Welcome to Garden Zone, a monthly newsletter for anyone interested in gardening. ​​It's produced by Extension Master Gardener volunteers in Mecklenburg County.

We learned in January’s issue of Garden Zone that the average global temperature has increased by 1.8 degrees since 1895. While North Carolina has warmed slightly less, the State has experienced major changes with the introduction of large urban centers like Raleigh, Asheville, and Charlotte. These cities have drastically altered the landscape.  One of the most notable changes is the creation of urban heat islands and their corresponding effect.

Urban heat islands occur when natural landscapes are converted to cityscapes with high concentrations of impervious surfaces like concrete, asphalt, and buildings.  These areas absorb and retain heat, increasing the average temperature of the surrounding environment. Compounding this effect is the lack of water retention. Impervious surfaces increase stormwater runoff which reduces the amount of water available to plants. This is concerning for urban greenspaces and even your home landscape. 

The urban heat island effect will become more extreme as the climate warms and urbanization increases. Research at NC State shows that warmer temperatures promote the abundance of sapsucking insects like gloomy scale. These insects remove vital nutrients from trees like red maple significantly weakening them and impacting their growth. Additionally, the increased heat stress on red maples makes it more difficult for these trees to move the already limited water available from their roots to their leaves, and a stressed tree is more susceptible to damage and disease from gloomy scale. In short, urban heat islands are no sanctuary for trees like red maple and this problem will only get worse in the presence of climate change.

It is vital to plant trees and vegetation in urban areas to mitigate this effect, but the trees we used to rely on, like red maple, are no longer suitable for the warming urban landscape. We need to look at viable alternatives that are more adaptable to the nonnative landscape we’ve created. Trident maple (Acer buergerianum) a deciduous tree native to Asia tolerates drought, air pollution, and even soil compaction. Also native to Asia is the Shangtung maple (Acer truncatum) a highly heat and drought tolerant tree once established. The native chalk maple (subspecies of sugar maple) resists pests and is highly drought and heat tolerant. These are just a few trees recommended to plant by Dr. Barbara Fair (Extension Horticulture Specialist and Associate Professor - NC State) as substitutes to red maple in our changing climate.

Photo courtesy of EMG Alden Picard

We often think of how to beautify our property but how about reducing noise pollution, cleaning the air, increasing your property value, and improving energy efficiency?  A homeowner can accomplish all of this by PLANTING TREES!   Lucky for us that February and March are prime tree-planting times.   

In the summer, they provide shade that reduces heat gain from the sun.  Think of how much cooler it is under a tree than it is on your patio or driveway.  Plant deciduous trees on the south, southwest, and west sides of your home to reduce air conditioning costs.  After the leaves have fallen, sunlight can shine through in fall and winter to warm the house. 

Winter winds increase our heating bills so plant a windbreak in open areas.  A mixture of evergreen trees and shrubs is most effective when planted on the north and northwest sides of your home at a distance of 2-5 times the mature height of the trees.  Closer to the house, plant smaller shrubs and bushes to insulate it against both winter cold and summer heat. 

So, plant a tree – hug a tree – sit under a tree – whatever!  As Joyce Kilmer once wrote “I thought that I would never see a poem lovely as a tree.” 

Photos courtesy of EMG Gina Tadle

We have all heard the phrase 'leave the leaves' with reference to lawn care in the Fall. In addition to providing nutrition to our garden soil, it has a lesser-known impact on birds.

Leaf litter provides a place for insects to complete part of their life-cycle. Caterpillars, cocoons or a full-grown insect… they are all a key component of a bird's diet. We can attract a variety of birds to our yards by laying out a literal buffet for them by NOT cleaning up the fall leaves. Birds will also visit us more if we keep a brush pile of fallen twigs and branches in an unused part of our yard. It's where they find shelter in inclement weather as well as food since worms and insects live in dead wood. Think of it as a full-service hotel for birds!

If we take a minute to reflect that we are all here together, calling this planet home, and that causing no harm to our fellow residents actually requires us to do LESS on our part... it seems like a no-brainer to do less "cleanup" in our yards and enjoy the show!

