Awakening trees are amazing machines


There’s some big machines in your yard waking up. They’re your trees! It’s amazing to follow what goes on inside trees as they wake up and they don’t make any noise.

I asked Dennis Swartzell of Horticulture Consultants to take us through the steps.

Swartzell started with the roots and trunk. They are the storage system where energy accumulates. Swartzell calls this system the “bank.” He considers the energy to be “money.” The bank has some energy stashed away from last season so it isn’t empty for the new season. The bank is eager to dispense this energy throughout the tree as it springs forth.

As the soil warms the roots start mining for water and nutrients to put in the bank. They metabolize into energy (sugar, starches and other nutrients) in preparation to facilitate the new growth and to be dispensed as needed.

The arborist says the leaves begin unfolding. They send signals for needed energy, placing a great demand on the bank, but it’s more than willing to meet the unfolding leaves’ demands as they will replenish the energy as the new leaves mature. Swartzell calls the leaves “factories” because there is so much going on within them.

Within these factories is the most amazing chemical reaction to take place on this Earth. Swartzell said, “It is from these factories/leaves ‘all’ food comes from. It’s called photosynthesis!” This amazing reaction brings carbon dioxide from the air and water from the roots to make sugar and starches and gives off oxygen. We should be deeply grateful to these factories for this oxygen we breathe.

The buds that developed last year up in the crown awaken. Scales covering these buds to keep them from drying out and from freezing fall away. The bank responds to their needs and sends up the much needed energy.

As the buds awaken, this causes them to grow and stretch into twigs and they too stretch to become sites for leaves, Swartzell said. As the leaves open, they now produce energy for the bank and an equilibrium begins to take place between the bank and the tree’s energy demands to bring about a more self-sufficient tree.

Now it’s the trunk that grows, swelling rapidly. Within the trunk are a series of huge tubes or straws that allow for rapid movement of nutrients to the trunk. This results in the trunk expanding in girth. Swartzell calls this new growth spring wood. As the season progresses these straws diminish in size as they’ve met their demands.

The tree rings form between the old and new wood.

With the increase in girth, the bark starts to stretch and in some cases cracks. A corky tissue develops to fill in between the bark cracks to keep infection out.

Now the roots go into action. They are out searching for more water and nutrients for a larger tree and the central bank is also getting bigger. That’s right, the bank quickly comes to the aid of the expanding roots.

There are four functions Swartzell said we need to be concerned about: They are water, sun, fertilizer and pruning.

Water is crucial: It makes up a major portion of the tree to carry out those important functions. If trees can’t get enough water, salts build up and place a real stress on the tree, causing an energy depletion.

Always deep soak your trees to flush away the salts. This provides an environment for roots to extract those much needed elements to produce energy.

Sun is also crucial: If your trees can’t get enough sun, energy production diminishes, resulting in fewer factories and a less desirable tree.

Pruning, a big problem: If we remove a large number of factories/leaves, it prevents them from producing enough energy for the tree and it slows down root growth to keep the tree growing.

Overfertilizing: Anytime you apply fertilizer, you are applying salt. The excess burns the roots and the plant must work harder, which really taxes the tree. So more is not better.

Swartzell concludes by saying, “People think of fertilizer as an aid to improve plant health but it’s not always the case. Trees want adequate nutrition, but not in excess.” To overcome fertilizer burn, apply large amounts of water to flush them away.

Linn Mills writes a garden column each Sunday. You can reach him at linnmillslv@gmail.com or call him at 702-526-1495.