Question: I planted a Maple tree a few years ago. It's about 15 feet high now. Recently, I noticed that there are many roots near or above ground level. Is it because it's not getting enough water? We have bad soil, very clay like. Can I change the watering technique to help it grow more roots deeper in the soil? Will the tree be more likely to come down in bad weather because the roots are not deep in the ground?

Answer: Many people believe that tree roots are supposed to be way down in the soil, under all the other plant roots. Instead, many trees have most of their roots just under the grass. Roots need air and water and in clay soil, most of the air is near the surface.

If the soil is good and there is moisture and air one or two feet down, then the roots will also grow there. They will still grow near the surface, even when some roots from the tree are growing deeper.

Whenever you build a home, ask for as much topsoil as you can afford. The deeper it is to start with, the better your plants will grow in the future. If you add more water to clay soil it just runs off, so changing the watering technique won't help.

Maples tend to be pretty secure, even when they have shallow roots, but if the area for them to grow is limited by buildings, sidewalks or other paved areas they may not be able to stand a storm in the future.

Roots on trees do not suddenly start growing near the surface. They start out small and near the surface and then over the years they grow in diameter. As they expand, they seem to just pop up one day, but they were there for a long time.

Roots that enlarge and begin growing above the grass will cause problems for the lawnmower. Be careful not to damage the roots with the mower. Damaged roots can be infected by soil borne fungi and bacteria that can quickly kill the tree. If you want to keep grass under the tree, you can add a couple of inches of topsoil to the lawn area each growing season to try to keep the grass above the roots.

As the roots begin to show in the lawn it is often better to change the lawn to ground cover and perennial plants. Shallow tree roots compete with grass for water and the tree will also shade the lawn. There are many ground cover plants that are tolerant of both shade and less water than grass would prefer.

Question: I have a problem with my lawn in the areas where trees were removed years ago. The stumps were ground out and after about four years of filling, sodding and seeding I still can't get the grass to grow properly in this area. (Some spots are still sinking, too!) Weeds seem to do perfectly well!

Answer: It is time to start over with good soil. It sounds like too much of the stump was left or too much of the sawdust was left in the soil after the stump grinding. A large stump can be several feet in diameter. The main roots can also be quite large and they will spread out for several more feet.

The grinding process will leave a very large pile of loose soil mixed with wood fibers. If the machine did not dig deep enough or wide enough around the stump it will not have removed all of the solid wood. As that wood and the wood fibers left from the grinding process decay away, they will take up less room and the soil will settle.

Bacteria and fungi do the work of decaying the wood fibers. As the wood fibers are consumed, the microorganisms need other nutrients, especially nitrogen. The decay organisms have better access to these soil borne nutrients than the grass roots, so the grass does not grow well. There are many weed plants that can grow in soil with low levels of nutrients and they will grow better than the grass. Fertilizing might help the grass. There will still be the settling problem.

After a stump grinding, the leftover sawdust and soil mix should be removed. It can be spread out and used as top-dressing mulch in flowerbeds. Add a balanced fertilizer (10-10-10) to the mulch to help it decay. Any remaining stump pieces or root pieces should be removed. New topsoil should be used to replace the soil dug out of the hole.

Email questions to Jeff Rugg at [email protected]. To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.

Copyright 2016 Jeff Rugg, licensed to Creators Syndicate.