Your only chance for success is a raised bed, same where I live. The soil is 100% clay that can be made into bricks.
Amending the soil will create a "bathtub" to drown your trees.

Here is a link that might be useful: mrtexas

I have Red Soil in my native country in Greece, which is mostly clay to a little clay loam in spots. Although it is a clay soil, it appears that these red soils native to the mediteranean have good drainage. I grow pears on quince rootstock and they are doing amazing handling the drought and putting better growth on than I have ever seen on a soil rich in OM like the one I have in Canada. Olive trees really thrive there too.

A question regarding raised beds on clay...

Firstly I have the same issue here. What I have done is: -scrape organics from the planting site
-scarify the native soil with a shovel.
-put a couple inches of imported soil down as a planting base
-place potted plant on prepared spot
-then create a mound with imported soil about 1.5-2 yards across.
I then mulch the mound, spring and fall.

The question is... is this not basically a hydroponic-style system? Will the roots ever leave the mound??
The plan has always been to mulch heavily each year (leaves/grass clippings/manure and wood chips. But won't this keep the root system in the mound?
Will trees such as apples/pears EVER actually amount? If we decide to stop mulching (or fertilizing)- won't they basically stop producing/growing?

I love the mound idea, I just worry about the realistic future of my orchard!

This is where amendments come in. You can grow the trees in your imported soil but if you thoroughly mix compost and the imported soil with a certain amount of the native soil in a way that leads roots from nearly all imported soil and compost gradually into nearly all native soil you'll likely have a better anchored root system with access to more water.

I don't amend any holes (but feed and water regularly) and my suggestion in your situation is EMLA-7.

I don't think the others will be vigorous enough in your soil and M-26 is not resistent collar rot so it is not good for wet soils. The probelm with EMLA7 is that it isn't quite as productive and takes longer to come into production oversus M26 or the smaller selections.

The fact that it is more vigorous tends to counteract the poor soil conditions.

Just to make sure, you didn't do this test after a big rainy period did you? If not, it means your soil is extreme clay. I am in Maryland and I have plenty of clay in my soil but its nothing like that. Either do a raised bed or dig up a large area with a backhoe and mix in a truckload of organics/topsoil.

Your rootstock choices are good ones (never tried Supporter 4 though). Quince is good for pears but is hard to find; I have most of my pears on various OH rootstocks.

Scott

Lind,

I've had lots of trouble w/ trees drowning w/ our heavy rains, high water table, and poor drainage.

Some fruit trees are very tolerant of wet feet, others not. Also rootstock can make a big difference.

Since there are so many different rootstocks, I'll limit most of my comments to fruits on standard rootstock.

Pears are one of the most water tolerant. Plums also rank right up there w/ pears.

Apples are a step down, but still fairly water tolerant once established.

I've found tart cherries are water tolerant on Mazzard (not Mahaleb).

Peaches and apricots won't stand for soggy soil. I continue to see peach skeletons in my neighborhood. Peaches might go for a few years before they die, but apricots won't make it out the gate.

For peaches, I do mounds. Mounds (terracing) is standard practice for soils w/ poor drainage. I do think the roots go beyond the mounds. A commercial peach orchard close to here has trees in terraces still productive that are 10 years old.

I've lost so many peach trees, I won't plant one unless it's in a mound.

EMLA 7 is not too fond of clay soils....I would pick P18, MM111 or B118 for clay.

Apricots thrive in my heavy soil....it is mostly clay but like I said it is red in colour native to the mediterranean. I don't know how they thrive but they just do here is an attachment from wikipedia of the soil type I have. The soil is called 'Tera Rosa'

Here is a link that might be useful: Tera Rosa

Wow thanks for all the feedback! I was kind of down yesterday after the initial results of the drainage test . . . but now feeling a bit better knowing that there is a good amount of experience out there in dealing with this kind of issue.

scottfsmith - To clarify, I started the drainage test yesterday afternoon. Today I looked at the hole again and it had drained a total of 6 or 7 inches in 24 hours. I don't remember getting much rain lately but it also hasn't been warm and there isn't much vegetation (basically just grass) in the area to soak up the rain we do get once a week or so. According to my observations, even in the fall this area gets at least 6 hrs of full sun per day. When digging the hole I noticed an earthworm a few inches down. It could be that just this particular area doesn't drain well since it is not on much of a slope or maybe I'm doing this test during the wrong season. I'll probably test more areas
soon.

olpea and dirtslinger - How tall are the mounds you're planting your trees on?

