It is known as Fibonacci numbers and named for an Italian mathematician that lived between 1170-1220AD. The sequence is generated by starting with 1 and adding 1 to make 2; 2 is added to the last number (1) to make 3; 3 is added to the last number (2) to make 5, etc. This sequence is commonly seen in plants in the growth and development of leaves and other tissues. For instance, looking at the base of pinecones, the number of swirls of scales radiating from the center differ based on the direction (clockwise versus counterclockwise). The two numbers of swirls are typically two adjacent Fibonacci numbers (the red pine cone pictured has 5 swirls one direction and 8 the other). Cones of different pine species can have different adjacent pairs of Fibonacci numbers (e.g. Eastern white pine has 3 and 5). Different pine species also have different characteristic numbers of needles grouped together in their fascicles (typically 2, 3, or 5). Fibonacci numbers can also be observed looking at the direction and swirls of scales on pineapples, arrangement of florets in composite flowers (like sunflowers) and cole crops (like broccoli), and spine arrangement on many cacti. The spiraling sequence of leaves around the stems of many plants have numerical relationships between leaf number and number of rotations around the stem consistent with Fibonacci numbers. What other growth relationships in plants or animals can you find that follow Fibonacci numbers?
Here’s something you might not know. Though they are only sold during the holiday season, poinsettias repeatedly rank as the number-one selling potted flowering plant in America with more than 70 million sold annually. Not bad for a desert-dwelling plant that had nothing to do with Thanksgiving or Christmas until the 1920s.
That’s right. Poinsettias are now an indispensible part of our holiday season through sheer marketing genius. The story began with Joel Roberts Poinsett, an amateur botanist and U.S. ambassador to Mexico from 1825 to 1829. He spotted the plant growing wild in Mexico, where it can reach heights of over 10 feet before blooming, and decided to ship a few of them back to his home in South Carolina. Over the next few years, he propagated the plants in his own hothouses and sent some to his friends and to botanical gardens. By 1833, the first “poinsettias” were on sale in local nurseries.
Still, it wasn’t until the 1920s that California agricultural entrepreneur Albert Ecke and his son Paul saw the unique plant’s holiday potential. By this time, poinsettias were thriving in California’s warm climate and father and son had noticed that the plant did not have traditional blooms. Instead, poinsettias’ leaves, which are called bracts, turn colors when the days start to get shorter. With their brilliant red color peaking in early winter, the Eckes figured the public would fall in love with the idea of poinsettias for the holidays. And they were right.
Today, the Paul Ecke Ranch, in Encinitas, Calif., is the largest breeder of poinsettias in the world. They are also the biggest supplier of poinsettia cuttings to commercial growers in the United States. It’s a big commitment to grow poinsettias from cuttings. (Seeds can’t be counted on to produce offspring that look exactly like their parents.) Twin Cities-based Bachman’s and Gertens, for example, each successfully grow more than 90,000 poinsettias each year.
To have them ready for the holidays the cuttings, which are only about two-inches tall, must be started in greenhouses in June. From then on, they are fussed over constantly to ensure they get just the right amount of water and fertilizer, that the temperature is right, and that they’re pest- and disease-free right up until show time in November.
What does this level of care entail? Louis Gerten, co-owner of Gertens, says that for the first four weeks after the cuttings are put into their small pots, they are misted every 15 minutes by a machine that continually passes slowly overhead. Over at Bachman’s, Jack Geyen, who has been growing poinsettias for the company for more than two decades, personally walks the aisles of their Lakeville greenhouse several times a day making sure everything is just right. Though he’s had few problems over the years, Geyen says it’s always a great relief when all the poinsettias have been shepherded through another season.
Poinsettias just keep getting better
Though red remains the most popular poinsettia color, breeding programs launched in the 1960s by the USDA and a few private companies, including the Paul Ecke Ranch, have dramatically changed the plant over time. Today’s poinsettias are bred to be stronger and last much longer than their ancestors did. Genetically, they are also shorter and a little stockier, which is good news for greenhouse growers who previously had to strictly control temperatures to keep plants from getting too leggy.
