Lawn and Garden Update has undergone a transformation . . .
Welcome to HORTICULTURE UPDATE!
The paper form of ‘Lawn and Garden Update' that we have been sending out monthly is being replaced. We invite you to visit this first issue of our ‘Horticulture Update' newsletter that will be appearing regularly in electronic form from now on.
‘Horticulture Update' is designed as a source of information for County Extension Agents and Specialists to utilize in local news releases and as part of their educational programs across Texas, but will also appeal to gardeners and plant-lovers of all kinds, especially those interested in growing plants under the tough conditions of Texas and the Southern United States. Our information is oriented for Texas gardeners and Texas conditions.
Each issue includes a monthly checklist for suggested garden activities along with articles on gardening topics and profiles of plants especially suitable for Texas and the South. Another feature of the publication is information about forthcoming educational opportunities sponsored by the Texas Agricultural Extension Service.
Dr. Doug Welsh and I will share editorial responsibilities for the newsletter. Articles from County Extension Agents (Horticulture) and specialists in related disciplines are welcome and encouraged. Doug and I are both Extension Horticulturists in the Department of Horticultural Sciences at Texas A & M University.
CONTENTS
- July-August Plant of the Month: Hardy Hibiscus
- The Care and Handling of Cut Plant Materials
- Gomphrena globosa, Bachelor Buttons
- August is the Time to Sow Seeds for Fall Transplants
- Landscape Design Study Course No. IV, Series XVII
- Garden Checklist for July and August
Hardy Hibiscus
By Dr. William C. Welch, Landscape Horticulturist
The giant rose mallow has the largest flowers of any hardy perennial. Some of the hybrids may be one foot in diameter. Rich, moist soil and full sun bring the most vigorous growth, but mallows are very accommodating, and will tolerate light shade and less desirable soils. Giant rose mallows will flower from seed the first year if started very early in spring. Favorite cultivars may be rooted from cuttings during the growing season. Colors range from crimson, white, pink, rose, and in-between.
Giant rose mallows are relatives of the native hibiscus found in Louisiana and other Gulf South states. They are among the most spectacular and easily grown plants for use in the border. Following the spring and summer growing season, the plants freeze back to the ground each fall. Old stems should be cut back to a height several inches above the ground. New shoots emerge by mid-spring, and the plants quickly develop handsome mounds of foliage and flowers by early summer. Individual flowers last only a day, but each plant may flaunt several flowers at once. Numerous seedling selections, such as 'Southern Belle' and 'Frisbee' are offered in good seed catalogs. Few garden plants provide so much enjoyment for so little care.
Seeds of giant rose mallows are available from catalogs, while container-grown plants are usually in stock at Texas garden centers and nurseries. Color selection is possible when you purchase blooming-size plants. If growing giant rose mallows from seed, it is important to start them early in the season so that they will have adequate time to develop before freezing weather sets in.
Hibiscus mutabilis is an old-fashioned perennial or shrub hibiscus better known as the Confederate rose. It tends to be shrubby or treelike in Zones 9 and 10, though it behaves more like a perennial further north. Flowers are double and are 4 to 6 inches in diameter; they open white or pink, and change to deep red by evening. The 'Rubra' variety has red flowers. Bloom season usually lasts from summer through fall. Propagation by cuttings root easiest in early spring, but cuttings can be taken at almost any time. When it does not freeze, the Confederate rose can reach heights of 12 to 15 feet with a woody trunk; however, a multi-trunk bush 6 to 8 feet tall is more typical. Once a very common plant throughout the South, Confederate rose is an interesting and attractive plant that grows in full sun or partial shade, and prefers rich, well-drained soil.
Hibiscus coccineus is better known as the Texas Star Hibiscus. It has large, single, red flowers about 3 to 4 inches in diameter that appear atop branches of palmately lobed leaves with three to seven segments. Culture is very easy, with well-drained soil, an annual application of fertilizer in spring or early summer, and a sunny location being most important. Texas Star Hibiscus may be propagated from seed or cuttings. Mulching the plants in wintertime prevents root injury during very cold weather. Old stems, if they freeze, should be pruned back to the ground in early spring. Even if frost damage has not occurred, it is still a good idea to prune back and shape the plants before growth begins.
