Wednesday, November 18, 2009
Poinsettias do well in the home and keep their color until mid-March. The showy red, pink, white, yellow, bicolored or speckled modified "leaves" are called bracts. With proper light and temperature, they accumulate the anthocyanin pigments that give them their color. The flowers (botanically called cyathia) of the poinsettia are in the center of the bracts. Male and female parts are present, along with a yellow-edged nectary with sweet, fragrant nectar. Make sure that flowers are present and healthy for a longer display in your home.
When outside temperatures approach 35 degrees F, be sure the plant is well wrapped or sleeved before transporting. Low temperatures, even for short periods, can damage leaves and bracts. Remove sleeves promptly to prevent epinasty, a downward bending of the petioles, which are the slender stalks that attach the bracts to the stem.
Thursday, November 12, 2009
Like other non-food items, poinsettia plants are not edible and are not intended to be eaten. Poinsettias are a member of the Euphorbiaceae family of plants. Other economically important species in this family include: The cultivated rubber tree Hevea brasiliensis, Manioc or cassava (Manihot), and Castor bean (Ricinus). With its close genetic ties to the rubber tree, which is where natural latex is derived, those who are sensitive may also be sensitive to the latex from poinsettias. If eaten, parts of all plants may cause varying degrees of discomfort, but not death. Keep plants out of reach of small children.
Although commonly assumed to be poisonous to animals, Poinsettia plants are not toxic to household pets unless the leaves and bracts are eaten in very large quantities. Some cats that chew on the leaves may salivate and can vomit if the leaves are swallowed. Since cats and puppies frequently chew on new plants introduced to the home, it is prudent to place the plants out of reach!
So have no fear and go buy a poinsettia for your home and for your friends and relatives.
A sustainable food supply appears to be the new catch phrase for agriculture in the 21st century. And the concept of locally grown foods is often translated by many as a sustainable practice. Locally grown foods are typically said to require less fuel, thus having lower carbon footprint. The idea of eating only locally grown foods has become so trendy that now we have a word to describe the practice, "locavore."
To be a locovore, the challenge and adventure is finding foods from within a determined radius from home. The practice of eating locally can create a greater connection between consumers and their food sources and support the local economy. This movement is strong and many see an opportunity for new enterprises or a new way of surviving a troubled economy.
In Europe, where people have been stacked on top of each other for generations, land for local production is not easily available nor cheap. To replace the need for large expanses for food production, farmers use modern technologies. These include highly automated greenhouses as well as multi-level greenhouse structures. In our down-turned economy and with the drive for local foods, many are considering many technologies for local food production.
Sounds great, doesn't it? Well many seem to think so. So many that I am getting several inquiries on how to start a business. Where are they seeing this? Many are curious after reading media releases about those whom are constructing new projects or perhaps they just returned from EPCOT at Disney World in Orlando, Florida. The Land Pavilion has a grand display of intensive agricultural practices. Yet, are they sustainable?
So let's look at some facts. Below is a table that lays out an analysis for the production of lettuce in a greenhouse that is 3,072 square feet in size. These data were generated based on typical production yielding 59,000 heads (5 ounces) of lettuce per year with a market value of $1.10 per head, farm gate.
|Per Square Foot|
Here you can see that it is possible to make money on lettuce production in a greenhouse, providing you can maintain a sustainable price structure and consistent clientele.
Now let's add the fish. Based on several web sites that promote aquaponic production using tilapia (Nile tilapia, or Oreochromis niloticus), I am going to estimate that one can expect to yield about 0.75 pounds of fish per square foot of greenhouse space per year. For the greenhouse described above, this equates to about 2,275 pounds of fish per year. In 2004, the USDA valued tilapia at $1.72 per pound, farm gate, which equates to $3,913 per year in gross value. Rembember, this is for fish in the greenhouse, not the headhouse.
The greenhouse described in this scenario if built for lettuce, would cost about $23,000 or $7.55 per square foot to build. A kit ready system based on a similar size greenhouse and fish production facility would cost about $41,000 or $13.40 per square foot. This equates to a 78% increased cost to build, which equates to a $8,200 per year cost of ownership (based on 20% of the initial costs).
The lettuce scenario includes all variable costs, such as labor, labels, tags, boxes, sales, etc. The aquaculture component does not as I don't have any ideas on what they may be. But based on these rough calculations, lettuce and tilapia grown together will cost about $89,000 per year to raise for a gross income of $68,800 per year. Or a net loss of more than $20,000 per year.