Also, my mental picture of mound is basically like the second pic on this Dave Wilson link http://www.davewilson.com/homegrown/BOCpix/compact_orch.html
Making dirt mounds sounds like a much less labor-intensive solution than building actual raised beds out of wood or rock. I'll probably be planting 20 or so trees in row arrangements.

mrtexas and dirtslinger - As for using amended soil, which to make mounds I would pretty much have to add non-native soil in some way since I don't want to make a big pit in the yard, I'm envisioning using something like:

- half native clay and half "imported" loam in the above-ground level part of the mound
- then just native clay below the mound
- loam in the very bottom of the hole (it would be pretty deep so that if there is a bath tub effect it would not affect the tree's roots right after planting)

Which county are you in Maryland. I live in AA county and our soil is sandy not clay. I have no problem with poor drainage. But as you know in sandy soil you have to water a lot if it does it rain. Also in sandy soil you have problem with ants. They love sandy soil

I should probably mention that I've installed orchards on mounds in many sites over the years although not any in a soil exactly like yours. I've been doing it for about 30 years.

I use to have a deal with a commercial apple grower where I was growing nursery trees between apple trees in recently planted rows. The soil was very much a clay (clays are by no means all equal, by the way) and in fall and spring the water usually pooled up on the surface.

It was hard for me to believe at first that his orchard did so well without any ridging (the commercial equivalent of mound planting). But the water would recede by the time the trees began budding out and the trees did fine. He had trees on 26, 7 and even 106.

The point is that if I'd done the test you mention this time of the year I wouldn't have had to bring any water- it would already be there and it wouldn't have drained at all. The state of the soil during growing season is the thing.

This isn't to say disregard your test results, only that to really know the situation you'll have to check back in mid spring.

Trees grown on mounds properly constructed tend to establish more quickly on most soils as long as you don't have a much coarser soil on top of a finer one and allow trees to suffer from drought. Even worse would be putting a finer soil over a coarse one and drowning the poor things.

Often when you use a back-hoe to construct pits some of the trees will tend to tip over in heavy winds, even when drainage is ok- the mounds tend to function as an anchor.

Lind,

I'm pretty sensitive to drainage because I've lost so many trees to it. A few years ago I got tired of pulling out dead trees, so I installed a field tile in most of the orchard area. It drains a lot of sub-surface water into a neighbor's pond. The tile stopped trees from dying but many trees still weren't thriving, so I've been slowly converting more trees to mounds. It's just what I have to do here. When I pull one out, I build a mound if I plan to go back w/ a peach.

In my area, which may be different from MD, the soil stays wet from about Nov. thru June of the following year. It's the months of April, May, and June that the soggy soil does the trees in.

In the past I've made my mounds out of regular native soil because it's free. This has worked very well for me. Below is an old photo I took this Spring. The tree directly to the left of my son was just starting it's second leaf/year. The tree in the mound on the right was also starting it's second leaf. However, the one on the right was not in a mound the first year and suffered stunting. So last fall, I dug it out, built a mound, and replanted. This picture was taken before either tree had put on any appreciable second leaf shoot growth. Both trees were the same size at purchase (bout 3/4"). My other trees in mounds perform similarly.

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Lately, I'm running out of places to dig, so I've been experimenting using wood chips as a base and putting soil on top as the growing medium. By the textbooks, this is a no no. But like I say, this is an experiment.

This week I just got through building 10 more mounds for more trees. Rented a Dingo to build the mounds. Have 18 peach trees coming for next season, and have a mound for every one.

Putting soil over wood chips should be not problem at all if you have sufficient soil above. I've heard of people planting raised mounds for vegetables where wood chips were their base and getting amazingly good results and years ago I planted plum trees over a similar base. The trees loved the aeration created by the breaking down wood. It just means you'll have to work harder to maintain the mounds as the chips shrink.