Consider hardy types of hibiscus for the back of flower borders where their impressive flowers can appear over other summer flowering plants. Some gardeners and landscape professionals plant daylilies, lantana, gomphrena, zinnias, portulaca, purslane, celosias or other summer annuals and perennials in front of their hardy hibiscus groupings.
Several years ago, Dr. Jerry Parsons, Extension Horticulturist located in San Antonio, released a new giant rose mallow named 'Moy Grande' from the San Antonio Botanical Garden. 'Moy Grande' has huge flowers of dark rosy pink. Best availability is in the San Antonio area.
Chinese hibiscus offer an excellent source of summer color in the landscape, and are among our most popular tropical and subtropical flowering plants. Popularity in Texas appears to be increasing in recent years, although insects, diseases, and winter injury limit their use. Even the southernmost extremes of Texas occasionally experience sufficient cold to kill this plant. With this in mind, Hibiscus rosa sinensis should be grown as an annual or container specimen in most of the state. In areas where winter does not cause damage, hibiscus is a perennial, and may be used as a more permanent landscape plant.
The glossy green foliage varies considerably in size and texture among the many varieties. Flowers range from 4 to 8 inches in diameter, and may be double or single. Hibiscus belong to the mallow family and are closely related to cotton, hollyhock, Turks cap, the mallows, shrub althaea, Confederate rose, and okra. Colors vary from white through pink, red, yellow, apricot, and orange. Generally, the single-flower hibiscus bloom more, and, therefore, offer a bigger show in the landscape, but doubles are sometimes preferred for their spectacular individual flowers.
Hibiscus flowers are popular for decoration. They need not be placed in water to prevent wilting, which adds flexibility to their use. An objection is that the flowers of most varieties last only one day, especially during hot weather. To keep flowers open until evening, pull blooms as soon as they are fully open in the morning, and keep in the refrigerator until just before using. If no leaves are pulled with the blossoms, picking does not damage the plant or reduce the total amount of flowering.
Hibiscus prefer a sunny location and well drained soil containing plenty of organic matter and nutrients. From April through September, small monthly applications of a complete fertilizer are beneficial. Container-grown plants will require more frequent applications. To bloom and grow profusely, hibiscus must have sufficient water. As with most other plants, watering should be done thoroughly and not too frequently. Some protection from strong winds is necessary, since the flowers are easily damaged.
It should be remembered that hibiscus are not cold hardy. If your area is subject to freezing temperatures, your Chinese hibiscus must either be treated as annuals and allowed to freeze or be protected during cold weather. During mild winters, plants may freeze to the ground and then sprout from the base the following spring. Applying a loose mulch, such as pine straw or oak leaves, around the base of the plant before cold weather sometimes prevents severe winter injury. Certain varieties are more susceptible to cold damage than others. If greenhouse space is available, plants may be dug, placed in containers, and replanted in the landscape after the danger of frost has passed.
In recent years, there has been an increase in use of hibiscus as container plants. Small plants may be purchased early in spring or summer, placed in large pots (at least 12 inches in diameter) and enjoyed until frost.
The following information is provided by
Jim Johnson, AAF, AIFD, TMF, Director of the Benz School of Floral Design at Texas A & M University, and Kimberly Williams, SAIFD.
- Harvest garden flowers during the coolest time of day when they are crisp and turgid — early morning or late evening. However, if the flowers have been purchased, remove the wrappings and bindings so the stems can be separated.
- Remove lower foliage that would remain underwater in the storage container.
- Cut stems with a sharp instrument, making the cuts underwater if possible. This prevents air bubbles from ‘clogging’ the stems.
- Place the materials in clean containers of lukewarm water with preservative added (room temperature up to 100 degrees F.).
- Always keep cut material in water while designing. This will prevent wilt due to the loss of water through transpiration.
- Always design in clean containers that have been filled with preservative water.
- After each use, clean storage containers, vases, liners, and needle point holders with a soapy Clorox7 solution, to kill all bacteria.
- Use a floral preservative to provide nutrients and to prevent bacterial growth.
