• Enter your email address to follow this blog and receive notifications of new posts by email.

  • Upcoming Garden Events

    Sept. 30: The Nashville Herb Society presents Through the Garden Gate: A Glimpse of Edwardian England, 8 a.m. – 3 p.m. at Cheekwood Botanic Hall. Celebrate the gardens, foods and flowers that delighted Downton Abby family and friends at the turn of the 20th century. The event begins with a hearty Edwardian breakfast, followed by three speakers: Marta McDowell on Beatrix Potter’s Gardening Life; Geraldine A. Laufer on Tussie Mussie – Victorian art of expressing yourself in the language of flowers; and Terry White, The English Garden event florist . Registration includes breakfast, box lunch in the garden with music, English tea and cookies. To learn more or to register, visit www.herbsocietynashvlle.org.

    Tips & tasks – September

    Cut the dead tops of coneflowers, but leave enough for goldfinches to enjoy the seeds.

    Plant cool-weather vegetables for a fall crop: spinach, mustard and turnip greens, radishes, leaf lettuce.

    Start a new lawn of cool-season grass, such as fescue, or refurbish or repair establish lawns.

    Don’t let the soil of newly planted grass dry out. New grass needs about an inch of water per week.

    It’s still warm, so continue to water and weed garden beds as needed.

    Remove dead foliage, spent flowers and other garden debris; replenish mulch as needed.

    Continue to harvest produce, which may be getting a boost now from slightly cooler weather. Keep watering sage, rosemary and other perennial herbs so they’ll be in good shape to get through winter.

    Prepare to bring houseplants back indoors: remove dead leaves, scrub soil from the sides of the pots, treat for insects. Bring tropical plants in before nighttime temperatures dip to 55 degrees.

  • Categories

  • Archives

Too early for tender hostas

Because it has been so warm already, my hostas have been coming up much too early, and I’m afraid they’ll be damaged or killed if we have another freeze. Some are in pots and some are in the ground. What’s the best way to protect them?

hosta shoots

Hosta shoots are difficult to see when they emerge, but they should be protected from a freeze.

You are correct that hostas making an appearance too soon would be damaged by frost or a freeze, so it pays to watch the forecast and take action when the temperature drops. Cornelia Holland, a hosta collector in Franklin, Tenn., grows hundreds of hostas and other shade-loving perennials in a half-acre garden she calls “Tranquility.” She passed along these tips for keeping hostas healthy when they emerge too soon. Continue reading

Advertisements

Summer is hard on the lawn

QUESTION: Our lawn has looked great all summer – until now! The grass is turning brown in patches, even though I water it regularly. What’s wrong?

Grass brown patchFor lawn-lovers, the middle of summer often brings disappointment to those who carefully cultivate that carpet of green. I’ve written about the problem here before, but here at mid-summer, it bears repeating.

In Middle Tennessee (Zone 7A, where The Garden Bench calls home), fescue seems to be the preferred type of lawn. It’s a cool-season grass, and it has a tendency to go dormant and turn brown when the weather is hot and dry. It often perks up again when the weather gets cooler.

But lawns can also suffer from brown patch, a fungal disease that can affect fescue lawns. It starts with small brown patches, or a ring of brown grass that gets larger over time. The plant may be green at soil level, but individual blades of grass will be brown.

Before you resort to a fungicide, it’s a good idea to know exactly what the problem might be. I’m not a lawn expert, so when I wrote about this before, I pointed to the popular garden guru and author Walter Reeves’s web site, which provides quite a bit of information about lawn fungus, blights and molds. Here it is again.

In general, lawns do well with about an inch of water a week. They don’t need to be watered every day, but water deeply about once a week if it doesn’t rain. It’s also a good idea to cut the grass higher; when grass is cut too short, it leaves the lawn vulnerable to more weeds and diseases.

Protect banana trees from the cold

'Texas Star' banana. Photo by Dave G.

‘Texas Star’ banana. Photo by Dave G.

