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Aug 142012

Under natural forest conditions, the annual decomposition of leaves, needles and twigs provide a fresh resource of minerals for tree and shrub use. Landscape trees grown in lawns and driveways usually do not have this nutrient source and are in need of additional minerals since landscape debris is routinely hauled away.

Sixteen chemical elements are known to be important to a plant’s growth and survival. The first of these are carbon (C), hydrogen (H) and oxygen (O), which plants acquire in sufficient quantities from the air and water. The other 13 mineral nutrients, are acquired by plant roots, which absorb soil minerals dissolved in water. The required mineral nutrients are divided into two groups: macronutrients and micronutrients.

The primary macronutrients are nitrogen (N), phosphorus (P), and potassium (K). These major nutrients are usually lacking from the soil first because plants use large amounts for their growth and survival. The secondary macronutrients are calcium (Ca), magnesium (Mg), and sulfur (S). Fertilization with these nutrients is not always needed.

Micronutrients are nutrients needed needed in only very small quantities . The micronutrients are boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo) and zinc (Zn). Southern Idaho soils can be deficient in S, Fe, Mn, and Zn.

 August 14, 2012
Aug 142012

The type of soil that a tree or shrub grows in can affect its nutrient needs. Soil texture and soil structure influence the amount of water, air, and nutrients held in the soil for plant use. Clay soils can be nutrient rich, but have a large amount of fine particles that tend to compact and restrict water and air movement. Sandy soils drain well, but contain many coarse particles that have little capacity for storing water, air and nutrients. Organic material can be thoroughly mixed into soils with high clay or sand contents to help improve soil structure. Repeated applications may be needed depending on the amount applied and the stage of decomposition or type of organic matter used. Organic material should be mixed into the soil up to several years before trees are installed to obtain maximum benefit.

 August 14, 2012
Aug 142012

No single symptom tells you that trees or shrubs need additional fertilization. Some nutrient deficiency symptoms can be similar to symptoms of cultural problems or diseases. Slow growth rate, small leaves, fewer flowers, smaller fruit, and pale green or yellow (chlorotic) foliage with mottling between the leaf veins may all be signs of nutrient deficiency.

Two methods of determining nutrient deficiencies include:

Soil Testing

Advantages – provides soil pH, levels of K, P, organic matter content and minor nutrients such as iron or zinc.
Disadvantage – does not provide reliable information on N because N is rapidly lost through leaching or removed by plants

Plant Analysis

There are two methods of determining nutrient deficiencies through plant analysis:

Visual symptoms – include length of shoot growth, leaf color, leaf size, and color pattern and timing of leaf drop

Advantages – N and Fe are often the easiest visual symptoms to identify
Disadvantage- symptoms can be deceiving and/or nonspecific

Foliar tissue analysis – provides the concentrations of specific elements in plant foliage (usually leaves)

Advantages – when combined with soil tests it can provide a good picture of nutrient problem(s) – deficiency or toxicity
Disadvantage- nutritional needs for many landscape plants is unknown

 August 14, 2012
Aug 142012

Trees should be fertilized in early spring or mid-fall as long as the soil temperature is above 40º F two inches below the soil surface. Soil should also be moist. Avoid fertilizing in late summer and early fall as a nutrient application at this time could cause unwanted succulent growth that may fail to harden off before fall frosts hit.

Fertilizer Application Methods

Broadcast or topdress – fertilizer is added directly to the soil surface. This method is good for N, which moves readily through the soil, but poor for P and K that move slowly through the soil. Fertilizer should be applied to the drip line and at several foot intervals out from the drip line for mature trees.

Soil incorporated – dry or liquid fertilizer is added to holes in the soil beneath the canopy and extended beyond the drip line and provide a long lasting effect. Holes should be up to 12 inches deep and 1 to 2 inches in diameter and made in concentric circles 2 feet apart around the tree trunk with the first circle no closer than 3 feet from the trunk.

Foliar sprays – best for supply nutrients for plant use in only trace amounts, such as Zn, Mn and Fe.