Floral Preservatives
The formula for floral preservatives is simple. [Commercial floral preservatives may be purchased in liquid or powder form at retail florists. Be sure to follow the instructions exactly as written. A perfectly acceptable home substitute is Listerine7 mouthwash [one ounce of Listerine per gallon of water will provide the correct solution)].
It consists of three prime ingredients:
- Sugar (dextrose, not table sugar). It provides a carbohydrate energy source so flowers can carry on the process of respiration. This helps buds to develop into flowers.
- Biocide (controls the growth of bacteria). Without it, the addition of sugar to lukewarm water would increase bacteria which would plug the stems and shorten the life of the cut flower.
- Acidifier (lowers the pH of the water and improves water uptake).
Special Treatments
Plants vary in composition and growth habit; therefore, care and handling techniques may vary.
- Avoid using the tender new growth of most plants, as it has not developed a cell structure sturdy enough to keep it from wilting.
- Short-lived blossoms such as daylilies, hibiscus, iris, lotus, magnolia, and passion flowers should be cut in the bud stage and allowed to open in the finished design.
- The long standing practice of crushing woody stems is not recommended, because this damages the cell structure and actually impedes water uptake. Make a clean cut instead.
- Blossoms with tremendous petal surface area compared to their small stem size benefit from being submerged in water at room temperature.
- Depending on their petal substance and color, blossoms can remain underwater for a few minutes (white and pastel camellias, gardenias, orchids and roses) to a few hours (anthuriums, gerberas, hydrangeas, lilacs, dark colored roses and most other tropical flowers).
- Wilted flowers can be revived by cutting the stem underwater and submerging the entire flower until revived.
By Dr. William C. Welch, Landscape Horticulturist
As we approach the most stressful period of the year for most garden plants, the few species that really thrive in hot, dry conditions deserve special recognition. Bachelor Buttons are readily available and easily grown from seed.
According to Hortus Third, Bachelor Buttons came to us from tropical areas of the Old World. They are documented as having been a part of early American gardens. Colors range from purple, rose, orange and white, and flowers are about l inch across.
In addition to their ease of culture, Bachelor Buttons were popular with our ancestors for their use as “everlastings.” Dozens of individual flowers occur on each plant which are attractive mounds about 2 feet tall and wide. Cut stems of flowers hung upside down in a dark, dry area and allowed to dry hold their color for a year or more and can be used in a variety of ways.
Experienced gardeners always save a few flower heads from their favorite color plants to use for next year’s seed. This is definitely a plant that will not thrive until hot weather arrives. June and July are good times to plant the seeds in most of Texas. Bachelor Buttons are so easily grown and transplanted that many gardeners simply sow the seeds in a small area of the vegetable garden or flower border then transplant seedlings to permanent locations when 2 or 3 inches tall. Plants are usually spaced l to l-l/2 feet apart for a mass effect. They are normally attractive in the garden until late fall. Dwarf forms are available, but appear to be more susceptible to rot.
Few insects seem to bother Gomphrena but occasional loss occurs from root rot. Good drainage is essential but little fertilizer or water are necessary to produce a massive display. It’s not too late to start new plants now from seed. Plants started in July or early August can make a beautiful fall display and provide lots of dried material for winter decoration.
By Dr. William C. Welch, Landscape Horticulturist
If you haven’t already done so, this is the time to begin sowing seeds for fall transplants. By starting now you can have:
- Pansies
- Calendulas
- Johnny-Jump-Ups (violas)
- Flowering cabbage
- Flowering kale
- Broccoli
- Cauliflower
- Cabbage
- Chinese cabbage
- Lettuce
If starting your own transplants has been disastrous for you in the past, especially in the spring, then take heart because starting fall transplants is easier. Since the soil is not as cool as it is in spring, there is not much damping-off disease. Gardeners are able to start the transplants outside where they can get plenty of sunlight. But, it is best if the transplants don’t get too much sun - morning sun and afternoon shade make a good combination.
Although many containers can be used to grow seeds, the most convenient I’ve found is the foam coffee cup discarded by people whenever they take a coffee break. Simply poke three or four holes in the side at the bottom of the cup. Write the name of the variety being planted on the side of the cup where it will remain without getting lost, as so often happens if you use labels. An additional advantage of the coffee cups is that they’re white and reflect heat.
