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    Save the Date: Perennial Plant Society’s 30th Plant Sale is April 4, 2020, 9 a.m. – 1 p.m. at the new Expo 3 Building at The Fairgrounds Nashville. Here’s where you can find the newest varieties of perennials, shrubs, vines and annuals from local growers, along with long-time, never-fail favorites, ready for spring planting. Learn more at the PPS website.

     

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Japanese maples stand out in winter

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‘Japanese Sunrise’ is a favorite cultivar for many home gardens because of its multi-colored winter bark. Photo by S. Hamilton, courtesy UTIA.

On a snowy, gray day, what plant can add a bit of cheer in the landscape? Japanese maples, says Sue Hamilton, director of UT Gardens. Each month, the University of Tennessee Institute of Agriculture highlights a “Plant of the Month,” and Japanese maples get the honor for January 2017. Several selections exhibit brilliant bark color when the temperature falls – bright red or orange or yellow or coral pink, “They make quite a show in the winter landscape,” she says.

Sue says they’re also easy trees to maintain. Depending on the cultivar, the size can range from 6 feet to 25 feet tall, but many are in the 10 – 15-foot range, which makes them a good addition to almost any landscape.

“Foliage is a lime green in spring, darkening in color as summer approaches,” she says. “Fall foliage is either a bright, showy shade of yellow or a fusion of red, orange and yellow.” They do best in moist, well-drained soil that is slightly acidic. The grow in partial shade but bark coloration will be best when the tree grows in full sun, and young twigs and branches will be more color intensive that the tree trunk itself, she explains. Continue reading

Remove English ivy from trees

The large trees around our home are covered with English ivy. Is there a way to keep it from growing up into the limbs of the trees?

P1040778 (2)English ivy growing up into trees (and another invasive creeping vine, wintercreeper euonymous) are most evident now, when the trees are bare. It’s this time of year when you can see just how quickly and how thickly those vines – which are evergreen — can climb into the tree canopy. Left to grow, English ivy vines can engulf the tree within a few years.

Once the vines have grown up into the limbs, there is no quick and easy way to get them down. The vines will have grown stout trunks that continue to reach up and branch out as they cling to the bark. The National Park Service, which has an interest in keeping English ivy from displacing native flora on public lands, suggests several methods for controlling the vine. It likely will require a combination of manual, mechanical and chemical methods. Continue reading

Replace landscape plants in fall and winter

We have lost many of the shrubs around our home. How late can we replant all of the landscaping around our residence? Is November too late?

ball burlap treesIf you are planting shrubs and trees, November is actually a good time to replant. Trees and shrubs planted when they are dormant have an easier time establishing good root systems before they begin actively growing again next spring. They will need to be watered at planting time and throughout the season, but not as often as you would have to provide water in spring or summer.

Here are general guidelines from UT/TSU Extension for planting balled-and-burlapped and container-grown trees and shrubs:

-Choose your location and begin by digging a wide hole, two or three times the width, but no deeper than the height of the root ball.

-Handle the trees carefully before you plant. Never pick up or carry a tree by its trunk, especially a balled-and-burlapped tree, due to the weight of the root ball. If they can’t be planted right away, water the trees well and place them in an area away from direct sun.

-Water a plant in a container before you take it out of the pot. After you remove the plant, cut any roots that circle the ball of soil (if the roots and soil don’t come out easily, cut the plastic away from the root ball. Don’t pull the plant out by its trunk). Use a sharp knife to make two or three vertical cuts, and gently loosen the ball to expose more roots to the soil.

-Place the plant in the hole so that the top of the root ball is an inch or two above the soil line. Remove any nails or rope lacing and cut away the burlap, leaving the burlap at the bottom of the root ball. If there is a wire basket, cut as much of it away as you can without disturbing the root ball.

– Backfill the hole with the soil that was removed from the hole, watering when the hole is about half full and again after you finish backfilling. Rake over the soil to even it out with the ground, and cover the area with 2 or 3 inches of mulch (keeping the mulch away from the shrub’s trunk.

-Don’t forget to provide water to newly planted shrubs and trees if the weather is dry.

