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December 2010
INTERIOR PLANTSCAPE SYPOSIUMFERTILIZATION OF INTERIOR PLANTS: CHECKING FERTILIZER LEVELS IN PLANTS YOU’VE HAD FOR SOME TIME
THE DOS AND DON’TS OF POINSETTIA CARE
REAL CHRISTMAS TREES ARE ‘GREENER’ THAN ARTIFICIAL ONES
IS YOUR CERTIFICATION CURRENT?
INTERIOR PLANTSCAPE SYPOSIUM
You asked for training from PLANET and now, for the first time, PLANET and OFA have partnered to provide up-to-date, practical training for the front line! Mark your calendar and plan to join us for a one-day, Interior Landscaping Symposium at Longwood Gardens, Kennett Square, Pennsylvania, on April 14, 2011. There’ll be education, networking, and presentations by the industry’s leading interior landscapers. This symposium will offer CEUs toward Landscape Industry Certified Technician recertification as well as pesticide credits. More information will be available soon at LandcareNetwork.org!
FERTILIZATION OF INTERIOR PLANTS: FERTILIZER LEVELS IN PLANTS YOU’VE HAD FOR SOME TIME
By Lynn P. Griffith
In last month’s issue, we learned about checking fertilizer level in plants recently acquired from a nursery or other source (Part I of “Fertilization of Interior Plants”). But, what about plants you’ve had for a while? You can probably assume that whatever fertilizer the nursery may have used is long gone. So what should you do to ensure the proper level of fertilization for them?
For plants you’ve had for a while, especially those you want to have more growth or color, you will probably need to add a small amount of fertilizer from time to time, particularly in the brighter, warmer months. If you are applying a soluble fertilizer at the full rate in low-light settings, do not apply more than two or three times per year. You may fertilize less frequently or at lower rates where significant growth is not desired. Watch the new growth of your plants carefully. New leaves that are normal in size and of decent color are a sign that your fertilization is probably adequate. If the new leaves are smaller or more yellow than normal, this is likely a sign that some fertilizer is needed.
In winter or in very low-light environments, fertilizers that are high in nitrate nitrogen are preferable to those with ammonia or urea. For example, the soluble 20-10-20 fertilizers have a lot more nitrate nitrogen than most 20-20-20 formulations. Nitrate nitrogen gives you a somewhat more controlled, less stretchy growth, with a somewhat reduced risk of ammonia toxicity. Usually, a teaspoon per gallon is a pretty good rule of thumb, although you may sometimes want to use more or less, depending on plant size, species, and light levels. Be aware that most 20-20-20 and 20-10-20 fertilizers contain little or no magnesium, and frequently no calcium or sulfur. It is not a bad idea to add a teaspoon of Epsom salts (magnesium sulfate) once or twice a year with your soluble fertilizer in order to make sure that magnesium and sulfur requirements are taken care of. Calcium is usually supplied either from the irrigation water or from the lime the grower used for the potting mix.
Such a program should serve you well for the major and secondary plant nutrients. Sometimes interior plants have micronutrients problems, usually iron, manganese, or occasionally boron. Zinc and copper deficiencies are rare in interiors. The Sprint or Sequestrene products are popular sources of chelated iron. There are other good sources of chelated iron as well; however, I don’t care for lignan sulfonate sources for tropicals. Manganese sulfate works fine as a manganese source. Glucoheptonate chelates are also popular with foliage growers requiring a broad spectrum source of trace elements. For Interior landscapers, it is usually best to apply your micronutrients as a drench, which often works faster and is less likely to cause messy conditions from over spray or to stain surfaces such as masonry, carpet, or tile.
Trace element deficiencies are not uncommon in interior plants. Iron deficiency is common in Rhapis, Janet Craig, Aglaonema, and Fishtails and Majesty palms just to name a few. The symptom is usually a vein-like discoloration in the new leaves. The symptoms from a lack of manganese are similar to those from a lack of iron. Lack of manganese is common in Marginata, many Ficus species, and Kentias and Phoenix palms. Manganese sulfate drenches will usually take care of this if the root system is healthy.
Magnesium deficiency generally occurs in older leaves. This is common in Aglaonema, Anthurium, Pothos, Heliconia, Philodendron, and Spathiphyllum to name a few. An Epsom salts drench will often cure a magnesium deficiency, but it may take a little time for the symptoms to disappear. Lack of nitrogen results in small, pale new leaves that sometimes may be distorted. You will see this at times on Aglaonema, Pothos, Philodendrons, and Spath. Lack of potassium often shows up in older leaves as a leaf edge burn or necrotic leaf spotting, especially in palms. Watch for leaf spots also on Fishtail, Rhapis, Anthurium, and Heliconia.
If your fertilization level is high, leach once or twice with clear, low-saline water in order to reduce the fertilizer salts. Sometimes however, you can’t leach very easily without drowning the plant or flooding an area. In those situations, you can irrigate the plant with sugar water. Sugar stimulates the soil microbes to eat up the fertilizer salts. This technique does work, and about five pounds of white or brown sugar per 100 gallons is usually enough. Water the plant in the normal fashion with the sugar water, and in a couple of weeks the salt level should drop significantly. In cases of very high salts, expect to apply the sugar and water drench multiple times and continue to monitor your soluble salt level until it is adequately reduced.