Arguments for aquaponics as published by the National Sustainable Agriculture Information Service is managed by the National Center for Appropriate Technology (NCAT) promote aquaponics serves as a model of sustainable food production by following certain principles:
- The waste products of one biological system serve as nutrients for a second biological system.
- The integration of fish and plants results in a polyculture that increases diversity and yields multiple products.
- Water is re-used through biological filtration and recirculation.
- Local food product ion provides access to healthy foods and enhances the local economy.
- Hydroponic growers view fish manured irrigation water as a source of organic fertilizer that enables plants to grow well.
- Fish farmers view hydroponics as a biofiltration method to facilitate intensive recirculating aquaculture.
- Greenhouse growers view aquaponics as a way to introduce organic hydroponic produce into the marketplace, since the only fertility input is fish feed and all of the nutrients pass through a biological process.
- Food-producing greenhouses—yielding two products from one production unit—are naturally appealing for niche marketing and green labeling.
- Aquaponics can enable the production of fresh vegetables and fish protein in arid regions and on water limited farms, since it is a water re-use system.
- Aquaponics is a working model of sustainable food production wherein plant and animal agriculture are integrated and recycling of nutrients and water filtration are linked.
- In addition to commercial application, aquaponics has become a popular training aid on integrated bio-systems with vocational agriculture programs and high school biology classes.
Thursday, October 01, 2009
Friday, September 11, 2009
Friday, August 28, 2009
At Colorado State University, we conducted poinsettia cultivar evaluations for 10 years. Our last year to conduct a trial was conducted in 2004 with 139 cultivars. (click here to see the report)
For the production year of 2009, we have decided to return to conducting this trial. We have 80 cutlivars that have been submitted to the trial by our cooperators. The cultivars are listed below.
Please consider following the trial through the production season. I will provide periodic updates with photographs. And as always, our thanks go out to our sponsors, including Welby Gardens of Denver who rooted many of the cuttings.
The CSU 2009 Poinsettia Open House date is currently scheduled for Tuesday 1 December 2009 at the W.D. Holley Plant Enironmental Research Center Greenhouses. The address is 630 West Lake Street in Fort Collins. (click here for a map)
|Premium Picaso Dark||6/24/2009||6/28/2009||Early||Compact||Early|
|Freedom Early Red||6/24/2009||6/28/2009||Early||Medium||Mid|
|Freedom Early White||6/24/2009||6/28/2009||Early||Medium||Mid|
|Prestige Early Red||6/24/2009||6/28/2009||Early||Medium||Mid|
|Winter Rose Early Red||6/24/2009||6/28/2009||Early||Compact||Early|
|Carousel dark red||6/24/2009||6/28/2009||Late||Compact||Mid|
|Cortez electric fire||6/24/2009||6/28/2009||Mid||Compact||Early|
|Orion early red||6/24/2009||6/28/2009||Early||Compact||Early|
|Sonora white glitter||6/24/2009||6/28/2009||Mid||Compact||Early|
|Christmas Angel Pink||7/4/2009||7/6/2009||Early||Medium||Mid|
|Christmas Angel White||7/4/2009||7/6/2009||Early||Medium||Mid|
|Christmas Feelings Cinnamon||7/4/2009||7/6/2009||Mid||Compact||Early|
|Christmas Feelings Merlot||7/4/2009||7/6/2009||Mid||Compact||Early|
|Christmas Feelings Pink||7/4/2009||7/6/2009||Mid||Compact||Early|
|Christmas Feelings Select||7/4/2009||7/6/2009||Late||Compact||Mid|
|Christmas Feelings White||7/4/2009||7/6/2009||Mid||Compact||Early|
|Merry Christmas Apricot||7/4/2009||7/6/2009||Early||Medium||Mid|
Thursday, August 20, 2009
Myrtle spurge or Euphorbia myrsinites, is a very popular plant for xeriscape gardens, but unfortunately it is also highly invasive and is rapidly expanding into sensitive ecosystems throughout the inner-mountain western states. Colorado and Utah have listed it on their "A" lists for noxious weeds. Teton County in Wyoming has done the same.
As you have already realized, Myrtle Spurge is toxic. Actually, it is the milky latex that is toxic. As with many members of the genus Euphorbia, there are diterpenoid euphporbol esters present that can cause severe skin and mucous membrane irritation. In fact, this is very similar to the allergic response to latex.
Over 90% of the natural rubber in latex is from the rubber tree, Hevea brasiliensis (not to be confused with the rubber plant used as house plant, which is Ficus elastica). Hevea brasiliensis is a member of the Euphorbiaceae family and linkages within the genera have beed documented relative to latex sensitivity.