Photo courtesy of EMG Parul Srivastava and Dreamstime

If you are like me, you are constantly fighting to rid your yard of spreading invasive plants. Winter is a great time to go after some that are evergreen.  Since most of our native plants are deciduous, the invasives are easier to spot. This week I’ve been working on the Japanese Honeysuckle, a tenacious vine that works, and often succeeds, at covering everything around it. It has a strong presence in the greenway near us and, since the seeds spread into our yard, we will probably never be completely done with it. It is one of the semi-evergreen ones and you can easily spot it right now. The ground is soft from all of the rain we’ve been having, so you can grab a root ball and pull and those long vines will come out of the ground where it has been spreading in all directions. By spring those long shoots will have rooted, be much stronger, and be much harder to get out. If it is already climbing something, cut the stems and then get the roots. If it is a really huge plant that can’t be dug out, cut the trunk near the ground and immediately dab or paint the cut trunk with an herbicide. It won’t take much to do the job.

We are fortunate to have a native honeysuckle which is not only better behaved but is much prettier and is beloved of hummingbirds. If you have a place for a vine, Coral Honeysuckle, Lonicera sempervirons, is a terrific choice, but it may need some protection from deer. Deer seem to prefer the native plants they evolved with, which gives another boost to invasive plants that don’t get eaten.

If you are not sure which honeysuckle you have and don’t want to pull up a native one by mistake, the leaves of L. japonica are broader, more yellow-green, and hairier. The young stems are hairy, and the young leaves are sometimes lobed, which is confusing until you follow the vine back. The young stems and leaves of L. sempervirens are smooth and shiner, not hairy.

Photos courtesy of EMG Jean Wilson  Photo 1: Cpral Honeysuckle,  Photo 2 & 3: Invasive Japanese Honeysuckle

https://plants.ces.ncsu.edu/plants/lonicera-sempervirens/

https://plants.ces.ncsu.edu/plants/lonicera-japonica

By turning meticulously tended gardens and yards into an all-you-can-eat buffet, deer have found the perfect arrow to wound a gardener’s heart. Both beautiful and nuisance, literally nothing is safe from them during a severe winter. However, there are plant choices to lessen the destruction of these doe-eyed creatures.

Aromatic plants like warm climate Lilacs, Tea Olives, Japanese Andromeda (Pieris), Salvias, Verbena, Snapdragon, Catmint, Lavender, Bee Balm, Lemon Balm, Creeping Thyme, Allium, Yarrow, Lantana, Marigold, Wild Garlic, Chamomile, Rosemary, Sage, Chives and other scented herbs are natural deterrents.

Fuzzy, prickly plants and shrubs that encourage deer to move along include ornamental grasses and Pampas, Heartleaf Brunnera, Coleus, Butterfly Bush, Spirea, Viburnum, Lamb’s Ear, Dusty Miller, Lungwort, Blanket Flower, Holly, Barberry, Juniper, Willows and Prickly Pear.

Some poisonous shrubs, plants and flowers, from very mild to extremely, can be lovely additions to the garden.  Consider Lupin, Poppies, Peonies, Iris, Milkweed, Angel’s Trumpet, Monkshood, Tobacco Plant, Caladiums, Bleeding Heart, Foxglove, Hellebore, Spurge, Yew, Wormwood, Daffodils, Crocus, Rhododendron, Hydrangea and winter hardy Oleander.

When volume matters, finely textured plants are not terribly appealing to deer. Consider Dianthus, Amsonia, Coreopsis, Jacob’s Ladder, Scotch Broom (invasive in NC), Clematis, Deutzia, Euphorbia and a nice variety of ferns.

Selecting Cosmos, Echinacea, Baptisia (False Indigo) which is host to several butterfly larvae, Bearded Iris, Lily of the Valley, Red Hot Poker, Russian Sage, Panicle Hydrangea and Red Twig Dogwood will add interest and color to the garden while discouraging deer.  