Prune crape myrtle without committing ‘crape murder’

I have developed my crape myrtles into tree forms. Every year I have to cut back the suckers that grow from the base of the trees at ground level. Is there anything I can do to eliminate the suckers?

Crape myrtleThe suckers that grow from the ground around crape myrtles can be the result of improper pruning. If you top the plants every year (and garden experts sometimes refer to this as “crape murder”) they respond by sending up shoots from the base.

There are many sources for information on pruning crape myrtles, but one good one comes from the Virginia Cooperative Extension of Virginia Tech and Virginia State University. Their suggestion:

Prune crape myrtles as you would any other tree or shrub – by cutting back to a bud, a side branch or a main stem, giving consideration to the ultimate shape of the plant. If you need to cut off only part of a branch, cut above an outward facing bud or side branch. If you need to remove an entire branch, cut just outside the branch collar on the stem, where the branch is attached.

Don’t make random cuts in the middle of a branch or stem. Topping a crape myrtle – or any tree, for that matter – can lead to stem decay and more dead branches. It also encourages the growth of weak shoots at the top of cut stems, which can become top-heavy with flowers and break in a strong wind.

The Virginia Cooperative Extension notes that re-suckering can sometimes by suppressed by applying naphthalene acetic acid after the suckers are pruned. Crape myrtles that are given too much fertilizer may also produce suckers, and have fewer flowers. They advise not to fertilize unless a soil test indicates the need to do so.

The best time to prune crape myrtles has passed for this year. Do the job in late winter or early spring, before new growth begins.

 

This weekend: Beautiful bonsai

bonsai2Bonsai expert Owen Reich invites garden enthusiasts to the Nashville Bonsai Society’s Regional Bonsai Expo July 11 – 13 at Cheekwood Botanical Garden. Reich, Jim Doyle and Young Choe are guest artists, and there will be more than 50 bonsai displays, along with workshops, exhibits and vendors.

The photo above is of a Swamp Rose (Rosa palustris) that Reich collected in Tennessee and trained as a bonsai. “There will be a number of bonsai on display this year created from trees and shrubs native to the United States, as well as high-end bonsai imported from Japan,” he says. The stand in the display was made in Chattanooga by Tom Scott, and the container is a 250 – 300 year-old Chinese container called a Kowatari Shirogochi Pot.

The picture is just a sample of the unique and unusual bonsai on display this weekend. Complete details here.

A sticky hackberry situation

QUESTION: We have a question regarding one of our large hackberry trees. It’s covered with little white flying bugs and the leaves have a sticky residue. What causes this and is there something that we can do about it?

Asian wooly hackberry aphids are a nuisance, but won't harm the trees.

Asian wooly hackberry aphids are a nuisance, but won’t harm the trees.

The bugs you are seeing are called Asian wooly hackberry aphids, and they seem to make an appearance about this time every year. They feed exclusively on hackberry trees, and like all aphids, they feed by piercing the leaves and extracting the juice. The sticky residue is what they excrete after feeding on the leaves, a substance called honeydew. Another byproduct you may notice is a black mold that grows on the honeydew, which is called sooty mold.The aphids apparently do not do enough damage to harm the tree, they are just a nuisance, mostly in late summer and early fall when their population grows due to the many generations that have been produced. If it’s a nuisance you can’t tolerate for some reason, there is a systemic insecticide product that is said to be effective in controlling aphids, but it would not do anything to solve this year’s population. There are several brands available, but the main ingredient is a chemical called imidacloprid, and it should be applied to the ground around the tree in early spring, where it will be taken up via the tree’s vascular system into the leaves.

Not much, then, can be done about this year’s population of hackberry aphids. Hose off the cars, the deck, the lawn furniture and anything under the trees that are sticky from the honeydew, and take comfort in the knowledge that they are a temporary annoyance, and will be gone in a few weeks.

For trees and shrubs, prime planting time

QUESTION: I have a hydrangea that I bought at a nursery last spring, and it’s still in the pot it came in. Is it too late to plant it?

Fall is a good time to plant hydrangeas and other woody ornamentals.

