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.

Verbena

I have a red verbena in a flower bed that is the toughest plant in my garden. I think it has done exceptionally well because of dry conditions the last couple years. In wet weather my experience with verbena has not been good due to powdery mildew. I saw this morning on science daily the release of a new verbena called "Raider Amethyst" which is described as both extremely drought tolerant but colorful and long blooming. The color looks great as seen here at Texas Techs website. Even though this is a native plant west of the Mississippi it may be worth trying here especially in the droughtier soils or in containers. I am trying to get some seed to plant next year and I will report back on my results.

Greens - good for your heart

I grew up hearing the chant - "bean - beans are good for your heart" and I believe its true but recent research indicates that greens have some unique qualities of their own that can possibly limit the damage done to heart tissue from a heart attack. Researchers think this may explain the low incidence of heart problems in those with Mediterrarean diets which are high in fat.

Last week I enjoyed some wonderful fresh turnip greens called "Shogun" which make a very nice slick leafed green that was easy to clean. I think the cooler weather the last couple weeks has improved the flavor considerably. For colder temperatures why not try kale which is commonly grown as an ornamental (the colorful types). Kale is extremely cold hardy, have very nice foliage and are very healthful plants. They are closely related to a southern favorite - collards and are just as easy to grow.

Lady Beetle

I was visiting at my mothers house a couple days ago (North Alabama) and she was swatting away at lady beetles moving into her house. They are climbing up the side of houses and making their way indoors seeking a place to spend the winter. According to an Alabama Cooperative Extension System (ACES)Publication,

Lady beetles (ladybugs) are normally considered beneficial insects because they feed on pest insects such as aphids in gardens and landscapes. However, the multicolored Asian lady beetle, Harmonia axyridis, can become a serious household pest. These beetles have been reported to congregate on the sides of buildings by the thousands. They will move inside if given the opportunity, and will stain carpeting, wallpaper, and bedding when crushed or disturbed. These beetles are not poisonous, do not bite or sting, are not carriers of disease, and do not eat wood.

The Asian lady beetle was originally released as a biological control agent for pecan aphids as early as 1916 in California. They have been used throughout the United States and in Canada. Asian lady beetles have a wide host range and can feed on many aphids including rose, apple, poplar, conifer, and crape myrtle aphids.

The ACES publication mention a Integrated approach to control of:

Exclusion
Prevention is the key to keeping this lady beetle from getting into homes. A space less than 1/8 inch will allow lady beetles entry. To prevent entry:
Caulk cracks along windows, doors, or other portals of entry.
Seal and screen attic vents. (This is where they get in at my house)
Install tight fitting door sweeps. Gaps under glass sliding doors may be sealed with foam weather stripping.
Seal utility openings (pipes, dryer vents, cable TV wiring ports, etc.) with caulk, steel wool, or other mesh.

Sanitation
Vacuuming or sweeping is the first line of defense once they are in a home. Don't forget to discard the vacuum bag outside when you are finished. Do not crush the beetles as they can stain wallpaper and upholstery.

Chemicals are generally not recommended. The beetles have to be sprayed directly or walk over treated surfaces to obtain a toxic dose. A vacuum cleaner eliminates beetles indoors without leaving pesticide residues on indoor walls and countertops.

A University of Kentucky publication says, "although Asian lady beetles do not transmit diseases per se, recent studies suggest that infestations can cause allergies in some individuals, ranging from eye irritation to asthma.

People should avoid touching their eyes after handling the beetles, and should consult a physician if they suspect they are having an allergic reaction. When large numbers of beetles are flying in the fall, they often land on clothing and occasionally will bite or 'pinch' if in contact with skin. In nature, lady beetles eat other insects and have chewing mouthparts. The bite feels like a pinprick and is seldom serious. "

Retired Entomologist from the Georgia (UGA) developed a trap that an enterprising person could build and it works on these lady beetles and other household flying pest.

Drought of 07

Question: What are some of the possible long term effects of the severe drought we experienced this year?

Answer: I think the long term impact could be great and not just because of the drought. The spring started out with a devastating late Easter weekend freeze event that hammered many of our landscape plants. The damage was most severe north of the metropolitan Birmingham area but the entire northern half of the state was affected. This event laid the groundwork for what could be described as “the perfect storm” (pun intended) of plant stress.

Plants that had already spent energy reserves putting on new leaves had to pull from more reserves to re-leaf after the freeze event. This alone is very stressful but the stress got much worse when the drought hit. As if these two occurrences weren’t bad enough we hit the “dog days” of summer with prolonged exceedingly high temperatures. Because of water restrictions many plants were not watered properly and may have already died this summer. Many more may not have enough energy reserves to regenerate lost roots this winter. It is possible some trees and shrubs that looked fine going into the winter may not leaf out in the spring.

The plants most likely to die will be the very young (5 years or less), overly mature (politically correct for old), previously damaged, overcrowded, and those on poor soils. There is not a lot that you can do at this point except reduce the competition for limited water. For trees in the landscape I suggest you kill the grass underneath the canopy and water (if permitted) the zone near the tree drip line (where outer limbs reach). Plants will use some of their energy reserves to produce new roots even during the winter. The long range forecast is for a drier than normal winter. Therefore, even an occasional deep watering could make a difference this year. Do not fertilize until late winter, if at all and then be very judicious and don’t over apply. Too much fertilizer will stimulate excessive vegetative growth that may further stress the tree.

