Tomato Plant Roots

Q: My neighbor grows her tomatoes in pots about 1.5' deep. I always heard that the height of the plant above ground should be equal to the height below ground - the roots.

Yet she gets better vegetables than I do and I plant in the soil. Her plants grow over 3' tall but obviously the roots can't.

Please advise. (Now that I think about it, I can't imagine our tall trees having roots going that deep - maybe she is right)

A: My guess is that the quality of the soil is making the difference between the tomato plants.

If you are growing in native soil, it may not be friable enough or rich enough , even with amendments.

Your neighbor is probably using a good potting soil, which is better for tomato plants than hard soil.

As for depth, roots do not grow as deep as a plant is tall. As you've observed, this would mean that tree roots would be dozens of feet down, and I assure you they are not.

Instead, roots grow outward, and can be several feet deep in some cases, but they're rarely down more than 5' around these parts.