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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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Care for peonies after they bloom

Now that the peonies have finished blooming, what’s the best thing to do with them – leave them or cut them back? Ours often get an ugly coating of powdery mildew on the leaves in the summer. Is there a way to prevent this?

After they bloom, peonies spend the rest of the summer gathering strength to bloom next year before they die back to the roots in winter. A good first task for the gardener is to cut off the faded flowers. Garden expert P. Allen Smith suggests removing the seed pods and lightly fertilizing in late spring or early summer. But be sure to leave the foliage. After the blooms are gone, the rich green leaves of peony shrubs remain an attractive feature in the garden – except when it develops a case of powdery mildew. Continue reading

Coffee grounds as mulch? Don’t do it!

I get coffee grounds from my local coffee shop. Can I use them directly on the soil as mulch (without mixing anything into it except to rake it into the soil)? The grounds are wet when I get them from the coffee shop. Should I let them dry out a little before putting it on the soil?

coffee groundsIn just about every listing of “ingredients” for a successful compost pile, you’ll find coffee grounds among the nitrogen-rich kitchen waste “green” ingredients that make up the mix. But it’s a mistake to use coffee grounds alone. They are very acidic, and over time will change the pH of the soil – the measure of its acidity or alkalinity – to the point that plants that prefer alkaline soil will suffer. Continue reading

Prune roses for better blooms

We have a rose bush that is out of control and really needs pruning. Can it be done now? Or is it better to wait until next spring?

Yellow rose

Rose experts say that roses can be pruned anytime they are actively growing. Start by trimming out the older wood first, along with any dead or dying canes. You may also want to remove canes in the center of the bush to provide better air flow, any canes that cross and rub each other, or any twiggy growth that might be tempting to spider mites.

The Nashville Rose Society provides general pruning guidelines: each pruning cut should be made about ¼-inch above an outward-facing bud eye (where the leaf is attached to the stem). Use sharp bypass pruning shears, which will make a clean cut without crushing the stem.

An added tip: remove the spent blooms of roses regularly to encourage the plant to bloom more.

Serious rose growers may do a more severe type of pruning in the fall to winterize bush roses. Nashville Rose Society also provides general guidelines for this process: Stop fertilizing roses early in August to allow the plant to slow down producing new growth, then in early October, stop cutting off the dead flowers. In late November or early December, cut the canes back to 2 to 3 feet and place a mound of mulch around the bush.

Next spring, once the weather begins to warm up, move the mulch away from the roses and prune to about 12 inches to get new growth.

In Saturday’s Tennessean

land trust signThe Ernest and Berdelle Campbell Land Trust Garden is a quarter-acre oasis in Nashville’s tightly-packed Germantown neighborhood. “This will always be green space,” Berdelle Campbell says. Read about the garden and Berdelle’s agreement with The Land Trust for Tennessee in Saturday’s Tennessean, and find more here about my visit with Berdelle, and more photos from the garden.

Free daylilies!

A Middle Tennessee reader emailed last week to say that she has a back yard full of daylilies that she can no longer take care of, and she is trying to find a home for them. “There is a huge assortment in lots of different colors and types, mostly full size but some miniatures,” she wrote. “My grandmother and mom collected them over the year and I don’t really know any of their names.”

If you are looking for daylilies, are willing to take a chance on sizes and colors, and can dig them up yourself, she is willing to donate. Interested? Email me at gloria@gloriaballard.com and I will put you in touch.

Fortunately, the best time to dig and divide daylilies is coming up. I wrote about how to do that task here.

Spider mites can ruin your roses

What could be stripping the leaves off the branches of my roses? I spray with a product that is supposed to protect roses from insects and diseases, but it hasn’t helped.

Knock Out roseKeep an eye on roses when it’s hot and dry. That’s when spider mites do their worst damage, say rosarians at the Nashville Rose Society, and they can turn a lovely rose bush into an ugly mess.

The tiny creatures get on the undersides of leaves and feed on the plant’s juices. The damaged leaves look speckled, turn yellow and fall off.

Spider mites are not insects; they are more closely related to spiders, so insecticides won’t have any effect. You can use a miticide, but it can be expensive. The best and cheapest way to control them is with a blast of water directed at the undersides of the leaves, rosarians say. If you do this every three days for a week or so, you break the mites’ gestation cycle.

Here’s a little more information about the tiny arachnids: Adult mites are less than 1/50 inch long. They use their mouthparts to pierce individual plant cells and remove the liquid. They produce webs that can coat the foliage with a fine silk that collects dust, making the leaves look dirty.

You can’t see them, but you can certainly see the damage. Heavily infested plants will be discolored, and if they are not controlled, the rose can be stunted, or even killed.

Prune azaleas soon after they bloom

Our azaleas are too large and need to be trimmed. When is the best time to prune them?

AzaleaIn general, azaleas rarely need pruning, but if you find you need to reduce the size of the shrubs, the best time to prune them is right after they finish blooming. The buds for this year’s azalea blooms began forming last summer, so if you prune now, before they bloom, it means you are cutting off many of the flowers before you have a chance to enjoy them.

