Because it deals with a plant part that stays largely hidden underground, roots’ development remains an area of ongoing study for botanists. Some of the scientists that specialize in plants work to learn when and how roots grow best.
Observations that have been made so far:
As per an arborist in San Jose, a tree’s root grows the most in late spring and in the earliest part of the summer. Some species in the tree family have a root system that could keep growing in winter, if the soil’s temperature has remained above 36 degrees Fahrenheit.
Although able to survive without exposure to sunshine, roots do need nutrients in order to grow. By introducing fertilizer, a gardener can provide a root system with added nutrients. Yet the method for adding any nutrient makes a difference. Indeed, it helps to add each nutrient slowly. Some fertilizers manage to perform in a uniform fashion. Those same types of fertilizers can be applied to the ground around a tree at any time of the year.
Signals that a tree needs to be fertilized
The new twigs that form in the spring appear shorter than the ones that were observed in the past. The tall plant needs nutrients, in order to carry out the growth process, at the ends of the tree’s branches.
Like the twigs, the leaves appear undersized. Again, that reflects the absence of a substance that works to promote the growth process. A nutrient-rich fertilizer should ensure addition of that same growth-promoting substance.
Evidence of dead branches: In the absence of adequate nutrients, a tree stops sending those nutritive substances to certain branches. In the absence of such substances, the nutrient-deprived branch dies.
Dark leaf veins: A dying branch would not contain healthy leaves. A dark vein could denote the absence of specific nutritive substances. Like sunscald, the resulting damage could discolor part of the tree’s tissues.
Yellow or purple leaves: Any aspect of the environment that taxes the root system could cause the tree’s leaves to turn yellow or purple. A need for fertilizer is only one of the changes in the environment that can tax a tree’s roots.
Sometimes a homeowner grows a small potted tree, with the intention of planting it in the yard, once it has grown larger. Yet, if the pot becomes too small, the system of roots gets squeezed. That can cause the tree’s leaves to turn yellow. A squeezed root struggles to carry nutrients upward. As a result, some of the leaves at the top of the potted plant turn yellow. A reduction in the space that has been made available to a rooted system stands as one example of an environment that has the ability to tax the same rooted system.