I am on the phone so my answer will be brief.

It just depends on what your plan is. Creating a raised bed around a tree is a bad idea. BUT, check out all the grass growing under live trees. Obviously if grass grows sone flower or other will.

What kind of plans do you have more specifically?

you will not harm the tree in any way.. by being close ..

the issue is disturbing the roots by adding soil on top.. driving machines in there ... etc .. and no tilling.. ever ...

but the real issue.. from the garden side is.. what kind of tree and what kind of plants ..

e.g. maple trees are the bane of hosta gardeners ...

so.. as noted.. whats the idea ... before we go off on unimportant side issues...

ken

I'm not sure where you read that planting under a tree would kill it - it is simply not true! Trees growing in the natural environment routinely have other, smaller plants growing under them. Even in heavy forests, there is always undergrowth!

As Ken stated, raising the soil level under existing trees can be harmful but in virtually all cases, underplanting them at the same soil level is not an issue. Some trees dislike much disruption in their root zone (Japanese maples for example) so it is best to plant things that will grow happily without the need for division or replanting. And other trees have such aggressive root systems that it is a challenge to get things to thrive within the spread of their canopy or even further. But most trees are very happy with accompanying shrubs or perennials and groundcovers in close proximity.

In a small urban or suburban lot, I dislike trees planted plunk in the middle of the lawn. They have no sense of place and look like after thoughts. Plus lawn up to the base of a tree can be a hindrance to successful establishment, not to mention the potential for string trimmer or mower disasters. A good sized bed with complimentary underplantings give trees context and anchor them into the landscape.

From personal experience I can tell you that cherries have a fibrous root system that sucks all nutrients and moisture and makes it extremely difficult to grow many plants. Magnolias have a very thick root system that makes it impossible to dig/divide bulbs or plants once planted, though they do grow fine. Under my magnolias I have small bulbs and Geranium 'Biokovo' and G. 'Karmina' as groundcovers. I also plant under Ironwoods and an enormous sycamore.

It is a rare residential property, in Central Texas, that does not have trees in the front yard for shade. The problem most us have, in planting around and under them, is that the soil isn't suitable. I wanted a raised bed around a live oak, and discussed the project with the local Texas A&M extension service. I was assured that adding soil around the tree, to a depth of 8", would do no harm, provided it did not contact the bark. So, I constructed a bed, 8" deep and 8 ' wide, around the tree, about 8" in diameter, at the time. I also put a collar around it, giving it about 4" clearance from the trunk. That was about 15 years ago. The tree now measures 20" at the base, and is healthy. It outgrew the collar years ago. Only thing, I have to pull up a lot of small oak plants every year. Not sure whether they're coming up from roots or acorns.

the problem is.. when you dig a hole.. you cut tree roots ... the response from the tree.. is to grow new aggressive feeder roots into the hole you just dug ...

so .. with an aggressive tree... in a year or two.. it MIGHT strangle your babes ... most often sucking all the water away from your plants ...

so the trick.. is to dig a very small hole... never amend that hole.. never fert that hole.. and mostly bare root the plant you are putting in that hole.. and broadcast the water.. rather than just watering the hole ....

we are basically trying to hide the new plant in that hole.. rather than making the hole so 'good' .... the tree will invade it

i dont know what you read... but its hard to dig in the first foot or two of a tree .. and that is why i would never plant that close .. also.. tree trunks prefer to stay dry.. and having plants too close.. can keep them too wet ...

i am not familiar with a single tree you have ... lol.. whats that all about .... oh.. you are z8 ... except for the weeper.. and i dont know why you would plant under that unless you shear it to high bangs ...

go for it ... if you fail.. you fail.. but you wont harm the tree ...

good luck.. and have fun

ken

I would not plant anything under the fruit trees. I really think you may regret it later.
Fruit trees need to be sprayed for pests, fruit trees need fertilizer, fruit trees drop their fruit, which you will need to pick up. What ever you need to do to the tree(spray/fert) will happen to the under plantings as well. Some times under plantings can cause the fruit trees to get pests they would not usually get. Aphids can be a big problem.