The next major concern is a potting soil mix. Many standard potting soils will work fairly well, but you can make your own. To one bushel each of vermiculite and peat moss (finely ground pine bark can be substituted for peat moss), add 10 tablespoons of 0-20-0 (superphosphate) and 1/2 cup of garden fertilizer, such as 12-24-12. Mix the material thoroughly by putting the ingredients out on the drive, scooping into the bottom and throwing each shovel-full on top, pyramid fashion. Another technique is to roll the mixture back and forth in an old tarp. The soil should be slightly watered down so it’s damp but not soggy.
Most seeds should be barely covered with the soil mix, but some tiny seeds like lettuce should not be covered at all. Water them in thoroughly, preferably by setting them in a pan of water and allowing the soil to soak from the bottom. Allow the containers to drain and then put them in a plastic bag out of sunlight. Within a few days the seedlings will begin to grow. As soon as this happens, take the containers out of the bags and put them in a well-ventilated area. As the seedlings begin to make growth, use any soluble houseplant fertilizer to keep them growing vigorously.
If you’ve had problems with disease in the past, you might want to use a fungicide twice: once at planting and again at germination. Lightly dust the seeds prior to planting. A fungicide can also be used to drench young seedlings just as they come up. Before you know it, you’ll have a pot full of tiny seedlings that can either be transplanted into individual containers, or if there aren’t too many in the pot, held until time to go into the garden. Perhaps the simplest technique is just to plant two or three seeds in each pot, thinning them to one plant after a few weeks.
If you opt for transplanting, be sure that you handle the young seedling only by the leaves. If you grasp the stem and damage it to any extent, the young seedling will be stunted. Pots for transplants should be filled to within 1/4 inch of the rim. A pencil can be used to make a hole in the center of the potting soil mixture. This is where a little moisture is critical; dry soil won’t allow the hole to stay open. Carefully lower the seedling roots into the hole and then use the pencil again in a lever-like action to firm the soil against the root system. Be sure to water the plants carefully, picking up any that get knocked into the soil. Before you know it, you’ll be eating delicious, home grown broccoli.
NO. IV, SERIES XVII
September 20 - 22, 2000
The Landscape Design Study Courses are presented by Texas Garden Clubs, Inc., and the Texas Agricultural Extension Service. The program is offered in four separate schools, approximately six months apart, in the Bryan-College Station area. Participants may take the four courses in any sequence. Topics to be covered at this session include: Development of Landscape Architecture from World War II to Present; Contemporary Landscape Design; Designs for the Future; Redesign of Areas; Herbaceous Materials in the Landscape; Community Participation - Organization and Individual Responsibility; and Evaluating the Landscape Designs of Residential, Public, and Business Property.
Garden club members, Master Gardeners, nurserymen and others who are interested in furthering their knowledge of landscape design are welcome to attend. (Master Gardeners who complete a course may apply 12 hours of credit to their requirements for continuing education). Texas Garden Club members who successfully pass the examinations for all four courses are eligible to become nationally accredited Landscape Design Critics. Texas Certified Nursery Professionals who pass the course may apply this to their requirement for recertification with the Texas Nursery and Landscape Association (TNLA).
Registration fee will be $60.00. No refunds will be made after September 1, 2000. For information please contact Ms. Jacque Hand, Texas A&M University Conferences and Short Courses, Drawer H-1, College Station, TX 77844 (telephone 979-845-7692, or 979-845-8904).
FACULTY
McCoy, Mrs. Hazel, Chairman, Landscape Design Study Courses, Texas Garden Clubs, Inc.
Welch, William C., Professor and Extension Horticulturist, Texas A&M University
Volkman, Nancy, Associate Professor, Department of Landscape Architecture and Urban Planning, Texas A&M University
Ruth, Robert, Landscape Architect, Bryan-College Station, Texas
King, W. Alan, Landscape Architect, Bryan-College Station, Texas
Ellis, Chris, Assistant Professor, Department of Landscape Architecture, Texas A&M University
Novak, Joseph, Senior Lecturer, Department of Horticultural Sciences, Texas A&M University
Shafer, C. Scott, Assistant Professor, Recreation and Parks Department, Texas A&M University
You may register by printing the Registration form, and sending it, with your check for $60.00 to Ms. Jacque Hand, Texas A&M University Conferences and Short Courses, Drawer H-1, College Station, TX 77844.