In addition to creating heartier varieties that are easily shipped as cuttings, breeding programs have produced plants that include varieties with blooms of white, cream, pink, maroon, orange, salmon and marbled blends. Green leaves beneath the blooming bracts are now light or dark, depending on the variety and both blooming and green leaves can be large or small, smooth or pillowy.
While new poinsettia varieties are introduced in trials every year, there are several recent standouts available this season.
Poinsettia Purchasing and Care Tips
Look for poinsettia plants that are:
Poinsettias are susceptible to chilling injury. This occurs when temperatures are between freezing and about 50F and results in wilting even though the soil is moist and if severe enough can lead to browning and death of the most exposed tissue. Make sure poinsettias are wrapped well at the store and kept warm on their way home.
Once you have your poinsettia home:
An ecological disturbance of growing concern, frequently facilitated by the horticulture industry, is the release of invasive species as ornamental plant s. Common buckthorn (Rhamnus cathartica), burning bush (Euonymus alatus), Norway maple (Acer platanoides), amur maple (Acer ginnala), Japanese barberry (Berberis thunbergii),butterfly bush (Buddleia davidii), common tansy (Tanacetum vulgare) and a host of other species are sold for their ornamental characteristics, and have escaped from controlled cultivation and thrive as invasive species. Some introductions outcompete and replace native plants, which not only alters the plant community but the entire ecosystem. In fact, over 85% of all woody invasive species were deliberately introduced and cultivated either as ornamentals or for other purposes (Li et al, 2006). Such exotic invaders have escaped cultivation and are now very difficult to control.
Many of these invasive species, such as common buckthorn, common tansy and butterfly bush have been designated noxious weeds in some states and counties, which can make the control of these species by the government or landowner mandatory. Alternatively, invasive species may be found on “watch lists” that inform the public about the potential of these plants to escape cultivation (see web sites for the Minnesota Department of Natural Resources, http://www.dnr.state.mn.us/invasives/ or the Minnesota Invasive Species Advisory Council, http://www.mda.state.mn.us/plants/pestmanagement/misac/default.htm). Government regulation mandating control of a plant can have consequences for government, growers, consumers and landowners because of the great cost which is incurred as a result of mandatory removal. The removal of highly invasive plants often results in collateral damage to non-target species, which can lower natural genetic diversity at a site (i.e. seed banks of desirable plants are depleted and some desirable species are no longer present) and even leave a site vunerable to more invasions. Placement of plants on noxious weed lists leads to discontinued sale of the non-native invasive species. This adversely affects the ornamental horticulture industry because plant inventories must change by either reducing plant selection or requiring production of alternative plants.
For instance, Norway maple and Japanese barberry are prohibited in Massachusetts and they are being closely regulated in Connecticut. These plants also have redeeming qualities and are very valuable and popular crops in the horticulture industry. They provide over 7 million dollars to the Connecticut horticulture industry alone (Heffernan, 2004). Prohibition of these crops would be very detrimental to the horticulture industry and consumers would lose options of plant choices. There is, therefore, a need to develop less invasive, high value ornamental crops. The development of these strategies is a main focus of our research at the University of Minnesota.