This plant should be removed from your garden. Myrtle spurge reproduces by seed and is capable of projecting it's seed up to 15 feet. Therefore, destroy the plant and don't place it in the compost bin.
Take care with handling the plant material, especially if you are latex sensitive. Where vinyl gloves and discard. You should also immediately launder your clothing.
Oh, and by the way, you can probably just pick off the caterpillars or apply a BT-based insecticide, which is safe to you and your pets. Here are some links that may assist you:
Wednesday, August 19, 2009
Tuesday, August 11, 2009
Thursday, July 23, 2009
So energy conservation may be the answer and it may be easier than you think.
The very first greenhouse that I worked in was at the University of Nebraska in Lincoln back in the late 1970s. It was a brand new IBG fiberglass reinforced plastic greenhouse with pad and fan cooling. It was beautiful. Yet, it needed to be shaded in the summer. So every spring, we attached shade cloth to the outside and removed it every fall. It was a pain, but it did keep the greenhouse cool.
So now let's jump to the 21st century and talk about retractable shade curtains. Retractable shade curtains in the greenhouse are not new, not innovative, and are really pretty common. But, do YOU have them in YOUR greenhouse? I'll bet not and you probably think that they are too expensive to install.
Yes, they can be a pain to install in an existing greenhouse as you will have to re-think all that stuff you have in the gable, but they are easy to install during new construction.
So why install retractable shade curtains?
Retractable shade curtains do effectively keep the summer temperatures down in your greenhouse. This extends your seasons very well (unless you are one of those growers who just takes the summer off for fishing). Retractable shade curtains also are very effective in cutting your fuel costs. Yet, why do not more growers use them? Are they really too expensive?
Up to 85% of the heat loss from a greenhouse occurs during the night. Thermal blankets can be a cost efficient investment. Retractable shade curtain manufacturers claim a return on investment at between 2 to 3 years. Installation makes sense to me.
About 10 years ago, at Colorado State University, we built some new greenhouse facilities to which we included retractable shade curtains. Each gutter connected greenhouse has a single layer polycarbonate roof with triple layer polycarbonate side and end walls. The heating system uses hot water circulated through the floor and through unit heaters. The environment is controlled by a Wadsworth EnviroSTEP controller. They are nice greenhouses.
So to determine what the actual savings in a greenhouse with retractable shade curtains, one of my graduate students, Drew Miller, began a project to evaluate heating efficiency during cold winter evenings. He used two identical interior greenhouse sections, to which he disabled the floor heating system. The hot water unit heaters were the only source of heat. Both greenhouses had retractable shade curtains.
To determine the energy demand in each greenhouse, we used the switch logs from the environmental control system, which recorded the on time of the unit heaters. The shade curtains on one house were closed at sunset and the other left open. This study was conducted over several evenings and the houses were alternated to disallow for any random differences between the environments.
At the conclusion of the study, we struggled with what to do with the data. We finally derived an evaluation to compare the two conditions, curtains closed and curtains open. We determined what is known as heating degree day hours, which we derived from heating degree days.
Heating degree days in a season are derived by summing the difference between the average outdoor temperatures above a base (e.g., 65°F) each 24 hours and the base temperature. Heating degree hours (equal to heating degree days x 24) are used in computing seasonal energy flows in a building due to both conduction and convection.
We then plotted the cummulative heater run time in hours against the cummulative heating degree hours for the individual study evenings.
When the shade curtains were left open, heating began at less than 25 heating degree hours.
So what is the savings? At 436 heating degree hours, the greenhouse with the shad curtains open required 2.69 hours of heater time and the greenhouse with shade curtains closed required 0.295 hours of heater time. This resulted in a savings of 2.39 hours of heater time.
The unit heaters in each greenhouse are designed to ouput 250,000 Btu/hr. With this assumption, the greenhouse with open curtains required 672,500 Btus of fuel per evening and the greenhouse with closed shade curtains required 73,750 Btus of fuel.
With natural gas fuel prices projected to be at $11.63 per dekatherm, this will calculate to be a cost savings of $6.96 each evening. And this was for a greenhouse section measuring only 240 square feet.
You can't afford shade curtains? You can not afford to not install shade curtains.
Wednesday, July 15, 2009
There has been a great deal of chatter among the public, landscape and horticulture professionals, and university faculty about these observed outbreaks. To clear up some mis-conceptions and provide the facts, Dr. Whitney Cranshaw,Colorado State University Extension Entomologist has provided the following explanation.