Fall is a good time to plant hydrangeas and other woody ornamentals.

I’m sure every gardener has, at some point, bought sturdy plants in the spring, but somehow never got around to putting them in the ground (I know I have!). You can be sure that your hydrangea will be happier in the ground than it will be if it has to struggle through the winter in a plastic pot.

In fact, fall and winter are good times to plant woody ornamentals, when they are dormant and have fewer energy requirements. They still need water, but require less than they would in spring going into the hot summer. In fall, new trees and shrubs can begin to establish a strong root system and be ready to begin new growth next spring.

Here are general guidelines from UT/TSU Extension for planting container-grown trees and shrubs:

-Choose your location and begin by digging a wide hole, two or three times the width, but no deeper than the height of the root ball in the container.

-Water the plant before you take it out of the pot. After you remove the plant, cut any roots that circle the ball of soil (if the roots and soil don’t come out easily, cut the plastic away from the root ball. Don’t pull the plant out by its trunk). Use a sharp knife to make two or three vertical cuts, and gently loosen the ball to expose more roots to the soil.

-Place the plant in the hole to that the top of the root ball is even with the soil line or an inch or two above it, and backfill the hole with soil and water again. Rake over the soil to even it out with the ground, and cover the area with 2 or 3 inches of mulch (keeping the mulch away from the shrub’s trunk.

-Don’t forget to provide water to newly planted shrubs and trees if the weather is dry.
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Evergreens turning ever-brown

QUESTION: We are seeing many evergreen trees — Leyland cypress and others — with big sections of brown limbs. Is that due to the drought? Or is there some other problem affecting the trees?

The drought this summer plays a big part in the browning of Leyland cypress, but it’s not the whole story. Alan Windham, at UT Extension’s Soil, Pest and Plant Center says the branch dieback is the result of a one-two punch: drought and seirdium canker, a fungus that appears on branches or stems and in branch axils and causes the branch to die. “I’ve seen more damage this month than I can remember in several years,” Windham says.

I found a good description of seirdium canker at the Web site of North Carolina State University’s Plant Pathology Extension: The cankers are brown or purple sunken patches on the bark, and may be accompanied by a flow of resin. Affected branches may be scattered randomly throughout the tree; they turn a reddish-brown color, in striking contrast to the green, healthy foliage. The fungus can be spread by splashes of rainwater or water from sprinklers, or it can travel from branch to branch on unclean pruning tools.

There are no chemicals recommended to control the canker. Brown branches should be pruned and destroyed as soon as possible. Prune at least an inch below the canker, and sterilize the pruning tools between cuts by dipping them in rubbing alcohol or a solution of 1 part chlorine bleach to 9 parts water. Plants that are severely affected should be removed and destroyed. Watering by drip irrigation during drought can help prevent problems, Windham says.

Upright arborvitae are also having trouble due to the drought. Windham explains: Plants have different strategies to survive: some plants sacrifice older leaves to protect new shoots; some have waxy leaves, some plants roll their leaves or close up to prevent water vapor from escaping.

“Then you have plants like arborvitae, where it’s all or nothing. It’s as if the plant is saying, ‘We’re going for broke. Everything survives or nothing survives.’ Well, this strategy didn’t work out too well for many arborvitae I have seen.”

In this case, the only solution is to remove the dead trees and start again.

 

Mulching trees; and a stack of new books

QUESTION: How should mulch be put around trees — piled high or spread even with the ground and good edging to keep water within?

Unfortunately, this is not the best way to mulch trees.

There are many good reasons to use mulch around trees in a landscape. It keeps the soil warmer in winter and cooler in summer; it helps the soil retain moisture; it helps control weeds, and improves soil fertility by adding organic matter. It keeps mowers and string trimmers at a safe distance from the tree trunk, plus, it looks nice.