Southern Living garden writer Steve Bender, who edited the new edition of the Southern Living Garden Book, suggests this method for pruning azaleas: determine where the height or width needs to be reduced. Then, using hand pruners (or loppers, if the branches are thick), reach in and cut back individual branches to different lengths to create a mounding shape. Do not, he admonishes, use hedge trimmers to shear azaleas. Besides looking boxy and unnatural, this results in flowers and foliage that grow only on the outer portions of the shrubs.

Two other notes from Steve’s advice, which you can read here:

-If you do the job at the proper time, you can cut evergreen azaleas back pretty hard – even back to bare wood — and they should survive and flourish.

-If yours are the ‘Encore’ type of azaleas, which bloom in spring and again in late summer or fall, prune right after the spring bloom.

Divide irises after they bloom

Our bearded irises are coming up and they’re pretty crowded this year, and need to be dug up and divided. If we divide them now, before they bloom, will we still have flowers this year?

Purple irisIf your iris bed is crowded but still producing blooms, it is best to wait until later to dig up the iris bed and divide the rhizomes. The experts at the American Iris Society and other sources say iris beds should be divided every three to five years, and suggest mid- to late-summer as the best time for this task.

When the time comes this summer, here is the method suggested by author Judy Lowe in Month-by-Month Gardening in Tennessee & Kentucky:

Cut the leaves in a fan shape about 6 inches tall, then lift the clump with a spading fork, wash off the dirt, and inspect the rhizome for soft spots, damage or disease.

Cut the rhizome into smaller pieces with a sharp knife, making sure each piece includes an eye or a bud. Cut away any older growth. Lowe notes that iris rhizomes are susceptible to fungal problems, and suggests dipping the rhizome briefly into a solution of one part liquid bleach to nine parts water.

Replant the sections: Dig a hole and make a mound of soil in the center, then place the rhizome on top so that its roots spread over the mound. Cover the roots, but maintain the rhizome at soil level or just below it. Bearded iris rhizomes that are planted too deep may rot, she says. Water the bed well.

Dividing in summer allows the rhizomes to become established before the end of the growing season, and more likely to bloom well next spring.

Color Garden book giveaway

Thanks to readers who left comments this week for a chance to win The Nonstop Color Garden by Nellie Neal. Constance is the winner of the random drawing.

Nellie, her book, and information from Doris Weakley of the Perennial Plant Society of Middle Tennessee were featured in a story in last Saturday’s Tennessean. You can read it here.

And watch for another book giveaway soon.

What’s blooming indoors? Meyer lemon

I have a Meyer lemon tree that I keep indoors. It’s often full of blooms and the flowers smell wonderful. I’m always looking for lemons to start growing, but the flowers dry up and fall off and I never get any fruit.

meyer lemon flower closeup 3As long as the tree is indoors where the air is still and there aren’t any insects flying around, your Meyer lemon will most likely continue to be a delightfully fragrant but non-fruit-bearing plant. What the flowers need to produce fruit is the process of pollination.

You’ve heard of the birds and the bees, right? Outdoors, flying insects (bees and other pollinators) go from flower to flower, dipping into the pollen on the stamens – the cluster of thin filaments — and spreading it to the stigma at the center of the flower.

Indoors, if you want fruit, you’ll have to take care of that little detail yourself. Lemon trees are self-pollinating, meaning that the flowers shed pollen directly onto the stigma, but they still may rely on wind or insects — or human intervention, if necessary — to shake things up.

Here’s how you can help: As the flowers open, use a cotton swab or a small artist’s paintbrush to collect pollen from the anthers (the tips of the stamens), then rub the stigma with the swab to transfer the pollen. It’s a slow process, but the tree should begin to produce lemons (which grow fairly slowly, by the way).

Meyer lemons growing indoors where winters are cold need a lot of sunlight, and they also benefit from time spent outside when the weather warms up. Place a lemon tree in a protected spot outdoors, moving it gradually into full sun, when nighttime temperatures stay above about 50 degrees. Outdoors, the bees will do the job of pollinating the flowers, of course.

In general, Meyer lemon trees thrive in good potting mix in a container that drains well. Make sure the soil doesn’t dry out completely, but don’t overwater it, either. Fertilize regularly with an organic fertilizer designed for citrus, following directions on the label. (I’ve used Espoma’s Organic Citrus-tone citrus and avocado food, with good results).

Prune clematis for a better show of blooms

Question: Our spring-blooming clematis vine has grown tall and seems very healthy, but it blooms mainly at the top. The bottom six feet has very few blooms and not much foliage this spring. Can you tell me why?

clematis 2Clematis flowers clambering over a sturdy trellis or other support are a lovely sight each spring. When this woody flowering vine gets too top-heavy, with all the flowers at the top and bare stems at the bottom, the problem has to do with pruning – or lack of it. Early-flowering clematis blooms in spring from buds formed last season. Plant experts recommend pruning it each year to help the plant produce the maximum number of flowers. The time to do that is as soon as you can after it finishes blooming to allow time for new growth to produce flower buds for next year.

