TechNotes Tips - Plants, Trees & Flowers Archive

Pruning is a practice that can result in fuller looking plants. Ornamental plants not grown for showy flowers can be pruned during late winter, spring or summer. Avoid pruning during fall and early winter since this may predispose branches or new growth to winter damage.

Pruning of many woody ornamentals is done according to their date of flowering. A majority of spring flowering plants like forsythia and dogwood are normally pruned after bloom. Summer-flowering plants are generally pruned during the winter when they are dormant. Plants not grown for flowering are also best pruned during the winter.

During late fall older needles of white pine often turn yellow, die, and drop to the ground. This is a normal process in the life of this tree. No control measures are recommended. 

Mums should have their dead flowers removed after blooming. After several hard freezes, the foliage should be cut back to the ground. The plants can be protected by covering them with 6 inches of mulch.

Spring-blooming bulbs used in the Midwest and Northeastern U.S. can be planted in late September. The most popular bulbs planted include daffodil, hyacinth, lilies and tulips. Bulbs planted in mass will have the strongest visual impact on the landscape.

Iron deficiency symptoms are obvious in many landscape plants during late summer/early fall. The leaves appear yellowish.

Ash trees were already shedding their leaves in August 2000. When ash trees begin to drop leaves early in the season, it causes concern among homeowners. These ashes are dropping leaves in response to an inadequate root system to support top growth. This dropping of the leaves is usually in response to the root system not taking up enough water or enough nutrients to support the top growth. Although the dropping of the leaves is not detrimental to the tree, next year the dropping could become more severe. If nutrient uptake appears to be the problem (oftentimes leaves show iron chlorosis), fertilize with tree stakes or dig holes around the tree and place fertilizer in the small augured holes.

Dead heading is the removal of old and faded blossoms from flowering annuals or perennials. The removal of faded blossoms will help encourage more blooms by preventing seed pods from competing for the plant's food supply. Oftentimes the old blooms can be pinched off with your hands. Plants that benefit from dead heading include, daylilies, petunias, impatiens, zinnias and marigolds.

Trees need a deep thorough water soaking during the growing season. If adequate moisture is not provided through timely rains, a deep thorough irrigation is needed weekly. When irrigating trees, be thorough and allow for deep penetration. This usually requires using a low flow rate onto the area below the tree but providing water for a long time. Removal of turf or vegetation around the tree may be desirable to reduce the competition for water.

Tree Irrigation during the summer is always a hot topic. A guide for young tree irrigation is shown below (from Texas Agricultural Extension Service):

Appearance of Galls on maples this spring are probably caused by small mites called eriophyids. The maple bladder galls found on silver and red maples and the spindle galls found on sugar and black maple are caused by these mites. Eriophyids when full grown are no more than 1/50 to 1/100th of an inch long. The galls form when the overwintering adults emerge from the buds and move to the lower surface of the leaf blade. The mites irritate the leaf cells resulting in a hollow cavity that forms on the upper surface (galls). The mite then moves into the cavity and produces a new generation. Galls are generally insignificant to the tree’s health.

Magnolias are widely planted in landscapes throughout the southern U.S. There are 80 species, however the three major species are Southern magnolia (M. grandiflora), star magnolia (M. stellata) and sweetbay magnolia (M. virginiana). Magnolias are used as specimens, screens, hedges, border accents and, in some cases, container plants.

The ideal soil for magnolias contains organic matter, is well drained and acidic (pH 5.0 to 6.5). Most tolerate drought, and some species tolerate wet soils. Magnolias should be planted in full sun or partial shade.

Pests of magnolias are not considered to be a major problem. Various types of scales seem to be the major pest problem. However, magnolias can become infected with leaf spots, blights, scabs and cankers (caused by various fungi and bacteria).

Girdling can be a problem with magnolias. Cutting or removing any circling roots close to the trunk is advised. The root system of magnolias tends to spread wider than most trees. For this reason, transplanting magnolias is risky. In general, plant container-grown trees for best results.

Determining a tree's growth rate is done by measuring the distance between bud scale scars. The ring of scars near the branch tip shows where growth started last spring. By locating bud scars for the past years, the rate of growth can be determined over time.

Forsythia is one of the most common shrubs found in landscapes. It produces a yellow flower in the spring immediately proceeding leaf appearance. Forsythias are adapted to well-drained soils and transplant well. Spring flowering of forsythias is associated with preemergent herbicide applications for crabgrass control.

Azaleas and rhododendrons are commonly used shrubs in landscapes. From a taxonomic point of view, all azaleas and rhododendrons are classified in the rhododendron genus. Azalea is commonly used for native deciduous species. Rhododendron often refers to species with large, evergreen, leathery leaves.

