Poinsettia Care

Question: I am planning a trip away from home for about a week and want to keep my poinsettias looking good enough for a New Years party. What suggestions do you have?

Answer: The first thing to do is to make sure the plants have a relatively long display live remaining. The best way to tell this is to look at the blooms or bloom buds. As seen in the photo to the right the blooms are in the center of the colorful bracts. You should choose plants that have either unopened green buds or slightly opened yellow blooms. If the blooms are dead or dying the plant does not have a long color show remaining.

Your poinsettia can add beauty to your home throughout the holiday season if you place it in an optimal location for its needs. Poinsettia do best in bright, but not direct, sunlight. Put the plant near a sunny window but not in direct sunlight. Direct sunlight could discolor the bracts. On the other hand, low light can cause the plant to lose some of its leaves.

Poinsettias will not tolerate moisture extremes. Do not keep the potting mix too wet or too dry. If allowed to dry out too much, the plant will wilt and drop its leaves. Conversely, don’t allow the plant to remain in standing water. This could result in root rot, which will cause the plant to decline.

Poinsettias do not last long when exposed to extremes in temperature, particularly in drafty locations. This can cause overall plant decline and leaf drop. Keep the plant away from heat vents and outside doors or windows. Try to maintain the temperature at no higher than 70 degrees F. If possible, keep the plant with other plants or set the container in a gravel-filled pan half-filled with water. Doing this will keep the humidity a little higher around the plant in an otherwise dry, winter home. Since you are leaving I would suggest turning your heat down to 55 or 60 degrees F. and this cooler temperature will preserve the color life considerably.

For more information and after Christmas care see the ACES publication:
Consumer Poinsettia Care

Climate Change

I was recently visiting a friends home and we started talking about “Climate Change” and he said, “I want you to read something out of the 1939 Yearbook of Agriculture”. If you remember your history you will recall that this was the time of the “Dust Bowl” in the southern plains. The 1939 Yearbook of Agriculture talked about this disaster as well as the severe flooding in other parts of the country. In general it was a decade of extremes of many kinds. One very interesting notation made was that there was much speculation at the time that the changes were possibly permanent and that they were influenced by mans activities. There is no doubt the wind erosion was due in large part to poor tillage and agricultural practices but the author was very skeptical about climate behavior being a result of human activity.

A recent report also exhibits some skepticism about many of the most used climate models and their reliability in predicting past climate changes. The authors of this study wonder if these models that do a poor job of predicting past changes can be relied upon to predict future changes. This research was published online in the Royal Meteorological Society's International Journal of Climatology.

"The usual discussion is whether the climate model forecasts of Earth's climate 100 years or so into the future are realistic," said the lead author, Dr. David H. Douglass from the University of Rochester. "Here we have something more fundamental: Can the models accurately explain the climate from the recent past? "It seems that the answer is no."

Scientists from Rochester, the University of Alabama in Huntsville (UAH) and the University of Virginia compared the climate change "forecasts" from the 22 most widely-cited global circulation models with tropical temperature data collected by surface, satellite and balloon sensors. The models predicted that the lower atmosphere should warm significantly more than it actually did.

"Models are very consistent in forecasting a significant difference between climate trends at the surface and in the troposphere, the layer of atmosphere between the surface and the stratosphere," said Dr. John Christy, director of UAH's Earth System Science Center. "The models forecast that the troposphere should be warming more than the surface and that this trend should be especially pronounced in the tropics.

"When we look at actual climate data, however, we do not see accelerated warming in the tropical troposphere. Instead, the lower and middle atmosphere are warming the same or less than the surface. For those layers of the atmosphere, the warming trend we see in the tropics is typically less than half of what the models forecast."

Wiley-Blackwell (2007, December 12). New Study Increases Concerns About Climate Model Reliability. ScienceDaily. Retrieved December 17, 2007, from http://www.sciencedaily.com/releases/2007/12/071211101623.htm

Dust bowl picture from: A black blizzard over Prowers Co., Colorado, 1937. (Western History Collection, University of Oklahoma)

Question: I used a live Christmas tree this year and I want to plant it in the landscape. The plant is an Arizona Cypress called ‘Carolina Sapphire’. How large will this tree grow to at maturity and will it grow in our climate?