Photos courtesy of NCSU.EMG  Photo 1: a deer, Photo 2: Lupine, Photo 3: Peonies

Birds seek out birdbaths year-round and they really are taking a bath as well as cooling off.  All the splashing around removes tiny parasites that hide in their feathers.  You will see them gather on the edge of the birdbath or on a nearby branch to preen so they can mend feathers, waterproof them with oil, and remove any other ectoparasites. Bathing and preening improve their insulation, flight, and general health. Bathing and preening may even help them find a mate! Oh, you good looking bird!

Placing and maintaining a proper birdbath is a bit of a responsibility.  The goal is to provide clean accessible water.  

Location, location, location!  Ideally, the bath is in the shade but not directly under bushes and trees or under feeders.  Leaves, sticks, seeds, and bird droppings will pollute the water very quickly.  

5-star clean rating, please.   Flush the birdbath with a hose at least every other day to remove debris and insects.  Every one or two weeks, wash out the bath with one part vinegar to nine parts water.  Avoid soaps that will strip feathers of protective oils. Cleaning in summer months gets rid of mosquito larva. In autumn, flocks of migrating birds could cause the spread of viruses, so cleaning is critical.  In winter, providing a thawed and clean birdbath is easier with a heated plastic birdbath or a birdbath de-icer.   

Two inches of water is a maximum depth.  Creating a shallower area with stones for small birds is a plus.  Solar powered fountains will keep water running and discourage mosquitos from laying their eggs. Moving water also attracts more birds.  Maybe add a rubber duckie or two! 

Resource: https://www.audubon.org/news/why-you-should-keep-your-birdbath-clean

Photos courtesy of EMG Connie Rothwell

Spring Rose Care by EMG Amelia Russell

When the first new growth appears on the roses, the excitement of a fresh new beginning fills the air.  It is time to consider your spring rose care and to plant new rose bushes!

Pruning roses in the early spring is essential to fostering healthy plants and preparing for a successful growing season.  The level of pruning will depend on the type of rose that you wish to grow. Climbing roses, for example, should not be pruned in the spring until after the first bloom, at which point dead wood may be removed and the plant may be shaped.  

Prior to pruning, assess the sharpness of the pruning shears to be used and consider sharpening them.  Shears should also be cleaned periodically with a 70% alcohol cleaning solution to decrease the spread of disease organisms.  

Roses should have been pruned in the late fall (prior to a freeze) to waist-height to protect the canes from inclement weather and wind.  In early spring, around the time that dormancy breaks, cut back bushes to a uniform height and thin the interior canes.  Select four to eight strong, healthy canes that will grow in opposite directions and create a full, rounded bush with open air in the center.  Dead and diseased canes, as well as twiggy or unproductive growth and suckers, should always be removed.  Be certain to mulch thoroughly and remove any weeds. 

When deadheading roses throughout the season, prune down to an outward-facing bud head so that the new growth extends outward from the plant.  This will allow for more air flow throughout the plant and discourage fungal growth.  Just as providing adequate space between rose bushes is essential to provide for sufficient air circulation around the plant and prevent disease, proper pruning can help extend the life and blooms of a plant. 

After pruning or deadheading, always remember to remove all plant refuse from the area of the rose to prevent the growth of disease. 

Finally, as the sun begins to shine this spring, remember to fertilize your roses with a 10-10-10 fertilizer.  Roses do not respond well to over-fertilization, so be cognizant of the instructions on the fertilizer container.  

Attention to deadheading, watering and fertilization throughout the growing season will hopefully yield a bloomtastic year for roses!

For additional information about growing roses in North Carolina, see:  Roses for North Carolina, Horticulture Information Leaflets by Kim Powell at Roses for North Carolina | NC State Extension Publications.  

See also:  Spring Pruning of Roses by Rosie Lerner at https://www.purdue.edu/hla/sites/yardandgarden/spring-pruning-of-roses/ 

Photos courtesy of EMG Amelia Russell and EMG Gina Tadle