Suggestions for planting rhododendrons include:

• Plant on a site sloping north or east to protect them from drying winds from the south or west.
• Plant rhododendrons where they will have wind protection.
• Many people think of azaleas and rhododendrons as shade lovers, yet dense shade can cause decline. Filtered sunlight is best but morning sun with afternoon shade is satisfactory.
• Plant in well-drained soils or areas.

Desiccation is a severe problem on evergreens. This problem occurs when water is leaving the plant faster than it can take it up. Often the conditions favorable for desiccation are sunny mild weather with strong winds in combination with a cold or frozen soil. Symptons appear as burned or discolored needles or leaves. Damage is worse on the side of the evergreen that faces the wind.

With the arrival of summer, keeping newly planted trees alive and healthy becomes a concern for many homeowners. The following suggestions will increase the possibility of survival:
1.) A deep watering of your tree or trees is needed weekly. If rainfall is not adequate, watering with a hose is needed. A slow trickle of water for an hour or so over the whole root area is recommended. A light watering or spraying of the tree leaves is not a proper watering technique.
2.) Minimize traffic, either vehicle or excessive foot traffic, over the root area. A well-structured soil provides air and water required for tree root growth. Excessive traffic on the ground where the tree roots are results in soil compaction, reducing air space in the soil.
3.) The rope ties that connect the tree stakes to the tree can be removed after one year. Leaving the tree stakes provides some protection from lawn mowers.
4.) Be careful not to scrape or cut the bark from the tree when mowing or using weedeaters. Wounds caused by mowing or weedeating can result in port of entries for pests.
5.) A 2 to 3-inch mulch over the planted site will eliminate the need to mow close to the tree and also help prevent weeds and lawn grasses from encroaching. Weeds and turf compete with a tree for moisture and nutrient uptake.

Newly planted trees are especially susceptible to bark splitting during the winter. Splitting can occur when a portion of the tree trunk is warmed from the sun then cools during the evening. Bark splitting can be prevented by wrapping the trunk with burlap strips, commercial tree wrap, or painting the trunk white. These preventative measures reflect sunlight and reduce heat buildup during the day

September is the time to plant spring-blooming bulbs in the Midwest and Northeastern U.S. The types of bulbs that can be planted include daffodil, hyacinth, lilies and tulip. Bulbs planted in mass will provide the strongest impact in the landscape.

Newly planted ornamentals and trees should be watered thoroughly. This is best accomplished through soaking the soil around the plant through trickle irrigation.

Newly planted herbaceous and woody plants need to be watered deeply and frequently during the current stressful weather pattern. Watering new plantings is best done by slowly trickling water from the hose to the base of the plant (or using a soaking hose). This slow wetting allows for a better soaking of the soil around the plant. Watering with higher volumes causes runoff and a less efficient watering. Although it is possible to over water plant material, under very dry weather conditions, the chances of over watering are considerably less than those of under watering.

Norway, red, and sugar maples can exhibit symptoms of leaf scorch, foliar browning, leaf drop and poor annual twig growth. There are multiple causes for these symptoms. Primary causes include trees growing in compacted soil conditions, trunk injury, environmental stress and girdling roots. During heat and drought, symptoms are most likely to be expressed.

Leaf scorch symptoms appear as a drying up or browning of the leaf margins. Scorch appears after periods of unfavorable weather conditions such as drought, high temperatures or hot windy conditions.

The poinsettia is a plant native to Mexico. It was first noticed by Joel Roberts Poinsett, the first U.S. Ambassador to Mexico (1825-1829), near Taxco, a town south of Mexico City. Impressed with its brilliant red color, he sent some of the plants home to his plantation in Greenville, South Carolina. Poinsett then distributed the plant to his many horticultural friends. A German taxonomist gave it the name Euphorbia puicherrima, but its common name, poinsettia, remains the accepted and popular name. The poinsettia has evolved into a symbol of Christmas. With sales of more than 52 million plants each Christmas, it ranks number one nationally in sales for all flowering potted plants.

Poinsettias are adapted to bright sunny conditions. During the holidays, when possible, place the plants in the sunniest exposure in your home. This is usually near a window. Be careful not to let the bracts touch the cold windowpanes, since freezing temperatures can cause damage. Ideally, daytime temperatures should be in the 70-72 F range while nighttime temperatures should not fall below 65 F. Poinsettias, when initially established and grown in commercial greenhouses, were maintained under relatively high humidity. Thus, avoid areas where dry air originates such as ventilating ducts, and fireplaces. Placing a bowl or saucer filled with water near the plant will add humidity around the plant. When buying a poinsettia, avoid plants with flowers. Source: html extension circular, University of Nevada, Linn Mills.