You may be approached by people telling you to have your trees topped to reduce the stress on them but this is very bad advice. Topping trees is something that should only be done to prevent damage to utility lines. Making large pruning cuts will further stress the tree because it encourages excessive vegetative growth and requires energy reserves to “heal” the wound or fight off pest that enter through the wound. Sometimes trees will naturally lose limbs but you should wait and let the tree “decide” which limbs need removal.. A weak tree will often have individual large limbs die as a way to save the remainder of the tree. In the spring you may notice this happening and subsequently need to remove dead limbs before they become a hazard.

A less noticed but nevertheless real effect of the drought is reduced natural food sources for wildlife. When food sources are scarce in the wild the deer and other wildlife may become a greater problem. Therefore, I expect an increase in wildlife damage to our landscape plants. Also, birds that overwinter or migrate through the Southeast may have a hard time finding food as well. You may want to fill your bird feeders early and often to give them a little extra help this year.

Fragrant plants

While walking in the garden (Birmingham Botanical Garden) I was surrounded by the sweet smell of the Fragrant Tea Olive (Osmanthus fragrans) that we have enjoyed for the last several weeks. Less noticeable but much showier are the first fall blooming Camellia sasanquas. Some of these have the added benefit of fragrance as well. The two I observed in bloom today was 'Maiden Blush' and 'Daydream'. Daydream (pictured at left) was definetly the more fragrant of the two but I really like the light pink with the yellow center of the 'Maiden Blush'.

While Camellia sasanqua is the most cold hardy of the camellias with fragrance there are others that are even more fragrant. The most fragrant camellias are hybrids between two related species. Normally a Camellia japonica cultivar is crossed with one of the following species: C. sinensis (common tea), C. oleifera, C. saluenensis or C. lutchuensis.

For instance, ‘Scentuous’is a C. japonica crossed with C. lutchuensis and it has a rather lovely blush-white flower with a hyacinth scent. 'Fragrant Pink' is another good scented cultivar. It has pink blooms up and down the stems, and a growth habit that makes it look like a winter blooming shrub form crapemyrtle.

New fragrant hybrids are being developed but they have been around a while. ‘Cinnamon Cindy’ was introduced in 1968 from the U.S. National Arboretum. It is a broadleaved evergreen shrub with white fragrant flowers created for greater cold hardiness and better flower characteristics. It grows rapidly with an upright habit. It blooms in early spring and should be hardy in our area.

‘Sweet Emily Pink’ has small pink rose scented flowers that last a long time. It is low a growing, spreading plant that peaks blooming in January and February. Many of the scented cultivars have small blooms but ‘Scented Son’ looks more like its C. japonica parent with the large blooms that come in January and February.

Small street trees

Question: I would like some suggestions on small trees I could use as street side trees or for under power lines.

Answer: This same question could be asked for good selections for road medians where a smaller very durable tree is desired. The plant that immediately comes to mind is the ubiquitous crape myrtle. Crape myrtles are widely planted for a reason. They are tough as nails drought tolerant, they can take tremendous abuse from pruning, and they are very attractive multi-season plants. They would be much more attractive if they were properly pruned (that’s another article). In addition they come in a multitude of sizes from dwarf shrubs of a couple feet to medium sized trees reaching 30 to 40 feet. You can easily find powdery mildew resistant cultivars which once was a very serious flaw in the crape myrtles character.

If you have crape myrtle fatigue do not fear. There are many good choices of plants to fill the niche you have whether under a power line or as a street tree. One smaller tree to consider is 'Brandywine', a red maple with long lasting, eye-catching fall color. Autumn coloration begins in mid-fall and lasts up to 14 days or more, gradually turning from red to a brilliant red-purple. A male selection, 'Brandywine' can be used in the landscape without fear of generating undesirable weedy seedlings. 'Brandywine' is oval in shape and exhibits significant tolerance to leafhopper, one of the major pests of landscape red maples. It is a small maple only reaching 25 feet tall with a 12 foot spread in 12 years of growth. Two other small red maples to consider are ‘Somerset’ and ‘Sun Valley’. These two are also male selections and reach about the same height.

People seem to love the ‘Bradford’ pear despite its terribly weak branching habit. To those folks I would suggest you consider some of the great crabapples. One in particular you might consider is 'Adirondack' which exhibits a combination of many desirable traits that make it a near-perfect crabapple. The narrow, upright-branched growth habit combines with an annual bloom cycle similar to ‘Bradford’ pear. In addition it has an abundance of small, persistent fruit, slow to moderate growth rate, and multiple disease tolerance that is rare in crabapple. The tree will eventually reach a height of 20 feet with a spread of about 15 feet but this takes about 20 years. Since the fruit are so persistent and the birds love them they are not as messy as some crabapples.

Although flowering cherries are not extremely long lived trees they are beautiful plants worthy of use under power lines or as street trees. I would suggest you consider 'Dream Catcher' is a release from the flowering cherry genetic improvement program at the U.S. National Arboretum. It offers year-round ornamental features, high tolerance to insects and diseases, and rapid early growth. It will reach the size of the crabapple described earlier much faster but it will not live as long. Flowering cherries must be planted in well drained soils but they are not very drought tolerant.

A wonderful small flowering tree that is very drought tolerant is Chaste tree (Vitex agnus-castus). Like many members of this plant family, Chaste tree attracts butterflies and other insects. The older cultivars had small spikes of flowers in pale lilac, mauve, off-white or light pink, but modern, much improved varieties such as 'Montrose Purple', LeCompte', or the 'Salinas Pink' have spikes as long as 8 to 12 inches in length. The blooms remind you of butterfly bush or lilacs. Although the blooms are not notably fragrant like the lilac they may produce aromatic black or brown seeds, but if the spent spikes are cut off promptly after the first flowering the shrub will bloom again and again all summer.

These are just a few choices to consider. For more information about good small trees to consider visit: http://www.powertrees.com/ .