Answer: Balled-and-burlapped or container-grown Christmas trees can be planted out as landscape trees after Christmas. The sooner you can get it outside and in the ground the better. If you can not plant it right away at least move it out of doors to the cooler environment and keep it well watered. With care and planning, your Christmas tree will serve as a living memory for many years. I used a white pine the first year we lived in our current home and it is about 10 years old and still growing well. On the other hand my mother used a Norway Spruce many years ago and it struggled along for several years before dying at a rather young age. Needless to say some Christmas trees are more suitable to our climate than others. You may have problems with Norway Spruce, Hemlock and Firs but have good success with the Arizona Cypress you mentioned, White Pine, Virginia Pine, Leyland Cypress, Eastern Red Cedar, and Japanese Cedar.

When I lived in Mobile my home was next door to a large wholesale nursery. One December morning I was admiring some of their pyramidal shaped Foster hollies. I told the owner, Tom Dodd III that I thought it would make a great Christmas tree so he loaned it to me for the month and it did make a very nice tree and was no worse for the wear when I returned it in January. I got the idea from my father-in-law who always has a very unusual Christmas tree. A couple years ago he used a six foot tall Satsuma orange tree loaded with fruit. Another year he used a pear tree that was decorated with pears and pairs. For instance, he had a picture of a couple famous doctors and they of course were a “pair-a-docs”(paradox). All his Christmas quests enjoyed the challenge of figuring out what his ornaments represented and each year there is an anticipation of what kind of tree he will come up with.

Back to the original question you asked about Arizona Cypress. You can expect this plant to reach 20 to 30 feet tall, 8 feet wide. It has a very rapid growth rate while young. Plant it in full sun and a well-drained soil. It thrives in hot and dry conditions once established but needs supplemental water the first year. Make sure you remove the bag if it is in a synthetic burlap bag. If you are not sure I would play it safe and take the bag off completely. If it is in a container take it out and bump it on the ground a few times to get off a lot of the loose bark. Plant at the same depth it was growing because setting this plant to deep can be deadly because it needs good drainage.

Think ahead for good tomato crop

Last year was a bad year for gardening in many ways. Tomatoes were particularly hard hit in the early season by a disease that rears it's head from time to time called Tomato Spotted Wilt Virus (TSWV). This virus is usually spread by very small insects called thrips. Infected tomato plants become stunted and often die. Initially, leaves in the terminal part of the plant stop growing, become distorted, and turn pale green. In young leaves, veins thicken and turn purple, causing the leaves to appear bronze. Dead looking spots, or ring spots, are frequently present on infected leaves and stems often have purplish-brown streaks. Fruit, infected with the virus, may exhibit numerous ringspots and blotches and may become distorted if infected when immature.

Currently, there are no real effective chemical controls for this disease in the garden. Keeping the area around the garden as weed free as possible may help by reducing the over wintering host plants. Destroying infected plants as soon as symptoms appear may also reduce spread of the disease. There has been some research that shows a benefit from using an ultraviolet (UV) reflective mulch. UV-reflective mulches are available commercially in small packages for home owners. It is basically plastic mulch with an aluminum foil appearance. It works by repelling the thrips that spread the disease. Lastly, there are some TSWV resistant varieties on the market but they will be difficult to find. This is the reason I suggest you start thinking about your tomatoes now.

I suggest you either contact your garden center and ask them if they plan to have the resistant varieties this year and if not you may want to grow your own transpalnts. I just returned from the Deep South Fruit and Vegetable conference in Mobile, Alabama where Dr. Jimmy Boudreaux from LSU discussed this problem. He mentioned some varieties with good resistance to grow. Previously the one I have grown is Amelia which is a good choice. He mentioned a variety called Bella Rosa that sounds real good. He compared the flavor with a favorite of mine called Celebrity. Celebrity is a great tasting tomato and very popular everywhere it is grown. A couple other resistant varieties you may find available are Crista and RedLine.

Overgrown Boxwood

Question: I have a severely overgrown English Boxwood (Buxus sempervirens) and want to know how hard I can prune it back and when should I prune?

Answer: You can prune boxwoods very severely in the winter but they may take years to look good again depending on the overall health of the plant. I found a video that shows some very severe pruning of boxwoods and it frankly scared me but I asked the Birmingham Botanical Gardens Director (and boxwood expert) Fred Spicer and he gave it a thumbs up.