Tree spikes are a dry soil injection method, with a hardened column or cylinder of fertilizer hammered into the soil.

Controlled release pellets are typically broadcast on the soil surface, but they can also be placed in holes augured into the soil.

Tree spikes and slow release pellets may delay the development of winter hardiness so it is best to use them in late fall or early spring.

 August 14, 2012
Aug 142012

Recommended rates of fertilizer are calculated using the ground area under the tree canopy. The amount of fertilizer to add depends on the fertilizer composition and is usually calculated using the desired N rates. Nitrogen rates range from 0.2 to 0.4 pounds per 100 ft². Excess nitrogen can be detrimental to plant growth.

Quantities of common fertilizers, incorporated into the soil, needed to provide equivalent amounts of N.
Applications rates expressed pounds of fertilizer material per 100 ft² of ground area.
Fertilizer Rate
Fertilizer analysis
0.4 lb N per 100 ft²
0.25 lb N per 100 ft²
20 lbs
12.5 lbs

from 1997 Bulletin CIS 1068. Fertilizing Landscape Trees

Sample Fertilizer Application Problem

If a 10-year-old tree has a canopy that is 20 feet wide, a trunk that is 5 inches in diameter, and roots that extend 35 feet from (one side of) the trunk, how much 18-6-12 fertilizer should be applied via the broadcast method? Use a rate of 3.5 lb. of nitrogen (N)/1000 ft²

First, figure the surface area occupied by the tree’s roots. Area =π*r² where π = 3.14 and r = 35 ft.
= 3.14 x 352
= 3846.5 ft2

Second, calculate the number of pounds of nitrogen needed to cover the root zone.
Pounds of Nitrogen = 3.5 lb. N x 3846.5 ft²
Needed 1000 ft²
= 13.5 lb. N

Third, calculate the number of pounds of fertilizer needed to cover the root zone.
1. Important Relationship
Pounds of Fertilizer x Percent Nutrient = Pounds of Nutrient

2. Calculation for
Pounds of Fertilizer 13.5 lb. N
Needed    = 0.18 N     = 75 lb

 August 14, 2012
Aug 142012

2001 CIS 757 Fertilizer Placement

1997 CIS 1068 Fertilizing Landscape Trees

2004 CIS 1124 Nutrients Plants Require for Growth

2000 CIS 815 Northern Idaho Fertilizer Guide: Blueberries, Raspberries, and Strawberries

1994 PNW 121 Nutrient Disorders in Tree Fruits

1997 CIS 1066 Composting at Home

Other websites that present fertilizing information for trees and shrubs are:

Texas A&M:

Ohio State University

University of Massachusetts
Fertilizing Trees and Shrubs

 August 14, 2012
Aug 132012

Early spring and early fall are the best times of the year to plant because plant shoot growth is minimal and roots have time to become established after planting. Bare root plants should be planted before bud break in March, April or May. Balled and burlapped and container plants can be planted anytime of the year as long as the soil is not frozen. However, early spring or early fall are still considered the best times to install these types of nursery plants.

Where to Plant

Select plants appropriate for the location in which they’ll be planted. Pay attention to the eventual mature height and spread of a tree or shrub, keeping in mind that some community ordinances may restrict planting of trees near power lines, parking strips, street lights, sewers, traffic control signs and signals, sidewalks and property lines.

Other questions to consider are:
  • Will this tree or shrub drop leaves, flowers, or fruit that may be a nuisance to neighbors?
  • Will this plant receive the sufficient amount of sunlight in this location? Will it shade other plants?
  • Will this plant share moisture requirements with the plants surrounding it? Is it compatible?
  • What kind of care, including pruning, will this plant require?

Many of the resources listed here provide information to help homeowners answer these questions.

 August 13, 2012
Aug 132012

Bare root plants should be unpacked carefully and any broken roots should be cleanly pruned off. The roots can be soaked in a bucket of water for up to 4 hours and protected from heat and drying before planting. Do not prune any healthy roots now. Once the hole is dug and the roots spread out, any roots that are too long may be removed at that time to prevent circling or kinking.

