Once the tree is planted, avoid raising the ground level and mounding over the root zone. Mounding up of the root zone is caused by adding too much soil back at the time of planting or even through the years. If the hole is dug too deep and then partially filled before planting, the tree will settle in, causing it to be planted too low. Trees planted too low leads to oxygen deficits in the root zone. If you notice the planting hole has settled, carefully remove enough soil to expose the trunk flair.
Plan and install underground irrigation lines before planting to avoid cutting roots later on. Most of the feeder roots are in the top six inches of soil. Avoid roto-tilling within the root zone as the tree matures.
Match your tree placement with the water requirements of surrounding plants, or place on a separate irrigation zone (hydro-zone it). Water the tree within the tree ring regularly and deeply. Watering is more critical during the first months. Keep the soil evenly moist, but not waterlogged. Test the soil with a soil probe, or monitor the irrigation using the ET rate (evapotranspiration) as a guide.
Tree roots primarily gather water and nutrients within the top 12 inches of soil. Special attention is needed during the first 3 - 5 years. As the tree matures and establishes, supplemental irrigation will be less frequent, but deeper, less frequent irrigation is still the best method. If using a drip line, as the root zone expands with the seasons and years, widen the circle of the drip line to reach the expanding roots.
Soil and Feeding
Forests are few on the plains, however, city landscapes are referred to as urban forests. In addition to area wide drawbacks that prohibit a larger list of regionally relative trees, urban landscapes have the additional drawbacks of air pollution, compacted soil, concrete and asphalt cover over root zones, root injury due to installation of irrigation systems or other construction in established beds, and their inclusion in turf that is often treated with chemical fertilizers, herbicides, fungicides and pesticides. Adding up all these negatives, it is no wonder many trees fail to achieve maturity and a long life. Given these conditions, it is easy to understand the tree's stress, lowering its resistance to disease and insects.
Conditions more conducive to healthy, low maintenance tree growth mimic certain conditions found in forests. Most notably is the absence of turf. But this doesn't preclude undergrowth. Leaves, stems and twigs are left to fall to the forest floor and decay, adding organic matter to the soil, aiding microbial life. This organic mulch cover helps retain moisture and moderate temperature. Soils infused with organic matter and microbial life are balanced with proper proportions of air and water spaces preventing soil compaction. Spaces that provide room for movement of roots, macro and microbial life. A healthy forest ecology prevails both above and below ground. Absent from naturally healthy forest stands are periodic applications of salt-based fertilizers, microbe killing pesticides, fungicides, and herbicides.
The gardener's skill and care is all important in our urban forest, not having the advantages of natural forest communities. For most residential gardeners, trees will be located within turf areas. Incorrect turf maintenance contribute to tree problems. Both turf and trees benefit from soil that is well aerated and amended with organic matter. Soil amended with organic matter twice yearly will have a higher population of beneficial soil life, including mycorrhizal fungi.
The symbiotic relationship between mycorrhizae fungi and roots of plants has been established for quite some time. Trees particularly benefit from mycorrhizae in our urban landscapes. These fungi extend both the reach and surface area of the trees roots, 700 to 1000 times! Mycorrhizal fungi increase the range of roots for absorption of water and nutrients and is able to travel where roots cannot. There are two types of mycorrhizae:
- Ednomycorrhizae, which grow close to the surface of roots and can form webs around them and
- Ectomycorrhizae, which penetrate and grow inside roots as well as extend outward into the soil.
Ectomycorrhizal fungi associate with hardwoods and confers. Endomycorrhizal fungi prefer most vegetables, animals, grasses, shrubs, perennials and softwood trees.
Gardeners should add mycorrhizae when planting trees. Mycorrhizal fungi and other microbiological life are killed with applications of chemical fertilizers, herbicides,
fungicides and miticides. If these chemicals are used, steps must be taken to remediate the soil through aerobically activated compost tea infusions and other microbe stimulants. Organic matter must be added to our organic deficient soils; food for the microbes. (Teaming With Microbes, A Gardeners Guide to the Soil Food Web, by Jeff Lowenfels and Wayne Lewis, Timber Press, 2006.)