By Dr. William C. Welch, Landscape Horticulturist
- Re-blooming salvias, such as Salvia greggii and S. farinacea, should be pruned back periodically during the summer. To make the job easier, use hedging shears, and remove only the spent flowers and a few inches of stem below. Fall-blooming perennials, such as Mexican marigold mint (Tagetes lucida), chrysanthemums, physostegia, and Salvia leucantha, should be pruned in the same manner during the summer to keep them compact, reducing the need for staking. This type of pruning should be completed prior to September 1, since flower buds begin forming about that time.
- Take a critical look at your landscape while at the height of summer development. Make notes of how you think it can be better arranged, plants that need replacement, overgrown plants that need to be removed, and possible activity areas that can be enjoyed by family members.
- Check for insects and diseases. Destroy badly infested plants. Spider mites can be especially troublesome at this time. Select a chemical or organic control, or use insecticidal soap.
- During the summer, soil moisture becomes extremely important and essential for good plant production. Because continual watering is oftentimes costly and time consuming, it pays to conserve the moisture around plants. This is best done by mulching. A good mulch will retain valuable moisture needed for plant growth, and improve overall gardening success. Mulches are usually applied 2 to 6 inches deep, depending on the material used. In general, the coarser the material, the deeper the mulch. For example, a 2-inch layer of cottonseed hulls will have about the same mulching effect as 6 inches of oat straw or 4 inches of coastal Bermuda hay.
- There is still time to plant some of the colorful, heat-tolerant summer annuals. You can direct-seed zinnias and portulaca, and purchase plants of periwinkle, salvia, marigold,gomphrena, celosia, and purslane. Be sure to water transplants as needed until roots become established.
- Removing faded flowers from plants before they set seed will keep them growing and producing more flowers. A light application of fertilizer every 4 to 6 weeks will also be helpful.
- Now is the time to plan for next spring. Consider digging and dividing any crowded spring bulbs. Once the bulbs have matured and the foliage has turned brown, it is time to spade them up and thin out the stand. Crowded bulbs produce fewer and smaller blooms. They usually need thinning every 3 to 4 years.
- Caladiums require plenty of water at this time of year if they are to remain lush and active until fall. Fertilize with 21-0-0 at the rate of one-third to one-half pound per 100 square feet of bed area, and water thoroughly.
- Prune out dead or diseased wood from trees and shrubs. Hold off on major pruning from now until midwinter. Severe pruning at this time will only stimulate tender new growth prior to frost.
- Sow seeds of snapdragons, dianthus, pansies, calendulas, and other cool-season flowers in flats, or in well-prepared areas of the garden, for planting outside during mid-to-late fall.
- Plant bluebonnet and other spring wildflowers. They must germinate in late summer or early fall, develop good root systems, and be ready to grow in spring when the weather warms. Plant seed in well-prepared soil, one-half inch deep, and water thoroughly.
- Picking flowers frequently encourages most annuals and perennials to flower even more abundantly.
- It is time to divide spring-flowering perennials, such as iris, Shasta daisy, oxeye, gaillardia, cannas, day lilies, violets, liriope, and ajuga.
- Make your selections and place orders for spring-flowering bulbs now so that they will arrive in time for planting in October and November.
- Don’t allow plants with green fruit or berries to suffer from lack of moisture.
- A late-summer pruning of rosebushes can be beneficial. Prune out dead canes and any weak, brushy growth. Cut back tall, vigorous bushes to about 30 inches. After pruning, apply fertilizer, and water thoroughly. If a preventive disease-control program has been maintained, your rose bushes should be ready to provide an excellent crop of flowers this fall.
- It is not too late to set out another planting of many warm-season annuals, such as marigolds, zinnias, and periwinkles. They will require extra attention for the first few weeks, but should provide you with color during late September, October, and November.
- Establish a new compost pile to accommodate the fall leaf accumulation.