In parts of eastern Colorado extremely large numbers of lady beetles are being observed. Their numbers even prompted a June 18, 2009 note on the front page of the Pueblo Chieftain, and the southeastern counties appear to presently (June 19, 2009) have the highest numbers of lady beetles.
This is the result of previously high aphid populations on a wide variety of plants. The lady beetles develop feeding on the aphids. Aphid populations often spike in springs when there is a prolonged period of cool, wet weather. Some reasons for this include:
- Succulent new plant growth, promoted by rains and favorable temperatures, provides host plant conditions on which many kinds of aphids thrive;
- Rainfalls wash off the honeydew that aphids excrete, which is used by lady beetles as a supplementary food and a means to locate their aphid prey.
- Heavy rain falls may also dislodge some of the predators.
- Cool temperature retard the development of predators in relation to the aphids.
Although all insects are “cold-blooded” and develop in relation to temperature, the predatory insects usually have a higher base temperature requirement for activity. That means that cool temperatures slow down the predators quite a bit more than their aphid prey, allowing the aphid populations to largely escape predation and their numbers quickly soar.
Aphids can occur on a very wide variety of plants. Indeed it is hard to find any plant species that does not support one or more of the 350+ species of aphids that occur in Colorado. Oaks, lindens, walnuts, poplars, Norway maple, and most stone fruits are among the trees that often support large numbers of aphids. Spirea, roses, and many flowers can be common aphid hosts in spring. Weeds may now have large numbers of aphids, such as Canada thistle. Furthermore there are a great many native plants where aphids may be abundant; sage is currently supporting tremendous numbers of aphids - and developing lady beetles - in southeastern Colorado.
Ultimately, the predators do catch up. And because large numbers of aphids are present, large numbers of lady beetles are then produced. In the case of many areas this year, truly extraordinarily large numbers of lady beetles.
The most common species of lady beetle presently associated with the spring aphid bloom, by far, is the convergent lady beetle (Hippodamia convergens). A distant second is the seven-spotted lady beetle (Coccinella septempunctata). Green lacewings are also common predators consuming aphids at this time.Convergent lady beetle - Hippodamia convergens Guerin-Meneville. Photo courtesy of Whitney Cranshaw, Colorado State University, Bugwood.orgSevenspotted lady beetle - Coccinella septempunctata (Linnaeus). Photo Courtesy of Frank Peairs, Colorado State University, Bugwood.org
What will happen next? Lady beetles are general predators, although aphids are their preferred host. With the large numbers of lady beetles present they should largely annihilate most every aphid over the next few weeks. They will also incidentally consume some mites, scale insects and perhaps some eggs and young stages of caterpillars and leaf beetles. These types of insects may also be suppressed.
But soon there will not be enough food for the lady beetles to continue to sustain themselves and reproduce. So they will then likely “check out” out for the year. At some point every season lady beetles go into a condition known as diapause where they stop reproduction and slow metabolism. It is in this diapause condition that the insects survive winter. So most of the lady beetles, at least most of the convergent lady beetles, may decide to call it quits for the season and go into their winter dormancy earlier than normal, perhaps by mid-July.
The convergent lady beetle is the species that does migrate to the high country for the “off-season”. Hikers may see masses of these lady beetles near prominent points in the foothills and mountains along the Front Range during summer and early fall.
Of course, if the predators largely vacate, that may again open up a late season opportunity for the aphids to rebound. But so much can occur between now and then for this to be very predictable.Two Colorado State University Extension Fact Sheets that may be useful references are 5.594 Lady Beetles and 5.511 Aphids on Shade Trees and Ornamentals.
Friday, July 10, 2009
We all have seen those landscapes that attempt to conserve water. You know the one, that one with red rock or mulch with no turf. Or worse yet, artificial turf. Not only do these landscapes look tacky, but what of the energy load on your home?
So does the turf or flowering plants in your landscape impact the temperature in your own little microclimate? Well duh, which would you like to walk on, a freshly mown Kentucky bluegrass lawn or the shopping center asphalt? Urban centers always have a higher temperature than rural or suburban areas. This is due to the lack of trees and turf. So want to reduce the temperature and cool down your location? Then plant some plants.
A few years back and after a severe period of drought in Colorado, we conducted some trials on bedding plants and how they responded to decreasing levels of irrigation. What we learned was tha if you establish your plants well, little irrigation is required for a quality display. We also noted that the plants that did well under low irrigation also had lower leaf temperatures.
