Horticultural Update is published by Extension Horticulture, Texas Agricultural Extension Service, The Texas A&M University System, College Station, TX. Editor: Edna Smith, Designer: Jill Stavenhagen. Contributing Editors: Drs. Samuel D. Cotner, Vegetables; George F. McEachern, Pecans & Grapes; William C. Welch, Landscape; Douglas F. Welsh, Landscape
Editor November / December 1997: William C. Welch, Landscape Horticulturist
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In this issue . . .
Plant of the Month . . . Ilex decidua - Possum-haw Holly
Reflections on Native Pecans
Managing Perennials
Greenhouse Growers Conference
Christmas Gifts for Gardeners
How to Preserve Gourds
Hardy Hollies
Landscape Design Study Course III
Does it Have to Freeze to Have a Frost?
It's a Great Time to Have Your Soil Tested
Garden Checklist
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PLANT OF THE MONTH FOR NOVEMBER / DECEMBER . . . ILEX DECIDUA - POSSUM-HAW HOLLY
By Dr. William C. Welch, Landscape Horticulturist
Texas A&M University, College Station, Texas
Each year in November and December, there is a flurry of interest by consumers, customers, and gardeners in what they call the 'yaupon-like plant without any leaves'. Ilex decidua attracts so much attention because of its spectacular and unique presentation of red, orange, and yellow fruit, which appear when the foliage drops in November or early December. The colorful berries usually remain all winter unless they are removed by the cedar waxwing or one of the other nine species known to feed on the fruit.
Possum-haw hollies are useful in the landscape as large shrubs or small trees, and may occur with single or multiple trunks. Female plants are preferred, since male selections are fruitless and provide little ornamental value.
Culture is easy. Possum-haws are native from East Texas to western regions of the state, and grow in a wide variety of soil and moisture conditions. They tolerate poor drainage quite well, but will thrive under fairly dry situations.
Availability is getting better, but expect some difficulty in locating nursery-grown plants. Some nurseries are now growing female selections from cuttings, which assures the fruit color and sex of the plant. Seeds are easily propagated, but this often results in a high percentage of male plants. Determining their gender is not practical until plants are old enough to flower, which may be in 2 to 4 years. If collecting specimens from their native habitat, two things should be kept in mind. First, select a plant with at least a few berries; second, unless you have access to large-scale digging equipment, choose a small plant. Possum-haws grow quickly once established; however, large collected plants can be slow to recover from transplanting. Ilex decidua is a beautiful and potentially useful small tree adapted to most of Texas. Increasing availability should make it a popular choice for many home owners.
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REFLECTIONS ON NATIVE PECANS
By Larry A. Stein, Extension Horticulturist
Texas Agricultural Extension Service, Uvalde
The pecan industry is one of the most fascinating and intriguing horticultural enterprises in these great United States. We in Texas like to call our state the home of the pecan, yet pecans are native to other parts of North America as well. We know the pecan has been around for a long time, and know it was significant in the diet of the Indians. Yet, the pecan industry as a whole is relatively young.
Sometimes it is amazing to look back and see how far we have come technologically over the last century. My grandmother, for example, has gone from riding a horse-and-buggy to church on Sunday to watching a man land on the moon. The pecan industry, too, has made great strides, especially from a mechanical and labor standpoint. Today, we have unbelievable mechanization, and a mere few seconds are required to bring a pecan crop down to the ground. However, we, as native-pecan land owners, continue to neglect this vast resource.
Through the years, myths and misconceptions have been handed down about pecan production. The first began with the Indians themselves, as they noted the alternate-year bearing tendency of the trees. Many times in the past, heavy crop years were due to overflows, i.e., rivers depositing alluvial silt, rich in fertilizing elements, over the pecan bottom. As a result, trees would make good growth and produce a bumper crop the following year. Over the years, many rivers and streams have been dammed up to prevent such overflows. In the process, many thousands of acres of pecan bottomland have been lost. Sometimes it seems almost inhumane to destroy such a beautiful resource which took so long to develop. Still, with the lack of overflows, trees have had slower growth, and production has diminished. We must now supply nutrients artificially by applying fertilizers to replace the overflow silt.
