hay.

Anyway, on tree planting day, I had my early 20s niece and nephew and a few of their friends help with the planting. I set them to re-digging the holes as I went to get other things ready. I came back and found one of the young men, who was more on the brawn end of the spectrum, up to about his waist in his hole. Looking around the orchard I found multiple occurrences of too-deeply dug stations (I swear to heaven I gave clear instructions!).

This thread flashed into my mind, and when planting the trees I deliberately set them shallow. I was shooting for the graft union at 3-5 inches above surface, and some inadvertently got set higher. Fast forward 6 months, and the unions haven't settled much and are still high.

While it may be a moot point and damage may be done, I've read a bunch of extension literature to anticipate the consequences and learn for next year. Advice seems to vary widely - penn state says a 1-2 inch height is "critical" to mm111 planting while Michigan state says in general to plant a minimum of six inches above surface to compensate for multi-year soil settling.

Any problems I should anticipate? Thx in advance!

Hudson River Valley
Zone 5B

Hello - given this didn't garner any replies, I figured either (I) it was a bad question; or (ii) everyone was busy with the harvest. So I figured I'd give it another shot now that we're in the dead of winter. If it was the former, apologies in advance for cluttering the site.

How high out of the ground are the graft unions? You say you were shooting for 3-5", what did they end up being?

Mike Biltonen, Know Your Roots
Zone 5b in New York

Probably 6" on average.

Welcome to Geof and Welcome Jon,

This reply is geared towards Jon's request for feedback

Hi Jon,

You have several options, I feel.

1) You could do nothing, assuming you are not also seeing a number of feeder roots exposed on the surface (or above it), the trees on B118 and MM111 should adapt just fine
2) You could add soil to each tree to mound them up 2-3 inches each
3) You could add 3-4 inches of pea gravel mulch to each tree as it will benefit your plantings on several fronts

The drama of the higher (too high) planting will diminish over time as your trees grow and will ultimately be negligible.

On MM111, I have had noted problems with excessive burr knotting on varieties that were planted higher out of the ground then others. This has not been an across the board problem though. It definitely varied by cultivar. This may be in part why Penn State wants the grant to be just barely above the soil line for MM111.

As you said, "6 inches on average" that means to me that some are still 8 or 9 inches above grade? That is too much in my opinion. I would add soil to those trees and gently taper it to the native soil line in a ~4ft diameter circle around the trees. Mulch as needed to protect that area and keep the soil there (lest it potentially erode away)

If it were me, I would do a combination of #2 and #3 above. Depending on my soil testing results, I would also take advantage of the opportunity to then use the native soil and blend in some key amendments (rock dusts, any meals, humates, etc.) and top dress those trees as desired, as the young trees will be feeding in that area in the next few seasons anyway, then pea gravel mulch a 3-4ft ring around each tree and ramial wood mulch the area just beyond that. 30 trees and this kind of work plan is very doable over a day or two.

The soil settling aspect varies from site to site, soil type, slope, how holes were prepared, management practices, and more will all play into the net results. You have had most of a full season in the ground with these trees . . . What kind of settling did you see occur in your planting?

Jon and Geof, post up some photos too, those are always nice to see along with the story at hand.

Gopher Hill Apples
Zone 8 in California

This is really great feedback. Thanks for taking the time to post it. I'm going to measure each graft and use a combination of methods above this spring depending upon the severity if the problem.