There are a few “rules” for proper mulching, but none of them include piling mulch up high around the trunks of trees. In fact, it’s a bad idea. Here’s why:

Plants need oxygen in the soil, and mulch that is too thick – more than 4 inches – restricts the soil oxygen exchange, according to the UT Extension’s publication on mulching trees and shrubs. Roots will grow up to find more oxygen, instead of down and outward through the soil. Too much mulch also causes too much moisture in the root zone, making roots susceptible to rot, insects and diseases. Cracking in the bark creates an entry point for insects and fungal growth, and invites rodents to chew the bark and damage the trunk or even girdle the tree – destroying the bark all the way around, which is a quick cause of a tree’s demise.

Unfortunately, this so-called “volcano” mulching, with the mulch placed in a cone around and next to the trunk, is a common practice. Here’s the proper way to place mulch, according to UT Extension (and other good sources):

Apply mulch in a ring no more than 2 to 4 inches deep, at least 4 to 6 feet in diameter around the base of the tree. Place it so that it tapers out to the ground level at the edge of the ring. Do not pile the mulch around the trunk; pull it several inches away so that the base of the trunk is exposed and air moves freely.

Spring reading

There are several new gardening books out this spring. Here’s a roundup:

* I’m slowly making my way through Women and Their Gardens: A History from the Elizabethan Era to Today, by Catherine Horwood (published by Ball Publishing, an imprint of Chicago Review Press). Focusing on the fact of history that women have often been excluded from the serious study of plants, Horwood brings these women into their rightful place in the horticultural spotlight. At more than 400 pages, there is much to be discovered about these pioneering women. I have just learned, for instance, that in 1897, Beatrix Potter was snubbed in her attempt to present research on spore germination of a rare form of fungi. She went back to private research and to her other specialty, detailed watercolor illustrations. A hundred years later, the artist famous for her beautiful childrens’ book illustrations was honored by the Linnean Society with a distinguished lecture entitled “Beatrix Potter as Mycologist.” So there.

* You may remember Graham Kerr as a cookbook author, TV personality and chef who called himself The Galloping Gourmet. His new book is Growing At the Speed of Life: A Year in the Life of My First Kitchen Garden (published by Perigee Trade Paperbacks). He acknowledges from the first page – from the cover, really – “As the Galloping Gourmet, I cooked just about everything that grows – but I’d never grown a thing I’d cooked.” He set out to change that, and the book outlines much of what he learned in that year, and what he expects to learn about growing food in the years ahead. It’s a charmingly personal account, and with a shout-out to “First Lady Michelle Obama putting spade to turf on the White House lawn.” His focus is on the basics, the favorite vegetables and most-used herbs, and with recipes, of course.

* Local gardener and garden blogger Barbara Wise, author of Container Gardening For All Seasons (published by Cool Springs Press) makes assembling gorgeous containers easy by providing, cookbook-style, “recipes” and shopping lists and assembly instructions for about 100 container combinations. (My thanks to Barbara, because I heard about the book just as I was compiling information on container planting for the “Grow a Green Thumb” class I’m leading right now for Lipscomb University’s Lifelong Learning series. What a great resource!)

* For the more ambitious gardeners who include fruit-growing in their garden and landscape plans, there is Grow Fruit Naturally: A Hands-On Guide to Luscious, Homegrown Fruit, by Lee Reich. In my semi-sunny garden, strawberries (apparently, to feed the rabbits) and blueberries (for the birds) are about as far as I’m willing to venture into fruit-growing territory, but if you’re serious about getting fruit from tree to table, this book is for you. It helps you plan, choose and maintain plants in the garden or in containers, and learn ways to control (or avoid) common pests and diseases without toxic sprays. I did just buy a ‘Meyer’ lemon shrub to add to our container collection of things that need to be pampered, so maybe this will help us keep it alive. The eye-candy photos make leafing through the book a pleasant distraction. It’s published by Taunton Press.

* Speaking of nice photos, Rodale Books has published The Photographic Garden: Mastering the Art of Digital Garden Photography, by Matthew Benson, a professional photographer and contributing editor to Organic Gardening magazine. Since part of the joy of gardening is taking pictures of what you grow and sharing them with other gardeners, it would be lovely to know how to do it beautifully. Read the book before the next time you take your camera out, and maybe your garden photos will jump to the next level right away.

