Tag Archives: Plant Physiology

Why Topping Your Trees Is Harmful

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This is what your tree should never look like. This is the result of the abysmal practice of topping. Other names for topping include: heading, tipping, hat-racking, and rounding over. Besides the ugliness of the topped tree and the cost of having someone come do it every year, there are other reasons to not ever do this to your tree.

The International Society of Arboriculture states: “Topping is perhaps the most harmful tree pruning practice known. Yet, despite more than 25 years of literature and
seminars explaining its harmful effects, topping remains a common practice.”


There are several things that topping your tree does to harm your tree:

Stresses the tree – Making large cuts can remove more than 50% of the leaf bearing crown of the tree. In an effort to recover, the tree produces rapid growth of new leaves. As a result you leave a weak tree with large pruning cuts which provides a perfect situation for diseases and pests to attack the tree.

Decay – Correct pruning of a tree allows the tree to compartmentalize the wound and close it. Topping leaves no way to close the wound created by leaving no branches nearby to carry resources to the point of the cut.

Weak Limbs – Due to the stressful production of new branches after topping, the newly formed branches are much weaker than a properly formed branch. This increases the risk of breakage through windy conditions.

While topping is still commonly practiced, it is not necessary. If you need clearance from utility lines you can prune in a responsible way to satisfy clearance and still provide a way for the tree to heal itself. Proper planning of tree species and placement will help you to avoid these problems in the first place.

Fruitless Mulberry trees have a lifespan of 50 years, but generally only live for up to 25 years due to topping. Topping is much easier than properly pruning a large tree and provides yearly income for those performing it, but properly pruning your tree will result in a healthy tree for much longer.

Why Your Yard Needs Mycorrhizal Fungi

mycorhizes-01

A mycorrhizal fungi is a symbiotic relationship between a plant and a fungi. This network of mycorrhiza can span miles and miles within one small cubic foot of soil.

Why Does This Matter?

This symbiotic relationship allows plants to draw nutrients and water that the root system itself would be incapable of. It also allows for the plant to resist disease and toxins. Mycorrhizal fungi can also be a great factor in drought tolerance, yield of fruit or flowers, prevention of soil compaction, ability to withstand the sowing process for seeds or transplantation, and overall microbial activity in the soil.

How Do I Encourage Mycorrhizal Relationships?

Here is a list of things that harm mycorrhizal relationships:

  • Erosion
  • Road and Home Construction
  • Leaving Soil Bare
  • Tillage
  • Fertilization
  • Fumigation
  • Chemical Treatment of Soil
  • Removal of Topsoil

These things can completely eliminate the mycorrhizal relationship in your soil.  This can leave plants in your landscape with a significant need for maintenance and upkeep.

You can add mycorrhizal fungi to your soil by using organic fertilizers that contain the correct fungi, or you can use a mycorrhizal inoculant such as those found at www.mycoapply.com .

Continued practices of not using chemicals, covering the bare ground that you can with mulch or other plants, and not tilling or leaving the soil to erode will keep the mycorrhizal fungi at home and not disturbed.

Having mycorrhizal fungi in your soil is the cure to a problem you didn’t know you had. These little guys will be personal caretakers for your plants so you can direct all your energy somewhere else.

 

Misleading High Desert "Hardiness Zones"

In the High Desert we can range anywhere from USDA zone 8a to zone 9b. The 2012 Sunset Western Garden book currently places us at Sunset Zone 11, though we had previously been placed at zone 10 in the 2001 version. This leads to plenty of confusion when choosing plants to beautify our landscapes. I hope to demystify this widespread confusion.

USDA Hardiness Zone Southern California

What does “hardiness zone” mean?

A hardiness zone is an estimated amount of days that a location experiences a certain level of cold temperature. A plant with a hardiness zone of 7 means that it will survive the cold winters of areas that have been estimated as zone 7.

What “hardiness zone” does NOT mean

Hardiness zones do not take into account the high temperatures that the zones might experience. This is where the High Desert is an anomaly. We experience high temperatures like any other desert, but we also experience freezing temperatures in the winter. This makes for difficult interpretation of plants ability to survive.