Plants, when well-watered, transpire water in order to deliver nutrients from the soil to the foliage and to keep the plants cool. They are the original evaporative cooling system. As a follow-up to that study, we conducted a trial where we decided to compare plants and plant color to determinine any cooling effects. Bluegrass is the coolest when well watered, which will reduce the temperatures of the immediate vicinity.
We also decided to look at flower color as well. We compared a dark flowered petunia to a light flowered petunia and we found that lighter colored blooms also help to keep the plant cool as well. This impact is most apparent when the plants are not irrigated.
Thursday, June 25, 2009
Anyway, at first glance I thought it some form of beetle and grabbed it to show my boys. This is my typical action while trying to ease the fears of my entomophobic teenager. On closer observation, I noted that it was not a beetle and at that single instany, it stabbed me fairly deeply with a surprising level of pain. Needless to say, that poor creature met a quick demise on the bottom of my shoe.
Not being an entomologist and not knowing many of the insects outside of what we find in greenhouses, I decided to determine exactly what we had found in the house. Of course, my boys were convinced that I was going to die. They watch entirely too many science fiction movies.
Just prior to retiring our uninvited guest, I did make a quick guess that what we had was a type of assassin bug, which is of the order Hemiptera (true bugs) and the family Reduviidae (Assassin Bugs). These carnivorous bugs use their long rostrum to inject lethal saliva that liquefies the internal organs of their prey and then they draw out yummy juices. In many parts of the world, a species known as masked hunters may feed on cockroaches and/or bedbugs and are raised as pets or for insect control. Some of these species are haematophagous (they feed on blood) such Triatoma spp. They are known as kissing bugs and have a habit of biting people on their lips and eyelids while sleeping. Species found in Central and South America vector Chagas disease (American trypanosomiasis). After telling this to my boys, they were ready to carry me to the emergency room (now I WAS afraid, my 16-year old does not even have his learner's permit).
So what bit me? After consultation with Dr. Frank Peairs and Dr. Whitney Cranshaw, Extension Entomologists at Colorado State University, we determined that what bit me was a Western Masked Hunter, Reduvius personatus. They are valuable members of our environment and gardens by hunting down and consuming many plant pests.
Reduvius personatus (Linnaeus) Adult
Photo by Joseph Berger, Bugwood.org
Reduvius personatus (Linnaeus)
Whitney Cranshaw, Colorado State University, Bugwood.org
Why was this bug in my house? The door was open. Are these bugs dangerous? Only to other arthropods, the clumsy, and me. Do they make good house guests? Not really and we certainly do not have any cockroaches at my house for them to feed. Are they good for the garden? Absolutely!! They may appear to be slow and non-aggressive, but they love to eat those that love to eat our favorite plants. Back off on your pesticides to encourage more predatory insects and mites.
Now back to my original intent, which was to show my boys more about our world by catching and observing creatures that we discover around our house. I had hoped to reduce my son’s entomophobic fears. This time I obviously failed and he gave me a strong, “I told you not to touch it!” Will I do it again? Of course, after all I am a professor and the son of a professor (I learned to roll my eyes a long time ago). Have I done it before? Yep, and to prove it, I have scars on my ear from a mother mockingbird defending her nest in Mississippi after realizing that her broken wing trick was not working (the neighbor kids whom I was trying to teach never returned to my yard).
Thursday, May 14, 2009
Of course, just like your annual check-up with your physician, the more tests the better. But just like your physician, nothing is free. So what can you test for on-site to save some dollars while being able to monitor your water quality in the greenhouse?
With the correct instruments and test kits you can test for many conditions on-site, including Alkalinity, salinity, pH, and sanitation. The next few blog postings, I will be covering techniques that you can use at your own greenhouse operation. As always, these on-site tests do not replace laboratory testing, but are a supplement. For determining the sodium absorption ratio (SAR), specific ion concentrations and solids, you still must use a laboratory.
One of the first things that a greenhouse grower needs to know about their water is the alkalinity. Alkalinity is defined as the capacity of water to neutralize acids. Anions typically found in water are bicarbonate (HCO3-) from dissolved salts such as calcium bicarbonate (Ca(HCO3)2), sodium bicarbonate (NaHCO3), and magnesium bicarbonate Mg(HCO3)2); and carbonate (CO3--) from dissolved salts such as calcium carbonate (CaCO3).
Alkalinity is not be confused with the term alkaline, which is where the pH is greater than 7. Laboratories often report alkalinity as a calcium carbonate equivalent, using milligrams per liter (ppm) of calcium carbonate. Some laboratories will report carbonates in molar values (meq/L).