This corresponds significantly to another problem in native pecan production: management. Too many people have the notion that since 'granddaddy never did anything to his trees and he always had pecans', the same holds true today. But we must remember that things are not like they were back then, i.e., river overflows, etc. Today, growing native pecans involves a total management concept, providing (1) proper spacing and sunlight penetration, (2) fertilization, (3) brush and weed control, (4) pest control, and (5) irrigation.
The first step in providing proper spacing and sunlight penetration is to remove all foreign timber, such as hackberry, mesquite, oak, etc., from the pecan bottom. Once this has been done, some pecan trees must be removed as well, to increase sunlight penetration into the grove. Weak, dying trees, crooked trees, etc., should be removed first. All parts of the remaining pecan trees must receive good sunlight or many of the limbs will shade out, and the only potential for pecans will be on the top.
Trees must also be evaluated for production capability and pecan quality. To do this, we must first get the trees growing and bearing pecans. Thus, our next step would be to apply heavy applications of nitrogen fertilizer to stimulate growth. It may take the trees 3 to 5 years to respond, so we must be patient. Once this step has been taken, some type of weed control should be instigated, generally a combination of grazing and occasional shredding. The next step would be to protect the crop that we have worked 3 to 5 years to set with a pest management program. Finally, we should irrigate the trees at least every three weeks.
The potential to produce native pecans every year is there if we are willing to work. Remember that thinning is a continual process, since the trees continue to grow. Also remember that native pecan management is a sequential, step-by-step process. The pecan grower must evaluate his particular economic situation to see which management steps he can afford to take. If only a couple of steps can be implemented, then he should start at the top of the list and work down.
Even though things are not like they used to be in the pecan industry, the potential across this great state for native pecan production is tremendous. In many cases, land owners will be in better shape if they bring their natives into production rather than attempt to establish a planted pecan orchard.
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MANAGING PERENNIALS IN THE HOME LANDSCAPE
By Dr. William C. Welch, Landscape Horticulturist
Texas A&M University, College Station, Texas
Staking, Pruning, Dead-heading and Pinching. The amount of time and effort necessary to keep perennials at their best varies with the seasons, but keeping a fairly close watch on the plantings can prevent major problems. Tasks likely to need attending to include staking, pruning, dead-heading, and pinching.
Staking. Many newer cultivars of perennials are more compact, and may not require the support of stakes. Some, however, will need these structures if they are not to flop over into adjoining plants and spoil the effect of your design. An important fact to remember about staking is that once the plant shows a need for stakes, it is actually too late to provide them effectively. By providing support early in the growing season, the structures are less conspicuous, and the total effect much more natural in appearance. Our ancestors often used twiggy brush or stakes cut from nearby woods to support the tall-growing or vining plants they grew in their gardens. This is still a practical way to stake some plants, although most gardeners prefer to use specially-constructed wire rings or bamboo stakes. Another option is the steel stake coated with green plastic; this is generally available and blends well into the natural environment. Bamboo stakes, arranged in a circle or triangle and encircled with twine or jute string, work especially effectively in providing support for large clumps. To fasten plants to any of these supports, use plastic-covered wire ties.
Pruning. Our long growing season makes pinching and pruning advisable for many species of perennials. Some plants, such as most of the salvias, are much more attractive if given an occasional clipping during the warm summer months. Light applications of fertilizer and thorough watering after pruning or pinching help plants recover quickly and return to flowering.
Dead-heading. Dead-heading involves the removal of spent flowers and stems, both to keep plants in an attractive condition and to prolong their season of bloom. If this maintenance is neglected, many species of perennials stop producing flowers and, instead, redirect their energy to the production of seed. Often, too, the spent flowers are unsightly. The petals of some species drop away neatly as the flowers fade. But those of many other perennials will hang on as they wither, unless the whole flower is removed. Dead-heading doesn't improve all plants, however. Some perennials produce a dividend of colorful fruit and seeds after they flower. In these cases, removing the spent flowers will cheat the garden of an added season of interest. Developing a familiarity with the habits of your plants as you choose them is the best guide in this matter. Some perennials, such as many perennial salvias, can be pruned or sheared after each flush of flowers during the growing season, to maintain a tidy appearance and encourage additional flowering.