AHS Heat Zone Map

The American Horticultural Society has begun the implementation of a heat zone map to indicate a plant’s ability to handle a certain amount of days over 84° F. While not currently available, this will be the indicator that makes plant selection more accurate for us. You may see this mentioned on a few selection of plants sold by Monrovia Gardens at big box stores.

Microclimates and what to consider when growing “borderline” plants

If a plant is in USDA hardiness zones 3-8, you can deduce that they can get very cold, but heat might be an issue for us in the High Desert. This might not be a fantastic plant to place in the middle of your dirt lot with no protection from the afternoon sun or the harsh wind. This would be a plant that would benefit from afternoon shade from a building or larger tree.

On the flip side, if you have a plant that is great for USDA hardiness zones 9-12, you can deduce that heat and sun shouldn’t be a worry, however cold tolerance may be an issue. This can be handled by planting it near a building that retains heat. South facing walls, retaining walls, bricks, asphalt, etc. can retain a significant amount of heat that will help nearby plants to deal with the cold nights. Mulching the plants can help as well. As a last resort, covering or protecting plants on nights that might drop below the prescribed cold tolerance can help the plant to make it through the colder nights throughout the winter.

Microclimates in the High Desert that kill borderline plants

The High Desert has plenty of climate issues that keep plants from growing that might otherwise thrive. Here is a list of things you might want to think about protecting your plants from:

  • Wind

  • Afternoon Sun and Heat

  • Cold Nighttime Temperatures

  • Alkaline Soil

Wind can be dealt with by sheltering plants with a windbreak (plants, fences, walls, buildings, etc.)

Sun and heat can be dealt with by planting under trees, balconies, overhang on house, pergolas, etc.

Temperatures can be dealt with through planting near buildings, south facing walls, asphalt, brick, retaining walls, and porches.

Alkaline soil can be handled by amending the soil at planting time with peat moss and acidic fertilizer, and by fertilizing regularly with acidic fertilizer throughout the growing seasons.

Specific Plants and Their Needs

Japanese, Silver, Autumn Blaze, Trident and Red Maples all need wind protection and if possible some sun protection

Azalea, Hydrangea, Camelia, Japanese Maples, and many more need acidic soil and sometimes sun, wind, and cold protection.

Plants that break the hardiness zones

Here is a list of plants that supposedly do not grow here based upon hardiness zones. I have witnessed all of these trees growing in the ground in Apple Valley, CA in several locations.

The High Desert zones as stated by USDA Hardiness Zone Map and Sunset Western Garden Book:

USDA Zone: 8b – 9a

Sunset Zone: 11 (previously listed as 10)

California Pepper Tree

  • USDA zones: 8-11

  • Sunset zones: 8, 9, 12-24

Coast Redwood

  • USDA zones: 7-9

  • Sunset zones: 4-9, 14-24

Deodar Cedar

  • USDA zones: 7-9

  • Sunset zones: 3B-10, 14-24

Crape Myrtle

  • USDA zones: 7-10

  • Sunset zones: 2-10, 12-24

Colorado Blue Spruce

  • USDA zones: 2-7

  • Sunset zones: 1-10, 14-17

Lantana

  • USDA zones: 8-11

  • Sunset zones: 8-10, 12-24

Pineapple Guava

  • USDA zones: 8-10

  • Sunset zones: 6-9, 12-24

Lily of the Nile – Agapanthus

  • USDA zones: 8-10

  • Sunset zones: 4-9, 12-24

American Arborvitae

  • USDA zones: 3-7

  • Sunset zones: 1-9, 15-17

Sadly the hardiness zones are not much of a help for us High Desert folks. The hardiness zones cause more confusion than competence. This requires a higher understanding of our plants to have success in growing plants that are more than capable of growing here.

Fundamentals of Bonsai: Fall

Fall is an important time in bonsai. This is where we direct our trees to do as we please. Fertilization, future cold hardiness, and girth in branches and trunks all come during this time.