Turf planted right up to trees will at first have root dominance of the surrounding area. To give your trees a better start, create a mulch ring from 2 - 8 feet around the trunk, depending on the size of the tree. Avoid using soil amendments and mulch of any plant or animal matter or compost that has been exposed to the class of persistent synthetic chemicals, the pyralids. As the tree grows and the root zone expands and matures, the tree roots claim dominance on water and nutrients. The tree casts more shade and turf thins. Consider ground covers other than turf in shaded areas.
Groundcovers for shade include Aegopodium podagraria variegatum, Bishop's weed, Cerastostigma plumbaginoides, hardy blue plumbago, Mahonia repans, creeping Oregon grape holly, Hedera, English ivy and Vinca major and minor. These are all low water-use groundcovers, once established. Use them separately from each other, they are aggressive and do not combine well in a shady flower bed.
Mahonia repans spreads slowly and will take several years to fill in, but is worth waiting for the plants to mature. Lambs ear, Stachys byzantina and S. byzantina 'Helen Von Stein' grows in dry shade without becoming invasive. Blue mist spirea, Caryopteris, and Nandina varieties are two, low water-use shrubs. Bugleweed, Ajuga reptans, and columbine, Aquilegia spp., grow and flower in part shade.
Pruning refers to cutting a branch, stem or twig on a woody or herbaceous perennial. Pruning is usually performed to remove branches for safety, to prevent disease and decay, for shaping of growth and for increased growth and flowering. Of all the grooming techniques, pruning is the most important grooming technique to learn properly. In herbaceous perennials, bad pruning can be outgrown by the next season. However, bad and incorrect pruning can lead to long term problems, disfigurement and death of trees.
Have a Reason to Prune
Not all trees need to be pruned. In fact few trees need to be pruned just for pruning's sake. Gratuitous pruning should be avoided.
- Pruning is not topping; trees and shrubs should not be topped. Topping is tree (plant) mutilation. (Why Topping Hurts Trees.)
- Do not lion tail trees. (Lion Tailing.)
- limbs become weak and may break
- increased sunlight on the interior of the tree can cause sunscald
- it stimulates vigorous new growth on the inner portion of the tree that is weakly attached and prone to break.
- it removes too much foliage disrupting the trees energy reserve for future growth
- it destroys the tree's appearance and value. (From the National Arborist Association.)
- Prune for safety. Because we may acquire a landscape where every plant was not perfectly placed, pruning may be necessary to prevent branches or twigs from injuring people as they walk through the landscape. Trim branches to avoid having an eye poked, etc. Your landscape needn't be an obstacle course. Trim branches that intrude on walkways, doorways, paths and sitting areas unless creating a jungle environment is your objective.
- Prune out dead, diseased and damaged wood. Dead, diseased and damaged wood is an entry point for pests and pathogens. When properly pruned, trees will compartmentalize the injury and heal themselves. The time to prune these is at the time you notice it, but it is best before the spring growth spurt.
- Do not prune out more than 25% of a trees foliage in any one growing season.
- Rejuvenating or shaping of trees. It is best to hire a certified arborist to properly prune and shape landscape trees. Landscape trees are in investment and asset to your landscape. Certified arborist are educated and trained in the latest correct methods of caring for trees. (Pruning Mature Trees.)
- So far, the Amarillo area has not recorded oak wilt disease. For areas with oak wilt, oak trees should only be pruned in the heat of summer and the cold of winter. Pruning cuts on oak trees should be coated with a pruning paint. (Texas Oak Wilt.) Sanitize pruning tools after cutting on oak trees.
- Avoid injury to your self and others when pruning large branches.
- Use the proper equipment when pruning for your safety and health of the tree.
- Do not use spikes when climbing trees.
- Hire an arborist for difficult pruning jobs, pruning cuts that require climbing a tree or for correcting other problems.