* Finally, in the stack of new books: Vegetable Gardening the Colonial Williamsburg Way: 18th Century Methods for Today’s Organic Gardeners by Wesley Green (also published by Rodale). Do you grow salsify? Have you ever heard of skirret? These may not be at the top of everyone’s list of favorite vegetables, but in the 18th Century they were likely growing alongside the onions, garlic, melons, chives, sweet potatoes, beets, parsley and many other things that are familiar in our gardens, and they grow now at Colonial Williamsburg, one of the nation’s best historical preservation sites. The focus in this book is the traditional cultivation methods that are still good for today’s organic gardens. Green, the author, founded the Colonial Garden and Plant Nursery in the Historic Area of Colonial Williamsburg and he and another gardener, Don McKelvey, study and interpret 18th-Century plants, tools and techniques. This book is the beautiful record of that impressive work.

 

Banish the Bradford pear

QUESTION: When should Bradford pear trees be pruned? Is now a good time? How far back should you prune them?

Bradford pear trees are the first to flower in spring, but they are not a good choice for landscape trees.

I’ll answer the last question first, and echo the thoughts of many landscape and forestry experts who believe that these trees should get just one pruning cut – about an inch above the ground.

Seriously, Bradford pears (Pyrus calleryana Bradford’) are not good landscape trees, no matter how lovely they are this time of year. They live fast and die young – a 25-year-old Bradford pear is probably near the end of its life. Because their heavy limbs grow at narrow angles, they tend to split apart. And because they shoot up so quickly and easily, this import from China has been placed on alert as a possible threat by the Tennessee Exotic Pest Plant Council. So, is it time to reconsider?

But back to the question: It’s good to prune trees in late winter, while they’re still dormant. As you are no doubt aware if you’re in Middle Tennessee, “late winter” now seems to mean the same as “spring,” and most things are no longer dormant. So if you need to prune, do it now, before the tree leafs out fully and you can still see the branch structure easily.

Really, though, wouldn’t you rather have something else? Landscape professionals suggest a couple of good native alternatives to the Bradford pear: downy serviceberry (Amelanchier arboria), which has white flowers in spring, dark green foliage in summer and red berries in the fall; and Fringe tree (Chionanthus virginicus), white flowers, green leaves, small blue-black fruit enjoyed by birds in the fall.

Either would be better than a Bradford pear, guaranteed.

 

O, Christmas pine

QUESTION: I’m using a Norfolk Island pine as a small Christmas tree. What do I need to do to keep it looking nice, and how do I care for it when the holidays are over?

Norfolk Island pine provides a nice alternative to the big tree at Christmas, especially if your space is small or your decorating is simple. It’s best not to load it down with large, heavy ornaments that could break the feathery limbs. Use lights sparingly, if at all, and remove them as soon as you can after Christmas is over.

When it’s time to change it from a Christmas tree to a houseplant, place it in a spot (preferably in a cool room) that gets bright, indirect light – a south- or west-facing window is good – and give it a quarter-turn once a week to encourage it to grow straight up.

The biggest threats to Araucaria heterophylla (that’s the tree’s botanical name) are dry soil and dry air. Keep the soil consistently moist, but don’t let the pot sit in water. Increase humidity in its environment as much as possible. A daily misting could go a long way toward keeping the plant healthy. If the air remains too dry, the Norfolk Island pine responds by dropping its needles, and once they’re gone, they don’t grow back.

Houseplant specialists suggest using a balanced fertilizer once a month in summer, and be on the lookout for pests. Spider mites and mealybugs are drawn to this plant. A cautionary note about placing it outdoors: it’s a very tender plant, and will be damaged if the temperature falls below 40 degrees.

With care, a Norfolk Island pine can last for many years. They grow very large in their native South Pacific environment, but in a home, the tree usually grows, over time, to about 6 feet.

Water in winter

Landscapers know this, but we casual gardeners may not remember that even though it’s winter, the garden still needs water. Pay special attention to newly planted trees and shrubs, broadleaf evergreens (which continue to “breathe” even during winter), pansy beds and perennials that you planted in the fall.

Mulch keeps soil from drying out too quickly, but if the weather is cold but very dry, the soil will eventually dry out.