A strategy proposed for the development of less invasive varieties is gamma radiation mutagenesis breeding. Radiation can break or otherwise alter DNA and lead to permanent genetic changes and new traits. Mutagenesis breeding can be performed by treating plants with Gamma-rays Gamma-ray mutagenesis of plants is used extensively in agronomy and horticulture to induce changes in plants to create diversity from which plant breeders can select new varieties (Broertjes and Harten, 1978). Historically, Gamma-ray and x-ray mutagenesis were extensively studied during the Cold War period in order to determine what impact a massive radiation fallout might have on plants and cropping systems (Moh and Smith, 1951). However, long before radiation-fallout studies took place, there were researchers using radiation as a method to induce change in apple trees (Stadler, 1930) and other horticultural and agronomic crops. It was not long before horticulturalists were routinely testing gamma radiation as a method to induce desirable changes such as increased disease resistance, compact growth habit, and fruit quality (Broertjes and Harten, 1978). Improvement in fruit set, fruit timing, dwarfness, seed number and yield has also been observed in some plants after radiation treatments (Predieri, 2001). One of the most common changes in a plant after radiation treatment is the loss of fertility and therefore loss of seed production. Loss of seed production can be advantageous to an ornamental crop as it can increase flowering (energy typically diverted to fruit development can be used to set more flowers) and flower longevity (successful pollination/fertilization often triggers a flower to begin to senesce and without this trigger flowers last longer) while preventing reseeding. Radiation was successfully used to produce sterile varieties of v erbena (Kanaya, et al 2008) and c hrysanthemum (Broertjes et al, 1984) for these reasons.
The induction of sterility would be valuable for many horticultural crops, especially those with invasive potential. We are testing radiation breeding for this purpose in several plants where there is known or potential risk of invasiveness. We are also developing strategies to genetically engineer sterility into invasive crops as a means to compliment our mutation breeding method. This is a long term strategy as many of these plants are long-lived perennials with long juvenile periods before they flower and set seed. Characterizing the plants we generate for such traits and eventually selecting and introducing cultivars with greatly reduced invasive potential will take several years. However, because invasiveness can have significant environmental and economic impacts, these efforts hold great promise to meet the goals of both meeting the horticulture industry’s need for plants with high consumer value and to protect the environment by combating invasiveness.
Broerjtes, C. and J. DeLong. 1984. Euphytica 33:433-434. Broertjes, C.and A.M.V. Harten. 1978. Application of mutation breeding methods in the improvement of vegetatively propagated crops. vol. 2. Elsevier Scientific Publishing Company, Amsterdam-Oxford-New York.
Heffernan, Bob. 2004. Economic Impact of Banning Plants on the Invasive List. A Report for the Connecticut Invasive Species Council.
Li, Yi, et al. 2004. Critical Reviews in Plant Sciences 23.5 (Sep. 2004): 381-389.
Moh, C.C.and L. Smith. 1951. An analysis of seedling mutants (spontaneous, tomic bomb-radiation, and X-ray induced) in barley and durum wheat. Vol. 36: 629-640.
Predieri, S. 2001. Plant Cell, Tissue and Organ Culture. 64: 185-210.
Smith, A.G.and N.O. Anderson. 2006. Engineered Sterility for Non-native Plant Invaders. In: J.A.T.d. Silva (ed.). Floriculture, Ornamental and Plant Biotechnology: Advances and Topical Issues. Global Science Books, London, UK.
Stadler, L.J. 1930. Journal of Heredity. 21: 3-19.
USDA. 2006. the PLANTS databasem version 3.5 (http://plants.usda.gov). Data compiled from various sources by Mark W. Skinner. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
Over the past couple of summers an unusual symptom has appeared on several Twin Cities lawns, primarily in several northern and western suburbs. Specific sites include several home lawns as well as a couple of townhouse locations. The symptom is particularly unusual in that is seems to be associated with mowing patterns. That is, those areas where the (riding) mower wheels have travelled, the grass appears to be green and healthy. Those areas that were under the mower deck but not driven over by mower wheels vary in color from light green to a yellow color on the leaf blades. Typically this symptom has shown up from late July through early September.
Upon closer inspection, those areas with the discolored grass between the wheel tracks were associated with many white cottony tufts about the size of an end of a cotton swab located on the lower half of the grass blade and down onto the sheath area. Initially, one might expect that these would be associated with various spiders in the lawn as they did appear like small spider egg cases. Where these insects are found, there can be dozens to a few hundred of these small cottony like structures in as little as one or two square feet of discolored turfgrass. When examining the wheel tracks where the grass is greener, there are few to none of the cottony structures present.
