JUNE PLANT OF THE MONTH . . . HIBISCUS
By Dr. William C. Welch, Landscape Horticulturist
Texas A&M University, College Station, Texas
GIANT ROSE MALLOW, HIBISCUS MOSCHEUTOS
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.
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, HIBISCUS ROSA SINENSIS
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 least12 inches in diameter) and enjoyed until frost.
CUT PLANT MATERIALS
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.
CARE AND HANDLING OF CUT PLANT MATERIALS
1. 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.
2. Remove lower foliage that would remain underwater in the storage container.
3. Cut stems with a sharp instrument, making the cuts underwater if possible. This prevents air bubbles from 'clogging' the stems.
4. Place the materials in clean containers of lukewarm water with preservative added (room temperature up to 100 degrees F.).
5. Always keep cut material in water while designing. This will prevent wilt due to the loss of water through transpiration.
6. Always design in clean containers that have been filled with preservative water.
7. After each use, clean storage containers, vases, liners, and needle point holders with a soapy Clorox7 solution, to kill all bacteria.
8. Use a floral preservative to provide nutrients and to prevent bacterial growth.
The formula for floral preservatives* is simple. 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).
* 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).
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.
LANDSCAPE DESIGN STUDY COURSE IV
The fourth in a series of landscape design study courses will be held September 28-30 in Bryan.
Although this is the last part of the series, participants interested in attending are encouraged to do so and can enter the program with any of the four courses.
Course IV includes a tour and evaluation of several Bryan-College Station landscapes. The program is cosponsored by Texas Garden Clubs, Inc., and the Texas Agricultural Extension Service, and is open to anyone interested in furthering their knowledge of landscape design. Many Master Gardeners have found the courses useful as an extension of their training. It is also approved for Master Gardener Continuing Education Credit in Texas.
For program and registration information, contact the Extension Horticulture Office at (409) 845-7341.
STRETCHING YOUR GARDEN DOLLAR
By Ted Fisher, Extension Horticulturist
Cherokee County, Texas
Many Texas home owners are unfamiliar with the art and technique of gardening, and spend needless dollars each year on landscaping. Although dollars spent on landscaping can pay big dividends, the trick is to stretch those dollars and make the most of the money invested. Here are some money-saving dollar-stretching suggestions for you to consider:
+ Purchasing the biggest trees is not always a wise investment when landscaping your home. These big trees are often set back drastically during digging and transplanting, and may take years to recover from transplanting shock. Many times, a smaller tree will re-establish itself more rapidly, producing a nicer tree in a shorter time period. With the money you save buying smaller trees, you can get a good start on the rest of your landscape. High-quality trees are a good investment. Although there is a time and place for 'fast growers', do not overlook the dependable oak varieties, cedar elm, bald cypress, and Chinese pistachio. They will last longer, and you will have fewer insect, disease, and pruning headaches in the meantime. Beware of door-to-door tree trimmers who insist that topping your tree is a good idea. Topping trees opens up large wounds, leaving them vulnerable to insects, disease, and decay.
+ Select plants well adapted to your area. There are excellent choices available, including many interesting native varieties. You may not have the most unique landscape on the block, but at least it will be healthy.
+ When using chemicals, read and follow label directions carefully to avoid mistakes and save money. You can ruin quality plants by spraying before reading. Using the wrong insecticide in your vegetable garden may make the harvest unsafe for the dinner table.
+ Choose your fertilizer carefully. The three numbers on each bag (16-4-8, 15-0-5, for example) indicate nitrogen, phosphorus, and potassium content, respectively. To promote leaf growth on any plant, choose a fertilizer high in nitrogen. For improved flower and fruit production, select a fertilizer high in phosphorus. Potassium (potash) is seldom lacking in our clay soil, so do not pay extra to get it.
+ Save money by making and using compost as a soil conditioner. Any home landscape has an out-of-the-way spot large enough to accommodate a compost pile. This not only saves money spent on peat moss, but it gives you an easy way to dispose of leaves and grass clippings.
+ Beware of 'miracle' products that may or may not aid your landscape or garden. Every year, dozens of deceptive products hit the market. If it sounds too good to be true, it probably is. Read labels carefully, and use common sense with regard to unbelievable claims.
+ Top-dressing your lawn with sand or soil on a regular basis is not a recommended practice. While minor low spots can be corrected this way, you can easily overdo it and smother your lawn. Using topsoil from an unknown source may also introduce undesirable plants and weeds into the landscape, creating additional work and expense to correct the problem.
+ Shop and compare. While many nursery and garden supplier prices are competitive for many products, prices do vary for nursery stock and plant materials. Check several nurseries before buying, to be certain you are getting the best price for quality merchandise.
