Tree roots will surely re-invade your garden unless you put down a barrier such as metal roofing. This worked for me stopping spruce tree roots from invading a flower bed.

I am with kimmsr on this one I have had salad vegetable gardens close to Ash trees for partial shade and cooling. Just feed the trees and vegetables. Put the sun loving heavy feeders farthest away from the roots.

Curt

It depends on the type of tree. I tried to grow hostas in a large prepared bed 20 feet away from a row of birch trees. Birch trees love to run roots at the surface. I couldn't water those hostas fast enough that those Birch trees wouldn't suck the whole bed dry. I tried fighting the roots but they networked the entire bed thickly, just loving the much layer and compost. In the end I just lived with anemic looking hostas. I couldn't imagine trying vegetables under those conditions.

You water your garden on schedule which makes the roots something to go for.
There is no danger to a tree by cutting those thin feeder roots---they're replaced within weeks, die or become part of a major root system within a couple years. Larger roots may be cut by keeping to a set formulae so the tree doesn't suffer any harm. Most tree roots will be found in the top 6" - 18" of soil and any major cuts should be looked at as a possible danger to the trees' continued health. Chances are your oak tree has a tap root, or in some cases of oak, roots that are deeper than those trees that spread out more just below surface. The birch tree has such spreading roots and cutting their major sized roots should be looked at as something not to consider.
Cut feeder roots as you wish.

Putting something, such as metal roofing, buried down sufficiently to make a root turn away, is an option but generally your garden is not cultivated so deep that this would prove necessary. Just keep cutting the roots as they appear.

Move the garden or move the tree is best. But cutting the roots & placing metal roofing should work.
Oak tree do not have taproots, not like pine trees, but the oak can have root as big as the limbs on the tree.
Any time you cut a root, cut the small growing in first(farthest from the trunk).Then cut the larger, closet to the trunk end last.Do not do this & you will learn, the hard way, as I did.

Joli, oak trees definitely do have tap roots...at least, some varieties of oak. Others not so.
And, given careful considertion for how the tree takes moisture, some major tree roots can be cut.
The most often used formulae is to measure up the trunk of the tree four and half feet....measure the diameter at that point and multiply that figure (in inches) and treat that as feet X 3. Thus if a trunk were 6" across at that level, then outwards 18 feet the roots at the point can be safely cut without endangering the tree's survival or its ability to continue to take up moisture.
Considering the number of roots at the measured distance tho could cause the tree's stability to be affected.

Considering how a tree root travels, it goes pretty well where it wants and if it encounters a barrier, it simply goes around, over or under it. How deep would a barrier have to be to change the mind of roots that often come up to view the world above the surface.

They do it all the time when a tree gets in the way of construction and since the tree may be on a bordering property, such formulae is followed very carefully.

I have enjoyed the comments on the tree root invasion into vegie gardens as I was hoping for an answer, most of the posts mentioned things I had thought about and tried. However just before I clicked out I "think" i may have an answer - the only way to completely 100% ensure no roots invade your vegie garden is to not have the garden bed in contact with the natural ground level. I actually have already done this with my strawberry bed which is under 2 large Eucalyp trees (In Australia)I constructed this on some old steel fames and railway sleeper - its about 3' high and the depth of soil is still 300mm deep. I did this purely for ease of picking and maintaining my strawberries - it works a treat. so now I will try to make a similar structure so there is a air gap between the tree zone and my garden bed..

I agree with Mickscott that raised beds are the way to go. While I don't grow veggies I find it's difficult to grow anything under the coniferous and deciduous trees in my garden. I'm giving up and only mulching that area heavily as those trees quickly suck up all the water and nutrients I put down for perennials and I don't think they really need it as they have deep roots in the clay soil and will survive just fine without my input.

Even with raised beds, the roots will get in there. I have ash trees 10 yards away from the vegie garden, and find their roots all the time. The winner is a cottonwood on the other side of the road, sending in roots 50 yards away - the size of my wrist.

As well, if I leave them alone for a couple of years, the feeder roots will get so thick in the garden soil that its almost a solid mass.

Anyway, I use a machete and a hatchet, follow the root back towards the tree out of the garden, and whack them back when ever I find them.

..
Build a raised bed on top of pavers. It still drains and worms will make their way up into raised bed (try that with a compost bin and after the rains it's worm city). The pavers will also keep the burrowing vermin out.

to sense
..

Hi,
I have a whole yard of fruit trees including fig and avocado trees. I made a deep bed planter with 2 stackable slatted compost bin frames (no tops of bottoms). The bins are stacked directly on the ground.

1. Make a layer of brick on the ground.
2. Place a tub on the brick. It has the same features as the earthbox: Overflow holes, input pipe, support for the platform where soil is piled onto. In addition include 4-5 terry cloth strips to wick up the water from the tub and have them ready to come up vertically through the soil. Thread a black tubing pipe (1/4-1/2 in diameter) from the bottom of the tub and through one overflow hole to the outside of the slatted planter.

Test the overflow system:
Fill the tub water reservoir through the input pipe and check to see that the black tubing is removing excess water from the tub when it is full. The water should be dripping out through the black tubing and be visible from the outside of the planter. A small amount of water might spill over the tub onto the bricks and then to the ground where the tree roots are.

3. Make a platform around the tub to create a 2nd air layer.
This platform will have a grid (cut from chicken wire) over it and the grid will be lined with landscape cloth. The height of the grid will be the same height as the platform inside the earthbox type tub. Use lengths of 4-5 in drainage pipe laid down horizontally or in short segments and placed vertically as shown in the picture.

4. Carefully shovel soil into the planter and fill all void spaces.
5. Plant the vegetables and mulch heavily with redwood compost.

This post was edited by jyn510 on Sun, May 11, 14 at 2:40