When the insects were examined more closely they were not easily identified. Finally, they were determined to be a type of soft scale (family Coccidae). It was puzzling as there are very few reports of any scale associated with Kentucky bluegrass. The Systematic Entomology Laboratory in Beltsville, Maryland identified them as Eriopeltis festucae, an insect commonly known as cottony grass scale.
This scale is relatively small, 1/8 - 3/8 inch long, and is covered by a white waxy material known as an ovisac which is secreted by older females to protect their eggs. Cottony grass scale bears a resemblance to cottony maple scale. In fact, one homeowner thought their cottony grass scale was cottony maple scale that had fallen to the ground.
Although cottony grass scale is apparently not common in the U.S., it is found in a variety of states. It has been reported in the literature from Virginia, Maine, New Jersey, Indiana, Illinois, North Dakota, South Dakota, Nebraska, Montana, Colorado, Nevada, and California. Additionally, it has also been sighted by entomologists in Iowa, New York, Maryland, and possibly Wisconsin, Rhode Island and Pennsylvania. It is also found in Nova Scotia and New Brunswick Canada. It is not clear what the history of this insect is in Minnesota. It has generally not been reported in the last 25 - 30 years (that anyone is specifically aware of) until the last couple of summers. A perusal of the Insect Museum in the Department of Entomology reveals a single collection of this insect collected from Ramsey County in 1922. It would seem at best to be a rare insect here.
There was one incidence reported of their presence during the summer of 2007 and several reported during the summer of 2008. In all cases the insect was associated with well maintained Kentucky bluegrass. ‘Well maintained’ means that the lawns were watered adequately and regularly fertilized. Mowing was also done on a regular basis with mowing heights ranging from about two to three inches. There does not appear to be any particular association with soil type as reports have come from both sandy as well as heavier clay soils. Also, the insects are more prevalent in sunny to very lightly shaded areas but not fully shaded areas. One of the reports indicated their sporadic presence on fine fescue. We don’t know about its ability to invade other grass species and cause similar symptoms.
How and when did it get here and does it survive our winters? What is its life cycle? Why the particular injury pattern seemingly associated with mower tire tracks? Those are all questions for which we have little information at this time. Cottony grass scale is reported to have two generations a year. It is not clear whether this is true in Minnesota. It overwinters as eggs underneath the white waxy material of its mother which presumably hatch in the spring (assuming they survive the winter). The immature scales are very small, pinkish, and without any covering. They would be inconspicuous in the turf in this stage and would only be noticeable later in the summer when they matured into adults and the females produce their ovisacs. Interestingly, scale crawlers were observed in late July at one of the sites.
In the site that was indentified in 2007, the lawn care provider had went back this summer (2008) to inspect the lawn and found no evidence, not even a trace, of these insects that had been so prevalent the summer before. On the other hand, it was also noted that one individual had experienced this pest (presumably) in 2006 and 2008 but no sign of its occurrence in 2007. So you can see that there is really scant information about what may be really going on with this insect.
So, how serious a pest is this? Like other scale insects, cottony grass scale has piercing-sucking mouthparts and feeds on the sap of grass blades. There can be yellowing and browning associated with their feeding. However, this feeding does not appear to affect the crown or cause any lasting damage to turf. Some people have objected to the presence of the insects themselves in their lawns and have viewed them as nuisances.
So what should you do if you have cottony grass scale in your lawn? Normal lawn care should be sufficient to counter act the effects of this insect. Treatment of this insect should not be necessary and is not recommended at this time.
If you believe you have cottony grass scale in your lawn, please contact one of the authors. If available, please send along pictures of the insects and damage you believe the insect has caused. You can contact Jeff Hahn at firstname.lastname@example.org and/or Bob Mugaas at email@example.com.
One way for avid Minnesota gardeners to fill the cold winter months is to grow herbs indoors. Herbs are typically easy to grow and can spice up winter meals. Those gardeners anxiously awaiting their first batch of pesto, however, may be disappointed this year. A fungal wilt disease of basil, known as Fusarium wilt, has been found on seed and in some potted basil plants in Minnesota nurseries this year.