CRAPE MYRTLE CARE
By Dr. William C. Welch, Landscape Horticulturist
Texas A&M University, College Station
Summer in Texas would not be complete without the abundance of crape myrtle flowers now beginning to be conspicuous over most of the state. Proper fertilization and pruning usually result in a long display of flowers of three months or more.
Fertilizer recommendations are best made after reviewing soil test results, but a general recommendation of 2 pounds of nitrogen per 1,000 square feet of root area is sufficient for most trees and shrubs. This can be repeated again in the late fall. The first application should be made just before new growth begins in the spring. The number of square feet in the root area is determined by the branch spread of the tree.
The most significant disease affecting crape myrtle is powdery mildew. This can be controlled by spraying with Benomyl or Funginex, used according to label instructions. Mildew is usually less of a problem if plants are located in open sunny areas where air circulation is good.
Pruning is best done in late winter before new growth begins. The structure and trunks of crape myrtle are among their chief assets; therefore, pruning should normally involve only removing dead and twiggy growth to expose the sculptural character of the tree.
For dwarf varieties or in shrub borders where crape myrtles may be grown only for their blooms, severe pruning will help insure larger and more prolific flowers. The pruning of faded and seedy blossom heads will usually promote repeat blooming late in the summer.
For something different, try some of the dwarf type crape myrtles in tubs or pots on the terrace. They do best in sunny areas, and are as satisfactory for container use as they are in the ground.
GARDEN PROBLEM GUIDE
This article appeared in EarthKind Landscape and Gardening Guide, 1997-1998, produced by the Texas Agricultural Extension Service, College Station.
Symptom: Dying young plants
Possible Causes: Fertilizer burn. Disease (damping off).
Possible Cures: Mix fertilizer thoroughly with soil. Use treated seed.
Symptom: Stunted plants ÷ pale to yellow
Possible Causes: Low soil fertility. Poor soil drainage. Shallow or compacted soil. Insects or diseases. Nematodes.
Possible Cures: Soil test for fertilizer recommendations. Add organic matter. Work soil deeper. Identify and use control measures. Use approved chemicals.
Symptom: Stunted plants ÷ purplish color
Possible Causes: Low temperature. Lack of phosphorus.
Possible Cures: Plant at recommended time. Add phosphorus fertilizer.
Symptom: Holes in leaves
Possible Causes: Insects. Hail.
Possible Cures: Identify and use control measures. Be thankful it was not worse.
Symptom: Spots, molds, darkened areas on leaves and stems.
Possible Causes: Disease. Chemical burn. Fertilizer burn.
Possible Cures: Identify, spray, or dust; use recommended rate and time. Use recommended chemicals at recommended rate and time. Keep fertilizer off plants.
Symptom: Wilting plants.
Possible Causes: Dry soil. Excess soil moisture. Disease.
Possible Cures: Irrigate if possible. Avoid over-watering. Use resistant varieties if possible.
Symptom: Weak, spindly plants
Possible Causes: Too much shade. Plants too thick. Too much nitrogen.
Possible Cures: Move garden to sunny area. Seed at recommended rate. Avoid excess fertilization.
Symptom: Failure to set fruit.
Possible Causes: Improper temperatures. Too much nitrogen. Insects.
Possible Cures: Follow recommended planting time. Avoid excess fertilization. Identify and use control measures.
Symptom: Tomato leaf curl
Possible Cause : Heavy pruning in hot weather.
Possible Cure: Do not prune; use cages.
Symptom: Dry brown-to-black rot on blossom end of tomato
Possible Causes: Low soil calcium. Extremely dry soil.
Possible Cures: Add gypsum. Irrigate and mulch.
Symptom: Misshapen tomatoes (catfacing)
Possible Cause: Cool weather during blooming.
Possible Cure: Plant at recommended time.
Symptom: Abnormal leaves and growth
Possible Causes: 2, 4-D weed killer. Virus disease.
Possible Cures: Do not use sprayer that has previously applied 2,3-D; do not allow spray to drift to garden. Remove infected plants to prevent spreading control insects that transmit.
GARDEN CHECKLIST FOR JUNE
By Dr. William C. Welch, Landscape Horticulturist
Texas A&M University, College Station
+ 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, 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.
+ House plants can be moved out of doors this month. Sink the pots in a cool, shaded garden bed to prevent them from drying out so quickly; water pots, container plants, and hanging baskets often. Monthly feedings with house plant fertilizer will encourage continued growth.
+ 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.
+ June is the time to select daylily varieties as they reach their peak of bloom.
+ Fertilize roses every 4 to 6 weeks. Apply small amounts of an organic or chemical fertilizer immediately after a flush of bloom, or every 4 to 6 weeks.
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