At the end of their flowering season, most perennials should be cut back severely. This not only will invigorate the plant, but it will provide a much tidier appearance in the garden. Most bulbs are an exception to this rule. Spring-flowering narcissus and leucojum, for example, should be allowed to mature their foliage before removing it. This usually occurs 4 to 6 weeks after blooming. Dying foliage is not a visual asset to the garden, but is necessary in order for the bulbs to store enough energy for the next year's flowers. Companion planting with annuals can help conceal this maturing foliage while adding color to the garden. Pansies, for example, are often inter-planted with spring-flowering bulbs for this purpose.
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TEXAS AND SOUTHWEST GREENHOUSE GROWERS CONFERENCE - November 11 - 13, 1997. Hilton Hotel and Convention Center, College Station, Texas. For information, call (409) 845-7341.
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CHRISTMAS GIFTS FOR GARDENERS
By Dr. William C. Welch, Landscape Horticulturist
Texas A&M University, College Station, Texas
With the arrival of December, the minds and thoughts of even the most avid gardener turn away from the yard and garden toward Christmas and the holiday season. Gardening chores are temporarily laid aside as the sights and sounds of Christmas fill the air.
If you have gardening friends on your gift list this year, consider surprising them with a 'green thumb' type of gift, which can be used and enjoyed year-round as they pursue their favorite hobby. Garden items make unusual, welcome, and unique gifts, and the selections are vast. There is something for nearly everyone in any price range. The following gift suggestions may just fit into your gardener's stocking this Christmas.
Garden Tools. From a hand trowel to a riding lawn mower, gardening tools are guaranteed to please. Consider one of the many time- and work-saving electric lawn or garden products. There are many from which to choose.
Garden Accessories. Many unique and interesting objects fall into the garden accessory group. Sculpture for the patio or garden can last for years. Or, you may choose to be more casual, with wind chimes, a bird feeder, flower pots, or hanging baskets.
Gardening Books and Magazines. Although the selection of gardening books is wide, choose a book that is adaptable to the recipient's interest. One of the popular monthly gardening magazines will be appreciated throughout the year.
Garden Plants. Although seldom considered, outdoor plants can make welcome gifts. The Christmas season is ideal for planting all major trees and shrubs. You might want to consider a pecan or fruit tree for your gardening friend. Select one which will complement the recipient's landscape. Regardless of the choice, plants make a delightful and lasting gift.
A Gift Certificate. If all else fails, why not consider slipping a gift certificate into the stocking of the 'green thumber'? Your local nursery or garden center will be most happy to fulfill your wishes here.
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HOW TO PRESERVE GOURDS
By Dr. William C. Welch, Landscape Horticulturist
Texas A&M University, College Station, Texas
The gourd is a fruit that is highly decorative, and it will last for years if properly cured. The curing process usually takes about 3 weeks.
Harvest gourds when they stop increasing in size and start drying, and the leaves begin to mottle and turn brown. Cut the gourd loose from the vine with a sharp knife or pruning shears, leaving a stem 1 to 2 inches long. Wash the gourds in warm soapy water, and rinse in clean water containing a little household disinfectant. This will remove any soilborne bacteria clinging to the shell that might cause discoloration or rot. Dry each gourd with a soft cloth to avoid bruising or scratching the skin.