Vascular Growth

Vascular growth is what the tree focuses on in the Fall. This means that producing leaves is not the priority since we aren’t going to be photosynthesizing much in Winter. All energy accumulated from the photosynthetic process go to storage in the trees cells. This energy accumulation is what drives the Spring flush of growth. Different species store their energy in different places. Pines are typically in the roots, Junipers are in the foliage, and Deciduous trees are evenly spread in the roots, trunk, and branches.

Cold Hardiness

There is also an important nugget of information about cold hardiness. In bonsai we love the highly ramified branches. In order to get those twiggy branches we reduce the cold hardiness of that branch. The more sugars and starches we have inside the branch of a tree, the lower the freezing temperature is. Therefore, highly ramified branches are highly susceptible to cold damage even though the tree as a whole might be able to withstand a much colder temperature.

Energy Management

Energy management is of supreme importance in the Fall. The more you fertilize the more energy the tree stores. When a tree has a lot of energy it produces long internodes, large leaves, and coarse thick branching. When a tree has a small amount of energy it produces short internodes, smaller leaves, and fine twiggy branching.

This is why following blanket statements about fertilization can be so dangerous. If you just fertilize every 4 weeks with a full dose every year, you’re never going to be creating a tree with highly ramified branching and small leaves.

Wire Bite

If your tree is wired, this season must be a watchful one for you. Wire bite on the branching of trees most commonly happens in the Fall due to the trees focus on vascular growth. Checking the branches frequently allows you to stay ahead of the trees growth and remove wires before it damages the branch.

Fundamentals of Bonsai – Spring

Spring is when the tree wakes up from its dormancy in Winter. The daylight length and temperatures increase and this signals to the tree that it is time to wake up. The tree then begins a cycle that it follows through Spring.

Juniper Chinensis Bonsai Shohin

  • Buds begin to swell

  • Leaves emerge and the tree goes into an energy deficit.

  • The first flush of growth hardens off and tree goes into energy positive

The perfect time to repot is while the buds are swelling. While the timing cannot always be perfectly right before the buds break, the closer to bud break (without repotting AFTER the bud break) the better.

When leaves emerge the tree spends some of the saved up energy from Fall to produce foliage with the possibility to generate more sugars and starches. When this happens the energy “bank” so to speak, goes negative. The new leaves are like an investment. Until those leaves harden off and form a cuticle, they do not photosynthesize. Until this happens this investment is a negative overall.

Pruning too much at the wrong time, defoliating, a hard freeze that kills foliage, pest issues that grow out of control, and even missing a day or two of watering can do a significant amount of damage to your tree’s health. While it doesn’t always end in a dead tree immediately, you need to consider this in the long term. You might have a hard freeze one year, prune a little off at the wrong time each season, defoliate in the Summer, and then after a few years you find your tree dead for what appears to be no specific reason.

Cotoneaster Repot Bonsai

This guy died from a late freeze after the first push of growth. I had recently repotted it and it was weak due to that. It never made it out 😦

A better way to understand this is to think of investing a significant portion of your savings into a stock hoping for a consistent return of maybe 7%. Instead of return, your stock plummets and becomes worthless. To be able to do anything with your money you’re going to need an amount of time to recoup the money you lost. If you continue as if you hadn’t lost all of your money in the investment and then spend with the intention to withdraw your invested money, you’ll be negative because you don’t actually have that money. If you have a tree that loses leaves from a freeze and then pushes out new leaves, the tree will have less energy in the bank. If you proceed by delofiating it to get a smaller push of leaves, you’ll find that it doesn’t have enough energy and will possibly die.

The vigor of the growth, length of internodes, size of leaves, and amount of leaves all depends on what you’ve previously done.

Fertilizing frequency and strength play a large part in Spring growth. If you’ve been fertilizing heavily and at the maximum frequency, you’re bound to have a large amount of energy. This will result in a lot of leaves, larger leaves, and longer internodes. The pot size also has an effect. If you fertilize lightly and infrequently, but you have your tree in a large training pot, you will not see small internodes or small leaves. Restricting the area for the roots to grow creates less vigorous growth.