The key to alkalinity issues is information and how it will impact your greenhouse production. For most greenhouse crops, an alkalinity from 40-120 ppm CaCO3 is safe. About 40% of U.S. irrigation water is greater than 200 ppm and 18% of U.S. irrigation water is less than 40 ppm. when the alkalinity of your irrigation water is high, it may raise the pH of your soil medium over time making some nutrients less available. To compound this issue, the smaller the soil medium volume, the more rapid the change. Therefore, plug production requires water with low alkalinity. The key is to adapt your nutrient management practices to your water source.
Acid injection is a convenient means to neutralize alkalinity in irrigation water. Sulfuric acid is the least expensive followed by nitric, phosphoric, and citric.
Most growers use sulfuric acid, but some use nitric, which may fume. Phosphoric is often expensive and may disrupt the phosphate balance of your fertility program. Citric acid is a possibility when an inexpensive source is available.
The next question to ask is how much acid should be injected to neutralize the alkalinity? Before that question is asked, first you must determine the alkalinity in your water. Of course, the best means is to send your water to a laboratory for testing, but there are inexpensive test kits that are quite good. The kit below is manufactured by HACH Company of Loveland, Colo. HACH manufactures analytical instruments and reagents used to test water quality1. Many of them are inexpensive and very easy to use. This Alkalinity Test Kit is currently priced at $37.89 for approximately 100 tests. That is less than 40 cents per test and you can not buy a cup of coffee for that. It is accurate within 5 ppm.
This test kit identifies the presence of alkalinity in irrigation water through titration with sulfuric acid. The colorimetric reagents are phenolphthalein and bromocresol green-methyl red. It is actually a fun test to conduct with kids as the color changes with pH.
An excellent resource for greenhouse growers for managing alkalinity was written by Dr. Doug Bailey while he was at North Carolina State University - ALKALINITY CONTROL FOR IRRIGATION WATER USED IN GREENHOUSES. This publication is easy to understand with specific recommendations. There are many more publications available on the NCSU Floriculture Science web site.
1The information contained herein is provided as a public service with the understanding that Colorado State University makes no warranties, either expressed or implied, concerning the accuracy, completeness, reliability, or suitability of the information. Nor does Colorado State University warrant that the use of this information is free of any claims of copyright infringement. Colorado State University do not endorse any commercial providers or their products.
Monday, April 27, 2009
Responding to the drought in Colorado during 2002, Dr. David Hartley, Emeritus W.D. Holley Chair of Floriculture, and I collaborated with Yvette Henson, then a master of science graduate student. Yvette conducted a study on herbaceous annual ornamentals and their performance at decreasing levels of irrigation. Yvette's study was conducted to determine water requirements and quantify the growth, visual quality and health of 17 popular species of bedding plants grown outdoors under Colorado conditions compared to Kentucky bluegrass.
The objectives of this research were to provide information on minimum irrigation requirements for annual herbaceous ornamental plants to be used by landscape professionals and eventually homeowners. This study was establsihed outdoors for ten weeks during the summer of 2003 in Fort Collins, Colorado. Plants were irrigated at 100% of the reference evapotranspiration (ET) (amount required to maintain Kentucky bluegrass in an optimum condition) for two weeks followed by eight weeks at five irrigation levels, 0%, 25%, 50%, 75% and 100% ET. Daily weather data (temperature, solar radiation, wind speed and relative humidity) were collected from a local weather station, which were used to calculate location-specific ET.
The species studied were: Antirrhinum, Begonia, Catharanthus, Dianthus, Impatiens, Lobelia, Lobularia, Pelargonium, Petunia, Poa, Rudbeckia, Salvia, Senecio, Tagetes erecta, Tagetes patula, Glandularia, Viola, and Zinnia. Realizing that with a diverse collection of bedding plant species with differing growth habits, percent cover may not accurately assess plant growth when using only one plant spacing. To accommodate for that issue, the percent change in cover was also determined. The difference between the final percent cover and the initial percent cover was analyzed as percent change.
Eight weeks after the imposed irrigation treatment levels, a visual rating of 3 indicated good plant growth with minimal signs of drought stress, insect and/or disease damage. The plants were fairly uniform and vigorous in growth and flowering. Visual plant ratings were averaged for each species within each treatment to determine the lowest irrigation level where each species still maintained acceptable visual quality. Each species was rated on a scale of 0 to 5, where: 0 indicated dead or mostly dead plants; 1 indicated poor or extensive wilting, curling, burning or discoloring, insect and/or disease damage to plants.; 2 indicated fair to moderate signs of stress, insect and/or disease damage; 3 indicated good plant growth with minimal signs of stress, insect and/or disease damage; 4 indicated very good plant growth with no signs of stress, insects or disease; and 5 indicated excellent plant growth with no signs of stress, insects or disease. An evaluation score of 3 or above at any level was used to determine the lowest irrigation level where growth and appearance were acceptable.