The next process -- surface drying -- takes about a week; its purpose is to dry and harden the outer skin and set the color. Many gourds have beautiful colors and markings which may fade or become discolored if not preserved. A good way to handle small gourds is to string them like beads through the stem, and hang to dry. Take care they do not touch. If gourds are too heavy to suspend on a string, they should be laid on a floor or table, on several thicknesses of newspaper, in a room that is warm and dry, with good air circulation. Turn the gourds daily, and replace any newspapers made damp by the curing gourds. Those that begin to shrivel or develop soft spots should be discarded; they are immature and will never cure properly, and they may develop molds which will spread to the others. After about a week, the surface of the gourds should be well dried and the colors set.
The next process is internal or final drying in darkness, to prevent fading of the color. This takes 2 to 3 weeks. Lay out the gourds as before, in a warm dry place with good air circulation as well as darkness. Heat encourages rapid drying, and darkness holds the color. Dryness also discourages molds and mildew.
Gourds may be displayed in their natural state, but often they can be greatly improved by decorating. One way to enhance the natural beauty of gourds is to wash and buff them with a soft cloth to produce a soft shiny surface with highlights. Or, coat the surface with liquid plastic to give a hard glossy finish. Gourds with a poor, dull color can be painted. Suspend them by the stem or place on the rim of an empty can while brushing or spraying with paint.
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HARDY HOLLIES
By Ted Fisher, Travis County Horticulturist
Texas Agricultural Extension Service
The hollies are landscape heroes. They survive devastating freezes and stand the test of drought and heat. What more could one ask? If you do not have a generous assortment of hollies in your landscape, think again, and plan to add a few this winter. They are hard to beat.
An entire landscape of hollies really would not be boring. For one thing, you can get any shape or size plant you need. Some grow quite large, while other types stay small and low. Most hollies are evergreen, but a few shed leaves in the fall. Individual holly leaves may be spiny or spineless.
Hollies grow in many types of soils, but they do best in neutral to slightly acid well-drained loam. When planting, you should consider incorporating sand and organic matter into the planting bed. It may be necessary to add iron compounds to the soil periodically to prevent or correct iron deficiency in alkaline soils.
Many types of hollies are available for today's landscape. One of the unusual things about these plants is that they are named after countries. Classes of hollies are American, English, Chinese, and Japanese.
Japanese hollies are those used extensively in landscape plantings. They produce relatively small, spineless leaves and black berries. They range from dwarf, slow-growing plants to relatively fast-growing, medium-sized shrubs. Let's look closer at them.
Heller holly is one of the smallest of the dwarf types of Japanese hollies. Its growing habits are compact, and leaves are small. With age, the plant develops a rounded, spreading shape. Ten-year-old plants are usually no more than 3 to 4 feet high and 5 feet wide. Little or no pruning is necessary.
Round-leaf holly was the first Japanese holly to become popular. Compared with other hollies, its leaves are large and flat. It does not produce berries. Some gardeners call it a box-leaf holly. One of the larger-growing hollies, it may reach 8 feet if not pruned.
Convex-leaf holly is known as the bullata holly. It is noted for its small, convex, or cup-shaped leaves. Black berries are usually produced in abundance.
Herz holly is gaining in popularity. It is similar to both the round-leaf and convex-leaf varieties. Leaves are relatively large and have a slight cupped shape. Growth is vigorous and leaf color is dark green.
Burford holly produces glossy, dark green foliage. Generally, only one leaf spine is present, and this is at the tip of the leaf. This very popular and widely-used landscape holly produces an excellent crop of berries each year. Burford grows quite large, often reaching 10 to 15 feet.
Dwarf Burford holly has characteristics similar to Burford holly. The glossy, dark green leaves are smaller, and growth rate is slower. The leaves, generally, have only one spine at the tip. Dwarf Burford will grow to a height of at least 5 to 6 feet if not pruned heavily.
Rotunda Chinese holly is one of the most satisfactory shrubs available. This variety is quite different from other Chinese hollies in that it has a dwarf habit of growth and a rounded shape. An important advantage is that little or no pruning is required to produce a compact plant. 'Rotunda' will tolerate hot, dry locations that would injure other shrubs.