If you’ve repotted a deciduous tree and pruned a large amount of roots, you’ll only see the amount of leaves that the roots can support. For a photo of this see this blog post about the difference.

Let’s go over what we’ve learned:

  • Daylight length and temperature determine when a tree breaks dormancy

  • Fertilizing strength and frequency (are not the only factors, but major factors) correlate with internode length, leaf size, and leaf quantity.

  • A deciduous tree will only push out growth that it can support with its root system.

  • Fertilizing can be throttled with frequency and strength.

  • Energy for Spring growth is stored by the tree in Fall

  • Repotting is best done before the buds break at the beginning of Spring.

  • New leaves take energy to produce and then produce energy when they harden off.

  • Common bonsai techniques (repotting, pruning, defoliation, watering, etc.) performed at the wrong time or late freezes can damage your tree’s health.

Japanese Maple Leaves

Fundamentals of Bonsai – Basic Physiology

There is a lot of confusion when you begin the bonsai journey. You’ll hear suggestions from everyone about how to do everything. One thing that helps is understanding why you’re doing something. Understanding the physiology of your plants will help dramatically with that.

I wanted to start with this photo that has a bit of information. You don’t have to memorize this to practice bonsai by any means, but I’ll go over the important parts.

Plant Physiology

Koning, Ross E. 1994. Plant Basics. Plant Physiology Information Website. http://plantphys.info/plant_physiology/plantbasics1.shtml. (6-2-2018)

Trees need 4 things to survive:

  • Water

  • Sunlight

  • Air

  • Nutrients

The Leaf

Leaves are responsible for the sunlight and movement of water. Leaves photosynthesize and send the sugars and starches created to the plant via the phloem. As water evaporates in the leaves the process of transpiration occurs. Transpiration in essence “pulls” a chain of water molecules from the roots up to the leaf to replace the loss of water. The cuticle is a waxy covering on the leaf that stops moisture loss once the leaf has fully “developed.” Once a leaf has its cuticle it begins photosynthesizing and accumulating energy. This happens once a leaf has reached its mature size after breaking out of the bud, changed to a darker color, and has become less flexible.

There are several techniques used in bonsai that involve leaves, namely: full and partial defoliation, leaf cutting, pruning, watering, development of branches and trunk, and allocation of resources throughout the tree.

Branches are like roads, the more they are used the bigger they get. If one branch has 20 leaves and another has 5, the branch with 20 leaves will thicken quicker than the branch with 5 leaves. This is because more energy is being created and more water is being moved there from the water loss of the leaves. We learn from this that foliar mass = girth.

The Roots

Roots are responsible for the uptake of water, oxygen and nutrients. There needs to be a balance of water and oxygen in the soil for this to take place and not starve the plant for either water or oxygen. Roots move water and nutrients to the plant through the xylem.

Large roots help to anchor trees in nature. Small fine roots are the main roots that absorb moisture and nutrients. Roots function the same way branches do in the sense that the more fine roots you have attached to a larger root, the bigger it will get.

In bonsai we repot anywhere from every year to every 10 years depending on the needs of the tree. We prune the roots and style them much like we do to the branches above the soil line.

The Stem

The trunk and branches have bark which aids in retaining moisture. I’ll talk more about the stem as needed in further discussions, but what you need to know is: the xylem moves water and nutrients from roots to leaves, phloem moves energy to the tree from the leaves, and cambium helps the tree get thicker and indicates the tree is still living by showing a green tissue layer under the bark.

Wiring and bending a tree can be more difficult depending on the species of the tree. Different species have varying abilities to bend, and this is due to the changes in the xylem, phloem, cambium, amount of water moved (water loss due to transpiration), and bark.

Deciduous Root Pruning Effects

During the early Spring I purchased two cotoneasters from the discount rack at Lowe’s. I took one of them and repotted it and slip potted the other one into a larger container. You can see these photos and notice that the cotoneaster on the right has significantly more foliage than the root pruned cotoneaster on the left.

 

 

 

 

 

 

 

 

 

This is how deciduous trees respond when root pruned. They will not put out more foliage than they can support with the root system and stored up energy from the previous Fall.