Wires_Guy_wires
Imperial Masterpiece
Tap roots can be difficult to beat.
Shallow pots are a good start; if they can't dig deep, they will not dig deep. At first this taproot will still form and grow sideways, but it'll degrade within a year or two.
Girdling is a good option, I just placed a bunch of zip ties around the fattest roots of my oaks (5-6 years old). As they grow fatter, they'll constrict themselves and naturally die off. This does two things: it gives the other roots time to form, and because it's such a slow process the tree will generally adapt the rest of the root system to grow a bit faster resulting in a more evened out development of the root system. Use the fatter zip ties, because the small ones can be overgrown. Tile growing is a good option too, but you'd need to take good care of watering since there's just a shallow patch of soil above the tile.
Removing the tap root entirely can be risky in young material, it's always good to wait a year or two so that the rest of the roots have time to develop.
Shallow pots are a good start; if they can't dig deep, they will not dig deep. At first this taproot will still form and grow sideways, but it'll degrade within a year or two.
Girdling is a good option, I just placed a bunch of zip ties around the fattest roots of my oaks (5-6 years old). As they grow fatter, they'll constrict themselves and naturally die off. This does two things: it gives the other roots time to form, and because it's such a slow process the tree will generally adapt the rest of the root system to grow a bit faster resulting in a more evened out development of the root system. Use the fatter zip ties, because the small ones can be overgrown. Tile growing is a good option too, but you'd need to take good care of watering since there's just a shallow patch of soil above the tile.
Removing the tap root entirely can be risky in young material, it's always good to wait a year or two so that the rest of the roots have time to develop.