Most folks would agree it would be best to take the size back gradually (if possible) by regular thinning out of branches to encourage better light penetration and new growth. Take a look at this information from the National Arboretum. They give a great step by step description of proper boxwood pruning techniques. It is not as critical when you do this kind of pruning. It could be done even during the spring and summer months.

Camellia fails to bloom

Question: I have had a camellia near my home for many years and it has never bloomed. It does produce plenty of bloom buds but they never open. Do you have any idea why this happens?

Answer: The disorder you have described is commonly called “bull nose” and the exact cause is not known. In general this disorder is thought to be either an environmental or genetic problem. The environmental issues that could cause this could be as simple as a light problem. Camellias bloom best when they get about three hours of intense morning light followed by filtered light and late afternoon shade. In deep shade the foliage may do fine but they may never bloom well.

Other environmental concerns may be excessive fertility (especially too much nitrogen) and alkaline soils. Normally we don’t have alkaline soils but it is possible, especially near houses that have mortar or brick work. If you fertilizer with nitrogen you may want to quit for a couple years (near the plant root system) and see what happens.

The natural soil for camellias contains humus or well-decomposed organic matter, is slightly acid, and is highly retentive of moisture but drains well. In camellia culture, the value of organic matter cannot be overemphasized, since it improves aeration and drainage and adds moderately to soil acidity.

Pruning at the wrong time can be a problem. Camellias require only light pruning, if any, to remove dead wood, to shape into compact plants, and to thin inside limbs to increase air movement. Do not shear plants or make multiple heading back cuts. The best time to prune is after blooming and before new flower and vegetative buds form. We primarily grow two types in our area. Camellia sasanqua, which bloom in the fall, should be pruned in late winter. For the brave souls who grow Camellia japonica you should prune them in late winter or spring just after blooming is completed.

If the problem is genetic in nature that simply means it does not have the capacity to bloom in our climate or your specefic microclimate no matter what you do. In that case you should enjoy the other fine qualities of the plant or remove and replace with another camellia cultivar or a completely different plant. For more information check out the Extension publication here .

Fall Leaf Color Surprising

Have you noticed that despite the severe drought this year the fall leaf color has been very good in the mid to deep south? I have been totally amazed how pretty the foliage is on many hardwood species especially maples and have also been somewhat dumbfounded. I really expected the leaves to have poor color and to fall early but some recent research may shed some light on why my intiution was dead wrong.

The following information came from a "Geologic Society of America" press release: Soils may dictate the array of fall colors as much as the trees rooted in them, according to a forest survey out of North Carolina.
By taking careful stock and laboratory analyses of the autumn foliage of sweetgum and red maple trees along transects from floodplains to ridge-tops in a nature preserve in Charlotte, N.C., former University of North Carolina at Charlotte graduate student Emily M. Habinck found that in places where the soil was relatively low in nitrogen and other essential elements, trees produced more red pigments known as anthocyanins.
Habinck's discovery supports a 2003 hypothesis put forward to explain why trees bother to make red pigments, by plant physiologist William Hoch of Montana State University, Bozeman. Hoch found that if he genetically blocked anthocyanin production in red-leafed plants, their leaves were unusually vulnerable to fall sunlight, and so sent less nutrients to the plant roots for winter storage.
For trees living in nutrient-poor soils, then, it makes sense to produce more anthocyanins, which protect the leaves longer, so as much nutrient as possible can be recovered from leaves before winter sets in. It is, after all, the process of recovering of nutrients from leaves which turns leaves from green to yellow, orange and sometimes anthocyanin-red.
"The rainbow of color we see in the fall is not just for our personal human enjoyment -- rather, it is the trees going on about their lives and trying to survive," said Habinck's advisor, Martha C. Eppes, a soil scientist and assistant professor of Earth sciences at the University of North Carolina at Charlotte.

The reason the soil-leaf color connection wasn't made long ago is partly because Hoch's hypothesis was needed to put it into perspective. It also might be that many plant researchers were missing the forest for the trees.

My theory for our area is that trees under drought stress were unable to pick up adequate nutrients and are therefore acting as if nutrient stressed. However, I am open to other theories on the matter.