Fusarium wilt is caused by the fungus Fusarium oxysporum f.sp. basilici. This fungus will only cause disease in basil (Ocimum basilicum). Infected basil plants often start out healthy. When the plant reaches 6-12 inches (about the time you are pulling out your pesto recipe) the plant’s growth slows down. Brown streaks may be seen on the stem and brown blotches develop on the leaves. As the disease progresses the plant wilts and curls over in a shepherd’s crook. Infected leaves often fall off prematurely. If the stem is cut open, brown streaks can be seen. In some cases pinkish orange spores can be found on infected stems. Susceptible varieties eventually die. Young plants expire quickly, while older plants may linger on awhile longer.
Unfortunately there is no treatment for infected basil plants. Fungicides are ineffective and although a few biological control organisms have been tested, none have reliably provided control. Infected plants should be removed immediately because spores from infected stems can move on air currents or splashing water to infect nearby basil plants.
Prevention is the only way to control Fusarium wilt of basil. Since the fungi can survive in soil, new sterile potting mix should be used for potted herbs. If the disease has been a problem in the past, make sure to sterilize pots in a 10% bleach solution before reusing them. Since the fungi can come in on infected seed, even the most sterile set up can still result in diseased plants. Several seed companies test basil seed for the presence of fusarium. What this means is that a large number of seeds from each seed lot are grown. If none of the seeds grow into an infected plant, than the whole seed lot is sold as ‘fusarium screened’. This does not guarantee that every seed will be free of the pathogen but the likelihood of ending up with healthy plants is improved. For now this is the best screening method available.
Probably the best option for gardeners is to use a variety that is tolerant or resistant to the disease. Many varieties of basil are available for gardeners to choose from, and although they can all become infected with Fusarium wilt, they vary greatly in how severely they are affected by the disease. Sweet basil is one of the most susceptible varieties. This is the variety commonly used in Italian cooking. Spicy Globe miniature basil is also very susceptible and will be quickly killed by the disease. Some varieties of purple basil or lemon basil seem to tolerate the disease. When tested, one variety of Lemon Basil (O. basilicum var. citriodorum) never showed symptoms like wilting or browning but was clearly stunted by the infection. ‘Nufar’ is a variety of sweet basil that is resistant to fusarium wilt. This variety originated from a few healthy plants found in the middle of a diseased field in Israel. The variety was tested and found to be genetically resistant to Fusarium wilt. It will grow into a healthy plant even in fungi infested soils. ‘Nufar’ is now commercially available in the United States through several seed companies.
If you are one of the millions of Americans who still treasure a fresh cut Christmas tree, a trip to your local tree lot or Christmas tree farm is probably on your calendar. In Minnesota, the selection of tree species and varieties you can choose from at a tree lot typically includes Scots pine, Norway (red) pine, white pine, white spruce, Colorado spruce, balsam fir, Canaan fir, and Fraser fir.
Scots pine (Pinus sylvestris) is the most widely distributed pine tree in the world, ranging from Norway and Scotland to Spain, western Asia, and into northeastern Siberia where it grows in areas with temperatures as low as -83o F. This species was introduced into the United States, probably in colonial times, from Europe. When planted in our landscapes, we know it as the picturesque pine tree with horizontal branches and orange bark in the upper portions of the tree. Scots pine can grow to 90 feet. Norway or red pine (Pinus resinosa) and eastern white pine (Pinus strobus) are native to the United States and to Minnesota. Norway pine ranges from Minnesota and Manitoba east to Pennsylvania and Newfoundland, grows 50-80 feet tall, and is easily recognized by the tufted arrangement of its needles and its flaky reddish brown bark. Eastern white pine, recognized by its soft-to-the touch needles, horizontal branching, and plume-like growth habit, grows from Manitoba south to Iowa and east to Newfoundland and Georgia and often reaches heights greater than 100 feet.