With a little monitoring, some communication with your growers, and knowledge of the requirements of the plant varieties you maintain, you can maintain a simple yet relatively inexpensive fertility program. If you have a significant plant problem or you are stumped as to where your fertility levels are, soil testing laboratories can provide more specific fertility information.
THE DOS AND DON’TS OF POINSETTIA CARE
It’s again the time of year when poinsettias are everywhere. They are often central to the displays in malls and churches, and help to decorate many a home. Following are some tips to keep them looking their best throughout the holidays:
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DO place your plant in indirect sunlight for at least six hours per day. If direct sun can’t be avoided, diffuse the light with a shade or sheer curtain.
- DO provide room temperatures between 68° and 70°F. Generally speaking, if you are comfortable, so is your poinsettia.
- DO water your plant when the soil feels dry to the touch.
- DON’T place plants near cold drafts or excessive heat. Avoid placing plants near appliances, fireplaces, or ventilating ducts.
- DON’T expose plants to temperatures below 50°F. Poinsettias are sensitive to cold, so avoid placing them outside during the winter months.
- DON’T overwater your plant or allow it to sit in standing water. Always remove a plant from any decorative container before watering, and allow the water to drain completely.
- DON’T expose your plant to chilling winds when transporting it.
- DON’T fertilize your plant when it is in bloom.
The widespread belief that poinsettias are poisonous is a misconception. The scientific evidence demonstrating the poinsettia’s safety is ample and well documented.
In studies conducted by The Ohio State University in cooperation with the Society of American Florists, no toxicity was evident at experimental ingestion levels far exceeding those likely to occur in a home environment. In fact, the POISINDEX® Information Service, the primary information resource used by most poison control centers, states that a 50-pound child would have to ingest more than 500 poinsettia bracts to surpass experimental doses. Yet, even at this high level, no toxicity was demonstrated.
As with all ornamental plants, poinsettias are not intended for human or animal consumption, and certain individuals may experience an allergic reaction to poinsettias. However, the poinsettia has been demonstrated to be a safe plant. In fact, in 1992, the poinsettia was included on the list of houseplants most helpful in removing pollutants from indoor air. So, not only is the poinsettia a safe and beautiful addition to your holiday decor, it can even help keep your indoor air clean!
REAL CHRISTMAS TREES ARE ‘GREENER’ THAN ARTIFICIAL ONES
 AFP/Getty Images/File — The 2009 U.S. Capitol Christmas tree in Washington, D.C. Andrea Thompson |
It may not sound like “tree-hugging,” but cutting down a real tree for Christmas is actually greener than going with the artificial kind, one scientist says. “It is a little counterintuitive to people,” explains Clint Springer, a biologist at Saint Joseph’s University in Philadelphia. Because of concerns over deforestation around the world, many people naturally worry that buying a real tree might contribute to the problem, Springer says. But, these days, most Christmas trees for sale are not grown in the forest, but on tree farms, for the express purpose of being cut. The tree farms also replant after the trees are cut. Moreover, from a greenhouse gas perspective, real trees are “the obvious choice,” Springer told LiveScience.
Live trees actively photosynthesize as they grow from saplings, which remove carbon dioxide from the atmosphere. After they have been cut and Christmas is over, they’re usually chipped for mulch. As mulch, the bits of tree decompose very slowly, releasing carbon dioxide back into the atmosphere. So, in the end, a real Christmas tree is carbon neutral, putting the same amount of carbon dioxide back into the air as it took out (albeit much more slowly).
Artificial trees, on the other hand, don’t come out even in the carbon balance. Petroleum is used to make the plastics in the trees and a lot of carbon dioxide-creating energy is required to make and transport them. Because these trees just end up in landfills after a few years’ use, “those greenhouse gases are lost forever,” Springer says. “There’s really no opportunity to recycle those.” Springer suspects that artificial trees have become more popular in recent years because they are more convenient.
Adding to incentives to “go real,” this Christmas may also be economic concerns. Most artificial trees are produced in China, while real trees tend to be grown on local farms, Springer adds.
IS YOUR CERTIFICATION CURRENT?
Have you checked the good-through date on your PLANET certification wallet card recently? If it is December 31, 2010, now is the time to recertify by completing and submitting your CEU Submission Form. When you recertify, you’ll receive a rebranded certificate, lapel pin, and wallet card reflecting your new good-through date.
For an upcoming opportunity to earn continuing education units (CEUs) toward your Landscape Industry Recertification, check out the Train-the-Trainer session held in conjunction with TPIE (Tropical Plant Industry Expo) in Fort Lauderdale, FL on Thursday, 20, 2011 from 2:00 to 5:00 PM at the Fort Lauderdale Convention Center. For information about opportunities to earn continuing education units (CEUs), check out the revised recertification requirements sheet. If the educational opportunity is green industry or job related — it will qualify. Webinars, articles, or books as part of self-study and in-house training are some examples of how you can accumulate CEUs in your two-year recertification cycle. Also, check the Recertification Frequently Asked Questions section regularly for updates about recertification.
NOTE: If your wallet card good-through date is 2009, your certification has lapsed. Please contact PLANET immediately at (800) 395-2522.
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