When do tree roots grow

Root growth from container and field grown nursery stock: Roots in field grown root balls can be oriented primarily down as shown in Figure 1 top , or they can be oriented horizontally and down as shown in Figure 1 bottom.

This large difference in orientation can impact how roots grow into landscape soil. Figure 1. Field grown root balls. Top shows roots oriented down, bottom shows many horizontally oriented surface roots. Top photo courtesy Keith Warren. Figure 2. The new roots that grow from the cut root ends that are deep e. Only a few adventitious roots developed on this tree after it was planted into the landscape. New roots grow from the tree shown in the top of Figure 1 in two manners.

Roots can either generate from the cut ends Figure 2 , or roots can grow adventitiously from the base of the trunk or base of the main roots Figure 3. Some trees do both Figure 4. Some roots growing from the cut ends grow up toward the soil surface because there is more oxygen in the shallow soil layers in many urban sites.

This can result in a root system that looks something like that shown in Figure 5. Roots grow from the tree shown at bottom of Figure 1 as shown in Figure 6. Whitcomb found, for instance, that trees and shrubs grow most of their new roots - better than 80 percent, in fact - in the fall of the year, which gives added gardening importance to the weeks that lie ahead when transplanting, watering, and even feeding can be advantageously undertaken.

It turns out that there is a pecking order for nutrients in woody plants that doesn't vary from year to year: Flowers and fruits get first choice, followed by the leaves, then the stem, and finally the roots. For instance, the trunk or stem does not increase in size until late summer. After that, the bulk of all nutrients go into putting on new root growth. Nearly all root growth takes place in the top 12 inches of soil, spreading out well beyond the circumference of the tree.

Tree roots grow rapidly when soil temperatures are in the 50s and 60s degrees F. Among other things, Whitcomb's trials also showed that there is no need to add amendments compost, peat moss, etc. In heavy soils, this can even be a distinct disadvantage.

Yet another controversial discovery: It is best not to prune either the top or the roots of a tree when it is being transplanted, other than to remove damaged material. Because many of these discoveries flew in the face of accepted industry practice, Whitcomb was at first disbelieved.

Several people set out to prove him wrong, but as the years passed no one was able to do so. Dig a hole a few inches wider than the root ball and no deeper, so that the stem is at the same soil level as it was in its previous position.

Fill in with unamended soil from the hole you have dug and firm this by watering. Don't stamp down the soil with your feet, as this can create compaction in heavy soils. Soil aeration: After planting, loosen the soil away from the hole so that the new roots can move readily into the surrounding area.

Do this by pushing a spading fork into the soil every six to 12 inches and gently rocking it back and forth. Do the same thing with established trees if you suspect the soil is compacted around the outer perimeter of the tree. Some minor root damage may occur, but this will be quickly overcome in the fall period of rapid root growth. Feeding: Late fall, after the top has gone dormant, is a good time to feed tree roots.

The soil is still warm, so the roots readily absorb the nutrients and store them there, ready for release to the rest of the tree in the spring. James Urban has definitely made his mark in the tree root world.

Still, the article would have been greatly improved, and the photos infinitely more helpful if species names had been attached to the trees in the photos.

Question: I have a Norway Maple 80 years old and approx. I am installing a new water line and it goes under the tree about 5ft down. Are olive trees typically deep rooted or not? A colleague here believes that olive trees are deep routed to allow them to grow in dry climates but my experience has been that they are shallow routed.

My experience with olives is also that they tend to be shallow rooted, but I must admit to not being an expert on olives! I do know that roots will grow wherever they can find suitable conditions. So, while trees do tend to have certain rooting habits, you will see variation depending on the planting conditions. Excellent post! Always happy to learn new things especially about trees.

Thanks for sharing this! Im thanking to the authors of this article because it was very helpful to my research on roots and if i may i would like to copy some of the paragraphs of this article and i will assure you that your work will be acknowledge. You must be logged in to post a comment.

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