White spruce (Picea glauca), another Minnesota native, has one of the largest ranges of any North American conifer. It grows from Alaska to Labrador and from Idaho to Maryland. Slow-growing, pyramidal forms such as P. glauca ‘Densata’ (more commonly called Black Hills Spruce) are popular trees in our landscapes. Colorado spruce (Picea pungens) is native to the central and southern Rocky Mountains ranging from Wyoming and Idaho south through Utah, Arizona, New Mexico and Colorado. Needle color ranges from green to blue and 30-50 foot blue forms of this tree are frequently seen in our landscapes.
Balsam fir (Abies balsamea), Fraser fir (Abies fraseri), and Canaan fir (Abies balsamea var. phanerolepis) are three closely related firs that are among the most popular Christmas trees. Balsam fir is native in much of Canada and in the northern tier of states as far west as Minnesota in the United States. In our forests, it is a narrow tree with a spire-like crown and can grow up to 80 feet in height. Fraser fir or southern balsam fir has a much smaller native range, occurring only at elevations above 4500 feet in the southern Appalachian Mountains from southwest Virginia, through western North Carolina, and into eastern Tennessee.
Canaan fir has many similarities to both Fraser and balsam fir in growth and appearance and those similarities have led to a great deal of taxonomic confusion. In the early 1900’s, a variety of balsam fir having cone scales extending from the bracts was identified. Typical balsam fir cones have scales not extending from bracts so this new variety was named Abies balsamea var. phanerolepis (phanerolepis means conspicuous scales). The common names most often used for this tree are bracted balsam fir and Blue Ridge fir. Bracted balsam fir were found growing in the same types of sites as its close relatives balsam and Fraser fir and its growing range extends from Labrador to Ontario and from coastal Maine to the high mountains of Virginia and West Virginia. Some taxonomists suggested that all three of these firs were simply three varieties of Abies balsamea: A. balsamea var. balsamea, A. balsamea var. phanerolepis, and A. balsamea var. fraseri. Others thought that because bracted balsam fir had traits intermediate between balsam fir and Fraser fir, it should be listed as its own species A. intermedia. Neither of these classifications found widespread approval and now bracted balsam fir is considered a variety of balsam fir with the scientific name of A. balsamea var. phanerolepis.
So where does Canaan fir fit into this picture? Canaan fir is a bracted balsam fir (A. balsamea var. phanerolepis) from the southern part of the growing range with growth habits different from other bracted balsam fir. Several of the original trees with these growth traits were identified in the Canaan Valley of West Virginia, giving rise to the common name of Canaan fir. Today Canaan fir is considered a special “ecotype” of bracted balsam fir, whose unique characteristics developed as it adapted to its growing environment in the high mountains of West Virginia. Regardless of the taxonomic confusion surrounding these three firs, all of them are beautiful when grown as Christmas trees.
How are these forest and landscape trees transformed from 20- to 100-foot trees into the smaller, denser pyramidal forms that we can carry into our homes as Christmas trees? Two- to three- year old seedlings are planted by Christmas tree growers and are grown as a labor intensive farm crop. Transplanted seedlings are watered until they are fully established and like any other crop are weeded, fertilized, and sprayed for disease and insect pests during the 6 or more years needed to produce a Christmas tree. Annual shearing starts as trees reach three feet in height which shapes the trees, encourages denser branching, and creates a uniform fullness throughout the crowns. In autumn as temperatures drop, the needles of pines often pale so they are often “greened” or painted as they approach their harvest date. Harvested trees are mechanically shaken to remove dead needles in the interior of the tree followed by mechanical bailing for more efficient transport to tree lots.
As you choose between pine, spruce, and fir at the tree lot or farm, factors to consider include price, tree color and fragrance, branch stiffness, and needle softness, length, and retention. Scots pine is typically the most inexpensive of Christmas tree species while Colorado spruce and Fraser fir are often the most expensive species found on a tree lot. Trees are priced by height; the taller the tree, the higher the cost.