Begonia, Lobelia, and Viola grew well with a minimum of 50% or more ET based on Kentucky bluegrass. Impatiens grew well only with 100% ET. Antirrhinum, Dianthus, Lobularia, and Pelargonium performed well with 25-50% ET. Catharanthus, Rudbeckia, Senecio, Tagetes erecta and Tagetes patula, Zinnia, and Salvia, which are adapted to mid-summer heat and low water, performed well with 0-25% ET. Species considered to be heat or drought tolerant, Petunia and Glandularia, required little or no irrigation.
The bedding plant species evaluated in this study that required 25% or less ET are well adapted for low water landscape installations.
Do we need all that water for quality bedding plants? Obviously no, but establishment and correct species selection is very important.
See the complete research report as published in the American Society for Horticultural Sciences HortScience.
Yvette Henson now works for Colorado State University Extension in San Miguel County. This research was sponsored by the Colorado Floriculture Foundation and Welby Gardens of Denver, Colorado.
Friday, April 17, 2009
Severe droughts often trigger municipal watering bans and plant restrictions. How the greenhouse and nursery industry responds to these regulations requires an integrated approach requiring participating from all involved including growers, landscapers, property owners, water providers, and local government. The Green Industries of Colorado managed to assist growers, retailers, and contractors to survive the 2002 drought through a proactive establishment of Best Management Practices (BMPs) developed in collaboration with all parties.
There are a lot of facts that are often not published when it comes to water use and water consumption. No one likes to see sprinkler systems in poor repair running water everywhere excpet where intended. Landscape irrigation is very visible to the public, but is that where our water goes?
The U.S. Geological Service (USGS) last published an estimate of water use in the United States. The authors determined that the U.S. uses 408,000,000 per day. They estimated that 323,000,000 per day is from surface supplies. The largest single component (48%) of that water use is from the generation of electricity from thermoelectric generating stations (Fig. 1). Second is that from general agriculture (35%), which includes irrigated crops as sell as livestock operations.
Public, domestic, industrial, and mining consume only 16% of the U.S. water. Of that only 46,890,000 gal/day include public and domestic water use. Outdoor water use is estimated to be between 40 and 60% of that use, which ranges from 18,756,000 to 28,134,000 gallons per day or 8.7% of all water used in the U.S.
During times of drought, municipalities often impose watering restrictions. These may range from voluntary restrictions to required watering schedules. Many of these restrictions may be draconian to the point where they may impact the landscape and related green industries.
What is the impact of water restrictions? Do they serve the purpose for which intended? Are those restrictions developed from science or are they developed by bureaucrats operating from a sense of control rather than the impacts of their actions on all effected.
During the late summer of 2002, Colorado was in the midst of coping with a devastating drought and dwindling water supplies. By mid-summer, most municipal water providers implemented some form of watering restrictions and the city of Fort Collins was not different. They implemented an even and odd address irrigation pattern with an attempt to ease water demands.
After receiving a very revealing water bill, a Fort Collins area manufactured home park manager contacted me wondering why the park's water use was so high (Fig. 2).
It is important to note some demographics of this 27 acre park. The park is 100% owner occupied and of those residents, 80% are retired. To maintain a quality environment, the park provides water with an expectation that the residents keep the grass green.
Looking at the months of May and into June 2002, you can see that the water use was on the decrease. During this period water restrictions were voluntary, but on 27 July, mandatory restrictions were enforced. It was at this point that water use increased to a level greater than the year prior.
So why did the water use increase? It is simple human nature. When it is your turn to use a resource, you will use it whether you need it or not. So goes the fallacy of mandatory irrigation scheduling.
The spring planting season is upon us and with any luck, this will be a great year for the green industries. With the economic downturn, many will be staying home and will want to have their own private oasis. Promote good gardening, promote good plants, and recommend proper watering practices.
Xeriscape not zeroscape.
For a commercial greenhouse operation to remain sustainable, irrigation practices should be modified to better manage limited water resources as well as manage non-point source pollution issues. We have the technologies to do this in many forms, including waste water capture and recycling water in greenhouses, yet acceptance is low due to the costs of implementation as well as inadequate technical information.