It is when you mix the raw wood directly with the soil that you run into problems, and I'm not at all sure it's only N deficiency at play. I think there's also the issue of the rapidly decaying wood sucking O2 out of the soil and replacing it with carbon dioxide- not a good atmosphere for healthy roots.

Good to know. Thanks.

I've wondered about the settling. Did it cause any problems on the plum trees because of root adjustment/bending due to settling?

I have seen trees planted in orchards in raised rows where the native soil drained poorly. Just have some soil trucked in and make mounds 3-4' wide and 2' tall and as long as you like.

Regarding rootstocks -- and I am no expert, but I did some reading and got great advice here prior to planting in my WV clay soil a couple of years ago:
- The best use of M.27/EMLA27 is containers, or a sandy loam soil where there is little competition, because it produces a very dwarf tree (20-25% normal height), with smaller fruit size also. "EMLA" refers to a virus-free clone of Malling stock.
- M.26 produces semidwarf trees and is NOT recommended for clay or wet soil. (Don't confuse M27 and M26!)
- Bud 9: Fully dwarf trees, tolerates wet soils well, will need permanent staking.

My apples are on Bud 9, Geneva 16, and Geneva 11, and they all seem to be doing well so far. My pears are on Betulaefolia, except for one on OHxF 333 that is kinda puny -- since it's only one, I don't know if it's the location, the tree, the rootstock, or something else that's to blame. The other trees all look great but they're too young for me to say anything with certainty.

Good luck!

Here is a link that might be useful: Cummins Nursery rootstock descriptions (scroll down)

Olpy, the shifting is gradual and presumably beneficial in keeping things loose. The original intensive gardening raised bed theory was supposedly based on the observations of a Frenchman who noticed that shrubs and trees tended to grow faster when rooted in areas with "gradual" landslides.

When I started raised bed vegetable gardening about 40 years ago no one I knew did it with retaining walls of wood. The idea is to let the soil break away a certain amount every season and you throw it back up every spring- essentially duplicating the conditions of areas where the land is sliding.

I still grow my vegetables this way and my peppers got 5' tall this year.

The plum trees shot up like rockets and are still thriving almost 40 years later although the wood is long gone I'm sure. They weren't grown on mounds though as the soil is sand.

Mary, thanks for the info on M26 not liking wet soils, I never heard that one and thought MM106 was the only one to not put in a wet spot. Googling I found the ARS in fact has a table which lists tolerance of wetness for many apple rootstocks, see below. Note it is also negative on Bud 9 for wet situations. In fact the only dwarfing stocks listed as OK for poor drainage are G11 and G30.

Scott

Here is a link that might be useful: ARS rootstocks descriptions

olpea - thanks for posting the picture, it is very helpful!

harvestman - thanks for recounting your experience with the poorly drained orchard, it gives me hope!

scott and mary - the rootstock info is great . . . now I'm thinking that G11 or G30 would be the way to go for apple rootstock just to be on the safe side.

foolishpleasure - I'm in Montgomery County.

I guess I will be monitoring the moisture levels, especially next spring when the growing season gets going . . . but now at least I have some ideas in mind if the drainage does end up being consistently awful.

If anyone has anymore suggestions for apple, pear, or plum rootstocks (particularly dwarfing ones) that seem to tolerate wetter soils please let me know!

Finally, several nurseries promote using semi-dwarfing rootstock and using summer pruning to control height. However, I'm pretty sure that I read that this is not a good strategy in fireblight-prone areas like Maryland. So I guess the question is, yea or nay to summer pruning?

If there isn't already fireblight in the orchard by summer I don't see why summer pruning wouldn't be a good thing. Trees are supposed to be infected in the spring and the more vigorous they are the more susceptible. Summer pruning decreases vigor. To be safe, I'd prune only during dry periods.

To be honest, in my own experience I've seen FB infections that seemed to have entirely materialized during summer months. These infections don't originate at pruning cuts, however, but at the base of annual (young) shoots. The sperts at Cornell haven't been able to adequately explain this to me as FB is supposed to originate in flowers- brought there by bees.