Horticulturists writing for a fact sheet from Ohio StateUniversity say that sometimes you can cut back into older wood of old, neglected plants to encourage new buds to break. The vines are most likely tangled, so when you prune, make cuts carefully, and train the stems to cover the maximum are on their support.

Note also that there are other varieties of clematis that bloom a bit later, on new growth, and those varieties should be pruned in the winter.

In general, here is what clematis needs to thrive: Loose, fast-draining soil that is high in organic matter, and regular water. Gardeners like to say that clematis prefers to have its head in the sun and its feet in the shade, so provide a thick layer of mulch to keep the roots cool. You can also plant a ground cover such as mondo grass around the base of the clematis vine.

Azaleas thrive when conditions are right

Question: Our azaleas on the eastern side of the house have never been very showy. The flowers are always puny and short-lived. This year one plant’s leaves are quite yellow. Is this is sign of disease or need for fertilizer? Any advice on helping the plants do better?

AzaleaFirst, consider what azaleas need to grow well, and you may find that one or more of these conditions (outlined by the Azalea Society of America) is not being met:

-Slightly acid soil (pH 5.5 – 6; a soil test can provide that information about the soil in your azalea bed).

-Enough sunlight. Less than 3 hours of sun reduces the number of buds.

-Adequate moisture. Like many other shrubs and perennials in the garden, azaleas need about an inch of water (rainfall or watering) per week. Mulch around the shrubs can help the soil retain moisture.

There are several factors that affect the number of blooms — including the fact that some are just “shy bloomers,” according to the Azalea Society. Lack of moisture during late spring and summer also affect bud formation, or there may be a phosphorous deficiency (again, the soil test can determine if that’s the case).

As for those yellow leaves: If the yellowing is between dark green veins, the condition is called chlorosis, which is usually caused by an iron deficiency, alkalinity of the soil, potassium, calcium or magnesium deficiency, or too much phosphorous. Iron sulfate or sulfur can acidify the soil.

Leaves that are uniformly a yellow – green color may just need more nitrogen. That soil test should be your first step to determine what the problem may be.

Rosemary: Time to start over

After this winter, my rosemary looks as dead as dead can be. Is there a way to tell now whether I should go ahead and pull it up and replant, or should I wait?

RosemaryRosemary is considered a marginally hardy shrub in this part of Middle Tennessee (Zone 7a). The last few winters here have been kind to us, and most gardeners’ rosemary has survived, especially the more cold-hardy varieties such as ‘Arp’ and ‘Hill’s Hardy.’

But this winter delivered a knockout punch to everyone’s rosemary. To test for life, scratch the bark on a stem and if you see green underneath, there is still life in there. But I’m guessing it’s as dead as it looks. Might as well pull it up and start over.

For better luck keeping rosemary alive during winter, choose one of the more cold-hardy selections. The U.S National Arboretum in Washington, D.C. makes several recommendations at its web site for Rosmarinus officinalis varieties that have made it through winter in the National Herb Garden with little or no dieback — ‘Albus,’ ‘Logee’s Light Blue’ and ‘Salem’ among them (no word at the web site on whether they made it through this winter, though). As a rule, they say, cultivars with thinner leaves and lighter flowers are hardier. Prostrate types of rosemary are least hardy.

To give new rosemary a head start on surviving next and future winters, here’s what the National Arboretum experts suggest: Plant new rosemary in a location that gets full sun throughout the year, in a site sheltered from winter wind, if possible. Plant in the spring so the roots have a good, long time to become established. If your soil is a heavier clay type, mulch with gravel to reflect light and heat back into the plant and help prevent soil-borne diseases from splashing onto the leaves.

New book: Troy Marden says ‘Plant This Instead!’

Plant This InsteadMiddle Tennessee garden guru Troy Marden believes there are better choices than some of the same old plants we reach for at the nursery time after time. His new book, Plant This Instead! is out now (published by Cool Springs Press), and Troy is giving a free lecture and book signing next Saturday (April 12) at Moore & Moore Garden Center, 1826 Highway 100 in Nashville. He’ll be there 10 a.m. – 2 p.m.

More on the book later. Meanwhile, I’m flipping through the copy I have here and looking for alternatives to replace some of those shrubs and perennials that bit the dust this winter.

Cheekwood’s a winner!

A few weeks ago I noted that Cheekwood Botanical Garden & Museum of Art was one of the finalists for BestPublicGarden in USA Today Travel’s 10Best Readers’ Choice Awards list.

The votes are in, and among the 10 winners (determined by a public vote), Cheekwood placed 6th on the list.

“We are absolutely thrilled to be included in the list of 10Best Readers’ Choice Travel Award winners,” said Cheekwood president Jane O. MacLeod in a press release announcing the results. “Being chosen by the public to win this award is a big honor— and it proves that Cheekwood ranks among some of the most celebrated and well-known gardens in the world.”

The results were determined by supporters who voted at the 10Best Readers’ Choice Award web site. “We are so grateful to everyone who voted for Cheekwood, both for their support and for helping us earn even more wonderful exposure,” McCleod said. Congratulations, Cheekwood!