We planted a new ‘Texas Star’ banana tree this spring. It’s growing and looks great, but how do we protect it this winter? We live in Middle Tennessee, and it is planted in an open area near a pool.

The ‘Texas Star’ banana is said to be a cold-hardy variety, but it still needs coddling over the winter here in Zone 7a, where temperatures regularly fall below freezing. Once they’re exposed to a couple of frosty nights, the leaves will be reduced to a wilted mush. The important thing is to protect the underground rhizomes. The University of Tennessee Institute of Agriculture grows an impressive Hardy Banana in the UT Gardens in Knoxville, and provides this information for overwintering a banana plant:

Just before frost is expected, use a clean, sharp saw to cut the stems and leaves down to about 8 – 10 inches above the ground, then pile a thick layer of mulch over the crown. They say it’s best to use a heavy mulch (pine bark or hardwood), which won’t blow away easily. Others suggest you cover the stump with the leaves you cut from the plant, or wrap the stump with a blanket, and cover it with an overturned plastic garbage can.

In the spring, remove the mulch after the danger of frost is past, and the rhizome will send up new shoots and grow rapidly when the weather has warmed.

By the way, in this area banana trees are grown for their exotic foliage; it takes a long time to grow bananas, and summer here just isn’t long enough (though if you’ve grown bananas here in Zone 7a, I’d love to hear from you!).

Powdery problems

I have three peonies. Two are fine, but the third, in a different location, is completely covered with powdery mildew. How does that happen? Should I do something about the one that’s covered? Or just leave it and hope for the best?

Powdery mildew (which affects all kinds of plants in the landscape) can be a problem when weather conditions are right and cultural conditions are less than perfect. It’s a fungus that thrives in warm weather when the humidity is high. It becomes more of a problem for plants that are growing in damp, shady places and overcrowded conditions.

It’s a common disease and you’ll know when it hits: look for patches of gray-white, powder-like growth. It usually appears on the tops of leaves but can also be seen on the bottoms of leaves, and on young stems, buds and flowers. It likes the young, succulent parts of plants.

At the UT Extension Soil, Plant and Pest Center, expert Alan Windham (who frequently provides answers to questions here) says the peony should survive with no problem. It’s a good idea to remove any dead or dying foliage and destroy it (don’t put it in the compost; that probably won’t kill the fungus spores), and clean up around the area.

Windham is more worried about downy mildew in beds of impatiens, which we mentioned in this column several weeks ago. “There are lots of cases coming in from all over the state; it’s been found in nearly every state east of the Mississippi,” he says.

Watch for plants that are losing leaves, that don’t flower, and that have white growth on the undersides of the leaves, he advises. The disease can be extremely damaging, so pull up, bag and dispose of infected plants to keep it from spreading.

Bad news this year, but even bigger implications for next year regarding availability, use by commercial landscapers and their general viability as a bedding plant, he said. Does that mean the ubiquitous impatiens won’t be among the gardener’s favorite go-to shade annual next year?

“Begonias, SunPatiens and New Guinea impatiens are going to be in high demand,” he says.

If you haven’t seen the Soil, Pest and Plant Center’s Facebook page, check it out here. “We’re putting lots of good stuff up,” Windham says.

 

Too hot to bloom!

QUESTION: I have a pot of impatiens that was doing well, but now the flower buds have been dropping off or turning brown before opening. The pot is always in the shade and I keep it well watered and fed. It has nice green leaves, just no flowers. Any idea what could cause this?

If there are no other symptoms – no spotting of the leaves, no rotting of the stems, no powdery coating or other unusual growth – a good guess at the source of the problem would be the long period of extreme heat. Even in the shade it has been extremely hot (remember that day it hit 109 degrees?) and plants in containers may suffer more because the pot can dry out quickly. A plant under stress will shed its flowers first.

By now, with several days of rain and more reasonable temperatures, the impatiens (and many other things) should begin to recover.