The beauty of a green fresh cut Christmas tree is one of the highlights of the Christmas season. White spruce will often start to bud out even as a cut tree and the resulting light green shoots add contrast, color and interest to a tree. Blue-green forms of Colorado spruce will provide a beautiful backdrop for your ornaments. Balsam, Canaan, and Fraser firs have two lines of gray to silver stomata on the underside of their needles that are used in gas exchange between the trees and the atmosphere. As Christmas trees the firs, especially Fraser firs, have a beautiful silvery cast because of these stomatal lines. White pines also appear blue-green because of three or more white stomatal lines on the needles.
Balsam firs are often mentioned as the most fragrant of Christmas trees, followed closely by the other firs and white pine. Canaan firs have become popular Christmas trees because customers often say they combine the silvery beauty of a Fraser fir with the appealing scent of a balsam fir. When the needles of white or Colorado spruce are crushed, the scent is unpleasant to many people.
If you decorate with heavy ornaments, consider buying a Scots pine or a Colorado spruce; their stiff branches will support such ornaments. Fraser fir has the sturdiest branches of the firs. White pine is best decorated with lightweight ornaments, bows, and ribbons because of its soft flexible branches.
White spruce have the shortest (about ½ inch) needles, followed by the 1-inch needles of Colorado spruce and the firs. The needle length of Scots, white, and Norway pine are 2-3 inches, 3-4 inches, and 4-6 inches, respectively. If you are looking for a child- or pet-proof tree, try a Colorado spruce with its stiff pointed needles or a Scots pine with its rigid needles. If it is pain-free decorating you are after, choose one of the firs or a white pine as they are all known for the softness of their needles.
No one likes a Christmas tree that drops its needles too early during the 4-5 weeks of Christmas season. Pines have the best needle retention followed by the firs and then the spruces. Check the freshness of the tree you have selected before leaving the tree lot by shaking it or running your hand gently over a branch and watching for the amount of needle drop. Few needles should drop from the outer edges of the tree branches. Needles and branch ends should feel flexible rather than dry and brittle. More important than tree species though is the care that you give to your tree after you leave the tree lot or farm. If your drive home from the tree lot involves highway speeds and is over 15 minutes long, try to transport your tree inside of a vehicle or wrapped in a tarp on top of your vehicle to prevent wind desiccation. Cut one inch off of the bottom of your tree immediately before putting it into your tree stand so that the tree can continue to take up water. Add water to the tree stand immediately and check the water level 2-3 times per day for the first few days and daily after that, always keeping the water level above that base of the tree. Fresh trees can use one quart of water per inch of trunk diameter each day so be sure to use a tree stand that holds enough water for a 24-hour period. If the stand goes dry, water uptake will stop and your tree will desiccate rapidly. The best placement of your tree to prevent desiccation is away from direct sunlight, heaters, furnace vents, and fireplaces.
Continue to inspect houseplants that spent the summer outside for pests and treat as needed. Outside there are predators and other factors that can keep especially insect pests to a minimum, but once the plants are brought inside, insects and mites can proliferate. There are a number of low toxicity products available from local garden centers labeled for use on indoor plants.
Although it is getting cold, there may still time to put protective barriers around shrubs and young trees to protect them from animal browsing. Tree wrap, chicken wire, and hardware cloth are just some of the many options available. In addition, young trees and some evergreens are susceptible to winter burn. Proper placement in the landscape and also some preventative care can help reduce damage. To learn more, please read Protecting Trees and Shrubs Against Winter Damage (http://www.extension.umn.edu/distribution/horticulture/DG1411.html).
If you haven’t done so already, consider bringing in or draining and covering birdbaths and other sensitive statuary to help preserve it for future seasons. Water expands as it freezes and can crack or contribute to chipping of concrete and other materials.
If you are decorating outdoors with cut stems of evergreens and deciduous shrubs, dried flowers or seed heads, or other holiday ornaments placed in moss baskets, window boxes, or your other sturdy outdoor containers, consider adding a bit of moisture to the soil if it is dry. This will help stabilize the arrangement once the soil is frozen.
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David C. Zlesak, Ph.D.