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LANDSCAPE DESIGN STUDY COURSE III - January 26-28, 1998. College Station, Texas. Attendance is increasing with each of these landscape design programs. Many Master Gardeners are attending and are most welcome. Contact the Extension Horticulture office for registration forms (409) 845-7341.
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DOES IT HAVE TO FREEZE TO HAVE A FROST?
By Calvin G. Lyons, Retired Extension Horticulturist
Texas Agricultural Extension Service
We are currently hearing about frost and freezes, and with the upcoming winter and spring, it is always good to understand exactly what we are talking about. Both of these phenomena deal with plant-killing temperatures. It is important to understand that where you see ice, the temperature at that point is 32 degrees F or below.
The weather bureau takes all official readings inside a shelter at a 5-foot height. Generally, the overall air temperature during a frost is above freezing, but because the earth's heat dissipates into the atmosphere during the night, it keeps getting colder and colder near the soil's surface. At times like this, it could be 40 degrees F at 30 feet above ground and 25 degrees F at ground level. These 'inversions' usually occur only on clear calm nights. Since cold air is heavier than warm air, unimpeded cold air will slowly move downhill like water. Low-lying locations are referred to as 'cold pockets'.
Freezes, on the other hand, are generally characterized by massive movements of below-freezing air from the north. Such arctic blasts usually have strong winds associated with them, making air temperatures the same, regardless of height and site. During a freeze, plants have little chance of survival unless they are protected from the winds. Though 'wind chill' itself has little effect on plants, the protection prevents plants from losing heat as fast. The differences between a frost and a freeze become very important when we are talking plant protection. Since it is not as cold as long during a frost period, usually something simple, such as covering the plants, works very well, but during a 2- or 3-day Siberian Express, the addition of heat becomes necessary for plant survival.
Really, the proper saying should be, "It does not have to freeze at 5 feet inside a shelter to have frost," rather than "It does not have to freeze to have a frost," because the latter is really incorrect.
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IT'S A GREAT TIME TO HAVE YOUR SOIL TESTED
By Sam Cotner, Head
Department of Horticultural Sciences
Texas A&M University
If your garden performed below expectations last year, or maybe things just didn't grow quite right, a few dollars invested in a soil test may be just the solution. A properly prepared and fertilized garden soil is the real key to successful gardening in most areas of Texas. You can't look at the soil, taste it, smell it, or feel it to tell whether your soil is low in nitrogen, high in phosphates, or maybe just right. One sure way to overcome the mystery, and avoid confusion when it comes time to purchase fertilizers, is to have your garden soil tested.
Why is it important to know how much phosphorus or nitrogen is in the soil, or what the pH of the soil is? The answer is simple. Vegetables don't do well in improperly fertilized soil, whether it be too fertile or not fertile enough.
The soil test report will tell you the level of nitrogen, phosphorus, potassium, calcium, and magnesium available to your garden plants. It will also indicate the pH (acidity or alkalinity) of your garden soil. For the most part, this is all you need to know to properly fertilize your garden soil, and insure a bountiful harvest.
To take a soil sample, make a hole about a foot deep in the garden with a spade or sharpshooter. Throw out the first spadefull of soil. Then, from the back of the hole, cut a slice of the soil 1/2 inch to 1 inch thick. Be sure the slice is at least 6 to 7 inches in depth, with fairly even width and thickness. Then place the soil slice in a bucket or tub. Repeat this procedure 4 to 6 times in different spots in the garden, depending primarily on the size of the garden. Thoroughly mix the composite of the soil, and mail it to the Soils Testing Laboratory here at Texas A&M University. Soil testing is a service provided by the University; soil test kits, with instructions, can also be obtained from your local county Extension agent.
If a soil sample is taken in late winter or very early spring, you should expect to get your results back within 2 to 3 weeks. If you wait until spring, then it may take considerably longer to get your results back. An adequate soil test, properly done and properly interpreted, will go a long way toward insuring a bountiful harvest from this spring's garden.
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GARDEN CHECKLIST FOR NOVEMBER / DECEMBER
Dr. William C. Welch, Landscape Horticulturist
Texas A&M University, College
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