This is a good time to mention again, though, an email I received from UT Extension plant disease expert Alan Windham, in which he warned about the development of downy mildew in beds of impatiens. Watch for plants that are losing leaves, that don’t flower, and that have white growth on the undersides of the leaves, he advises. This disease can be extremely damaging, so pull up, bag and dispose of infected plants to keep it from spreading. There’s more about it at UT Extension’s Soil, Pest and Plant Center Facebook page.

…And too hot to plant, too

QUESTION: My daughter has thinned out her iris bed and given some to me.  She has given me the whole plant (bulbs and stems). I know I can not plant them at this time but how do I store them until they can be planted in November or December?  Do I need to cut the stems off now or leave them as is?  Thanks for any information you can provide. 

You’re right, with too much heat and still too little rain, it’s a bad time to plant anything. Irises are pretty hardy so you can wait to plant the rhizomes.

For now, cut the leaves off to about 3 to 6 inches, and remove as much of the soil from the rhizome as you can. Don’t wash them, just brush off the dried soil. Check to make sure there are no rotting places, insects or diseased-looking spots (discard those if there are) and store them in a cool, dry place.

You don’t need to wait until November to plant them. While they’re pretty hardy, they’d still rather be in the ground, so consider planting in September, or after the worst of the summer heat passes.

When you do get ready to plant, here’s a helpful link from the American Iris Society that provides information.

Another reminder about watering: In spite of all the rain lately, we’re still experiencing severe drought conditions in Middle Tennessee. Young trees suffer most. If you planted trees this spring, give them a little extra attention to help them make it through this hot, dry summer. Click here to see the Nashville Tree Foundation’s guidelines and tips to help keep your trees healthy.

The drought takes a toll on trees

QUESTION:  I have a concern about two hackberry trees in my yard. They are quite old and beautiful, but the leaves are turning yellow and are falling off rapidly.  Is this due to the high heat or another problem? I would sincerely hate to see these lovely trees die.  

During drought, a hackberry’s leaves may turn yellow and fall. Mature, healthy trees should recover.

Let’s just say that while the high heat is a major culprit in the early-summer yellowing of a lot of things, it’s not acting alone. “It’s drought primarily,” says Alan Windham, the ornamental and turfgrass pathology expert at U.T. Extension.

“I actually witnessed this, this morning on hackberry behind my home while walking my dogs,” he said when I sent him this question earlier this week. “It was breezy, and yellow leaves were falling from the hackberry like a fall day.”

Most likely, this leaf-fall is not a fatal condition. “Most mature trees have survived many droughts, and should be able to survive this one,”Windham said. “Regardless, I’m hoping for rain this week.”

Young trees that haven’t had a chance to develop an extensive root system are more vulnerable. An email alert from the Nashville Tree Foundation, which plants trees in public places and private yards on its ReLeafing day each November, has sent an alert with watering guidelines and new tips that you can read here to help young trees survive. Most important: water thoroughly, and water slowly to prevent run-off.

The long-range weather forecast may show some relief. Next week, it looks like temperatures will be in the more reasonable mid-to-upper 80s, with a chance of rain.

 

Spider mites like it hot. Watch your roses

QUESTION: 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.

Keep an eye on roses when it’s hot and dry. Spider mites can turn a lovely rosebush into an ugly mess.

This time of year, with this kind of weather, suspect spider mites, which thrive when the weather is hot and dry, say rosarians at the Nashville Rose Society. 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.

Record heat is trouble for trees

Meteorologist Bobby Boyd sends me email from time to time about extreme weather conditions. The latest concerns the large dome of high pressure building eastward out of the plains and across the Tennessee Valley that has put Middle Tennessee, as he says, “in the pressure cooker.” We’re breaking records this weekend. No rain in sight, and gardens are suffering.

Young trees and shrubs are especially vulnerable. The Nashville Tree Foundation has sent an alert with watering guidelines and new tips that you can read here to help trees survive.

Keep these tips handy. It’s still only June, and we’ve got a long way to go.