- Pruning near power lines: By Texas law (Health and Safety Code, Chapter 752), only professionals who are authorized by the local utility are allowed to prune or remove trees closer than 10 feet to high voltage power lines.
How to Prune
Proper pruning techniques are essential for the health and appearance of your plant, whether it is an herbaceous perennial, shrub or tree. Again, this does not mean that a gardener should practice indiscriminate pruning - have a reason.
- Pruning cuts should be made just outside the branch bark collar. Be very careful not to cut into the branch bark collar (a ring of compressed bark at the branch crotch). Do not make cuts flush with the trunk or lateral. The International Society of Arboriculture recommends the 3 cut method. To avoid tearing the bark when removing a large heavy limb, first make an undercut 12-18 inches from the branch bark collar. Make a second cut about an inch outward and above the undercut. Now cut the stub back to the branch collar at an inward angle.
- When pruning to reduce size of the tree, take the cut back to the point of origin, or joint. On a large branch removal, cut back to a lateral that is large enough to assume the terminal role, at least one third the diameter of the cut stem. (Proper Pruning Cuts, and USDA Proper Pruning Cuts ).
- Make clean cuts, do not crush the branch or stem. Do not make any stub cuts or flush cuts.
- To avoid transmitting disease, pathogens or insect eggs, wash or sterilize the blades with each cut on trees and shrubs with these problems.
- Wound dressings such as pruning paint are not necessary after pruning. They do not aid in the healing process, and may slow it. This is except in the case of cuts on oak trees in areas affected by oak wilt.
For a healthier, natural look in pruning evergreens that overflow onto walks, paths and doorways, avoid shearing. The best time to start periodic pruning is as soon as you notice the evergreen will be or is overflowing. Use pruning shears to selectively cut out the longest overgrown branches and branch tips, leaving some branches to cover up the cut stems. Always cut back to a joint. Do not make stub cuts. Do not prune the central leader or trunk. Shearing is quick and easy, but destroys the natural shape of the evergreen. Shearing of evergreens will create a dense exterior growth that shades the interior, causing the interior foliage to die. Evergreen shrubs that have been repeatedly sheared are prone to needle browning and are subject to die back from cold winter temperatures and dry wind. You are then left with an ugly, brown, twiggy shell. Needles only grow on the growing tips out and will not grow on interior branches that are needleless. (Pruning Evergreens ).
The upkeep, quality and selection of pruning tools is important too. Keep your pruning tools clean and sharp. To avoid transmitting disease, pathogens or insect eggs, wash or sterilize the blades with each cut on trees and shrubs with these problems. There are two basic types of pruning shears, also called clippers, snippers and secateurs: anvil and bypass pruners.
Anvil shears consist of one sharp blade opposed to a flat piece of softer metal. The sharp edge comes down as a knife on a cutting board. Anvil pruners are better for cutting out dry, hard and dead wood.
Bypass pruners work more like scissors, with two sharp blades sliding past each other. Bypass pruners make clean fresh cuts on green stems, as long as the blades are sharp. The better the quality shear, the more features it'll have, including the capability of sharpening and replacing blades. There are many styles and sizes to fit a variety of hands. These hand held shears should be used for stems or branches up to no more than 3/4 of an inch.
For stems 1/2 to 3/4 inch to 2 inches in diameter, use a lopper. Loppers have thicker blades and longer handles for better leverage in making clean cuts. Loppers come in both the anvil and bypass styles.
Pruning saws are best used for branches 1" in diameter and thicker. Pruning saws come in various sizes, many of them with curved blades.
Pole saws can reach branches up to about 14 feet and cut branches no more than a few inches thick. For pruning cuts higher up than 14 feet, consider calling a certified arborist. They are trained in safety, as well as tree care.
These are just a few tips to help you achieve the long lasting beauty we envision as trees are planted. Following all the seven basic principles of gardening will lead you along a path of successful low maintenance gardening, lined with trees.