Early in my career at Colorado State University, I worked with Sean Moody, a graduate student who completed a study on growing poinsettias using strategies to reduce leachate and. His study used two cultivars, Eckespoint Freedom Red and Gutbier V- 17 Angelika Red (provided by the Paul Ecke Ranch), which were subjected to three irrigation strategies: 10% leach, ebb-and-flood and no leach or pulse, at two constant liquid feed fertilizer rates, 150 and 300 ppm N from 15-5-15 Cal-Mag Plus from O.M. Scott.
Heavy leaching of water and fertilizer is not an acceptable and sustainable production practice. Most fertilizer recommendations for poinsettias suggest 200 to 400 mg·L-1 nitrogen (N) applied at every irrigation. Ebb-and-flood (Fig. 1) is one alternative to heavy leaching, but there is a high investment cost in equipment and maintenance. When using ebb-and-flood or pulse irrigation, which is accomplished with small frequent irrigation applications applied to saturate the media with no leaching, fertilizer concentrations must be reduced to avoid high electrical salt build up in the root-zone medium.
Pulse irrigation is a modification of a conventional irrigation system that applies water at reduced volume with little or no leach. Pulse irrigation strategies can be designed using conventional micro-tube irrigation emitters. However, the irrigation controller must be sophisticated enough to provide precision control in fractions of a minute. Additionally, pressure compensated emitters must be used to ensure that each pot receives the exact same volume of irrigation solution from one end of the bench to another.
The study was conducted from week 34 (transplant) through week 47 (anthesis) in a FRP-glazed greenhouse. The plants were grown in 6-inch azalea pots using Premier Pro-Mix HP. All plants on the ebb-and-flood benches were irrigated when approximately 2.5 cm of moist media remained at the bottom of the pot. The irrigation solution was pumped from the holding tank to the containers bench top, held for 10 min., and drained back to the tank for later recirculation. Fertilizer solution was added to the tanks when the level dropped below half to maintain enough solution to sufficiently flood the benches. Pulse and 10% leach strategies were calibrated to where the leachate was equal to zero and 10% of applied solution, respectively. Pulse irrigation was conducted once daily until week 40 and twice daily subsequently at 900 and 1300 MDT study. The 10% leach plants were irrigated daily.
Leaching of containers is a common practice to prevent high salt build-up in the medium of greenhouse crops. The salt levels are typically measured by determining the electrical conductivity (EC) of the root-zone medium. For this study, from three horizontal sections of the media, top, middle and bottom, a saturated paste extract for each irrigation treatment was collected. The EC was then determined from those sections.
'Angelika Red' dry weight, height, and width were greater than 'Freedom Red' as one would expect. Fertilizer rates did affect plant growth in this study, thus those data were pooled. Ebb-and-flood irrigation only slightly reduced plant width of 'Freedom Red' (Fig. 2) and pulse irrigation slightly reduced plant width of 'Angelika Red' (Fig. 3). Other studies have reported that sub-irrigation treatment or no leaching yields poinsettia plants of similar size.
Irrigating to 10% leach resulted in the lowest EC values for poinsettias, followed by pulse, while ebb-and-flood had the highest EC values (Fig. 4). The top medium layer had higher EC values for all three irrigation strategies, which was expected due to the wicking of water to the surface of the medium. The EC value of the top layer from the ebb-and-flood irrigation at 300 mg·L-1 N resulted in an EC value 1.5 times greater than that normally thought to be injurious to plant growth (>8 mS·cm-1). Even the middle and bottom layers of the containers from the ebb-and-flood irrigation at 300 mg·L-1 N had EC values greater than 4 mS·cm-1, which is considered to be too high, i.e. 4-8 mS·cm-1. At 150 mg·L-1 N, the top layer for ebb-and-flood as well as pulse irrigation had a relatively high EC value of approximately 4 mS·cm-1 or greater (Fig. 4), but all other EC values for the other layers of the container were within acceptable levels, between 2-4 mS·cm-1. The EC values for the 10% leach irrigation at 150 mg·L-1 indicated low fertility; whereas, at 300 mg·L-1 was adequate for good plant growth.
Poinsettias of acceptable quality may be successfully grown using ebb-and-flood or pulse irrigation strategies at constant liquid feed fertilizer rates of 150 mg·L-1 nitrogen (N). No leach irrigation practices in excess of 300 mg·L-1 N may result in excessively high EC values resulting in poor plant growth. These practices effectively reduce runoff as and can be adopted to reduce the non-point source pollution risk of a greenhouse.
To see Sean's thesis, click here.
Sean now works for Landscape Designs by Ellison