Balled and burlapped plants should be handled carefully by the soil ball, not the trunk or branches, to prevent root and trunk damage. Once the plant is in the hole, twine, nails and excess burlap should be removed from the top of the root ball. Synthetic burlap and in-ground fabric bags should be completely removed.

Container plants should be kept in their containers until they are ready to be put in the ground to protect the roots from drying out or getting damaged. Fiber and pulp pots decompose slowly and should be removed completely or sliced before planting to avoid rot and drainage problems. Some plants may be pot bound or have roots that are matted together. To improve root growth into the surrounding soil make 4 to 5 shallow cuts around the root ball and loosen the roots on the sides and bottom of the root ball before planting. For severely pot bound plants, the butterfly method can be used.

 August 13, 2012
Aug 132012

Dig the hole only deep enough to hold the root ball. When planting in loam soil, the root flare on the tree or shrub trunk is planted level with the surrounding soil. If you can’t see the root flare, remove soil or burlap until you do. When planting in clay soil, the root flare is planted 1 to 2 inches higher than the surrounding soil (see diagram). Alternatively, you can form a one-inch pedestal at the bottom of the planting hole for the root ball.

planting depth

The planting hole diameter should be two times the diameter of the root ball. The minimum planting hole diameter can be 12 inches wider than the root system and the maximum can be up to five times the root system diameter. The sides of the planting hole should be vertical. If the sides of the planting hole appear shiny or glazed, rough up the edges with a shovel to loosen the soil before planting.

Before adding soil back into the planting hole, make sure that roots are not kinked or circling. Start adding soil in three to four inch layers lightly firming the soil between layers by lightly stepping on the soil. Backfill soil may be mixed with organic matter at a rate of 3 parts soil to 1 part organic matter to help improve soil texture of medium or fine textured soil. Adding organic matter to the backfill soil is not always recommended, especially in a heavy clay, since sometimes roots will not leave a richly amended hole to grow into the adjacent inferior soil, and circling of roots may occur. Avoid covering the top of the root ball with backfill soil. Make a 2 to 3 inch soil berm around the edge of the planting hole to form a shallow basin. Water the plant in well by filling the basin with water. In heavy clay soils, watch that this berm drains within a couple of hours. Fertilization is not recommended at time of planting. Once the plant is well watered in, apply a layer of mulch 2 to 3 inches thick to the basin, avoiding placing mulch against the base of the trunk.

 August 13, 2012
Aug 132012

Planting Landscape Plants

Landscaping and Utilities: Problems, Prevention, and Plant Selection
Download or order hard copy online

Plant Materials for Landscaping
Download or order hard copy online

Other useful sites on planting trees and shrubs

USDA Plant Hardiness Zone Map
Planting and Maintaining Trees & Shrubs
Proper Application of Mulch Around Trees and Shrubs
Selecting and Planting Trees
Hawthorns In The Landscape, HYG-1051-88
Maples in the Landscape, HYG-1057-88
Sexes In Ornamental Plants, HYG-1059-88
Viburnums In The Landscape, HYG-1062-88
Hydrangeas in the Landscape, HYG-1063-03 
Arborvitae For The Home Landscape, HYG-1077-88
Growing Rhododendrons and Azaleas in Ohio, HYG-1078-01
Mulching Landscape Plants, HYG-1083-96
Deciduous Shrubs for Ohio, HYG-1085-02
Functional Uses of Plants in the Landscape, HYG-1134-94
Deciduous Trees and Shrubs With All-Season Interest, HYG-1143-96
Choosing Landscape Evergreens
Blueberries for Home Landscapes
Planting and Transplanting Trees and Shrubs
Trees are Good” Organization

University of Illinois (Plant selection)

University of Minnesota (Plant selection)

Ohio State University (Plant selection)

Oregon State University (Plant selection)

 August 13, 2012