Plant In Square Holes

David Trammel's picture

Makes sense once they describe the problems.

Why you should plant trees in square holes

"Traditionally, trees were planted in round holes, perhaps because their trunks are round, as is the spread of their canopies. It was just one of those seemingly obvious, unquestioned assumptions. But here’s what happens to the tree’s roots when you plant them in a round hole, especially one filled with lots of rich compost and fertilizer, as the old guide books suggest. The little sapling will rapidly start growing new roots that will spread out into the rich, fluffy growing media, giving you excellent early success. However, once they hit the comparatively poorer and compacted soil at the perimeter of the hole, the roots will react by snaking along the edge of the hole’s edge in search of more ideal growing conditions.

Eventually, this spiralling action around the limits of the hole will create a circular root system, with the plants essentially acting much as they do when grown in a container. Once the roots mature they will thicken and harden into a tight ring, creating an underground girdle that will choke the plant, eventually resulting in the severe stunting and even death of your treasured tree.

The very simple and counter intuitive act of digging a square planting hole will dramatically reduce the chances of this happening. This is because systematic planting trials have shown that roots are not that good at growing round corners. When they hit the tight, 90-degree angle of your square hole, instead of sneaking around to create a spiral, they flare out of the planting hole to colonise the native soil."


I know from looking at the root structure of my planters at the end of the season, that yes plants will continue to grow roots until they fill up the container. Perhaps I'll try planting my vegetables this year in more loosely dug holes and instead of filling them back in with a handful of compost, just use the dirt instead.

alice's picture

It might be different with annual veggies you're planting out. How do you generally feed them? There is what agronomists call the 'increment of fertility' that comes from the soil's own processes each year but veggies will grow a lot more if they are fed carefully. Steve Solomon's book with Erica Reinheimer 'The intelligent gardener' describes a process for soil analysis for the beginner, to find out what is in the soil you grow in, and also contains a Complete Organic Fertilizer recipe which is a plant food mixture you make up from your local industrial process by products, don't know if you have come across that?

mountainmoma's picture

Yes, you should refill that transplant hole with the surrounding soil. And, you shouldmake sure the transplants are not root bound. Actually, some plants, like tomatoes dont care too much, but brasicas need to be set out before they get root bound, or they may never do well. Another thing to do is to of course shake off all the potting oil from teh transplant roots, or soak for a short bit, or at least run your fingers over the outside of the root/dirt and lossen it up. You do not want the plant to think it is still in a pot.

If I have failed to start a certain brassica in time to transplant, and buy a few from the store, I gently lift one of the little brocolli plants out of the six-pack to look at the root area, you can generally do this easily and gently by lifting up on the stem at soil level. If it looks root boud, I do not buy that. It is much better to have a smaller brocolli start that has not fully filled up the root space

Blueberry's picture

Friend planted 20 acres of pecans in 1982. The holes were 4ftX4ftX4ft square the back fill had 1cu ft of peat moss added to the soil. The trees were under drip irrigation. Talk about massive trees most are now 30 inch dia at the trunk. The planting guide was from The University Of Georgia..

David Trammel's picture

That's one thing (among many) that I've neglected. Given the small size of my garden I usually dump a bag of good compost on the bed, slightly dig it into the upper soil and plant. I'll have to do some research on the subject. Not 2020 but in 2021 once I'm at my sisters and have begun setting my new raised beds up, I'm going to need to start developing that soil.

If I can get some set up by the Fall, I'd like to try and use all the dead branches she normally gets during the year, broken up and into the base of the beds as sort of a hugelkultur, then pile the leaves on top of it as they accumulate.

Blueberry's picture

Fertile Soil by Robert Parnes, Ph.D. A growers guide to organic & inorganic fertilizers. Link to a PDF print copies are like gold!!!

I turned a quarter-acre of hard packed clay into top soil (upwards of a foot deep in spots) with dead leaves.
Collect ALL the neighbors leaves that they leave out on the street for collection.
Pile high on every part of your yard that isn't grass.
Repeat every year for decades.
Your soil will improve.
You can collect loose leave with a lawn-cart and a rake (character building for surly teenagers). No one ever asks.
Or, if your neighbors bag their leaves in those big brown kraft bags, collect them all and dump then where you need leaves.
I've collected bags 'o yard waste for twenty years and no one has ever asked my why I'm stuffing them into my little red sedan and driving off with them into the sunset.
Or, you can contact your municipality, find out what they do with their leaves, and have a tractor-trailor load dropped off! We did this in South Carolina. It took weeks to move all those leaves but it really jump-started my soil production.

Don't throw away your neighbors' soil fertility.

Teresa from Hershey

lathechuck's picture

Last year, I tried burying my fruit-tree trimmings, mostly thinner than my thumb, under my vegetable plots. I dug out about the depth of my shovel, maybe a foot or so, piled it about half-full of sticks, then put dirt back on top. Whether or not it's helped the soil quality, I don't know, but I need to dig that plot every year to cut the fruit tree roots that would like to take water from the veges, and finding the sturdy sticks down there didn't make that any easier. I should have left a buffer zone for the root trimming.

David Trammel's picture

I wonder how much this disrupts the soil ecology. As I understood it the bacteria differs at the top level from the level at one foot.

An idea in the back of my mind a bit unformed is, to put a center trough in your bed, which you put the sticks, twigs and leaves in to decompose. The grow veggies on either side. It wouldn't be composing so I don't know how effective the nutrients would be at getting into the roots of the veggies. Maybe mushroom fungus seeded among the sticks? Would that help break the organic matter down, and maybe provide some mushrooms too. In the center they might be shaded by the veggies too.

alice's picture

Solomon and Reinheimer's method goes beyond compost because of specific experiences Solomon had with his family of exacerbating mineral imbalances by applying compost made locally, which is why he recommends soil analysis.

Here in the UK I have to order organic peatfree composts and get them delivered, the ordinary local garden centre ones have now all been taken over by companies who add inorganic nutrients to the compost. Fine if that's what you want but I believe that the highly soluble nitrates in conventional fertilizers work against a healthy soil ecology and I would rather try to work with the soil microbes. I have an organic fertilizer composed of oilseed meal (the leftover after oilseed is pressed for oil) powdered bonemeal, kelp meal etc.

ClareBroommaker's picture

Hmm, that's an interesting thought about locally made composts exacerbating imbalances.

To David who gardens within 20 miles of me, I have this idea which comes to mind because of the satellite images alice posted elsewhere. Go down to the Mississippi River below the junction with the Missouri River. Get a bucket of Mississippi mud and you will be getting minerals gathered by the Missouri, the Mississippi, and the Illinois rivers, minerals which may be different than what is in your native (or purchased soil). Add that into your garden beds along with your purchased compost (which around here are mostly made from tree wood and leaves). Maybe you can understand it as your garden having been remineralized from the annual spring river flood.

In the main part of my vegetable garden I probably have incorporated about 0.5 square yard of river mud because we removed an old barbeque pit that sat on a thick concrete pad. That left a crater in the garden which we filled by bringing home a big bucket of Mississippi mud every time DH and son went fishing one year. Now after 15+ years it's indistinguishably mixed with the in situ soil.

The benefit of square holes is SO obvious after reading your initial post - I can’t believe i haven’t heard of it sooner. I have always been careful to roughen the sides of the hole and loosen the roots, which I think helps.

I often come across container shrubs that already pot bound with circling roots. (Sometimes this is my fault for procrastinating on planting them.) My conclusion is to buy and plant small rather than big.