July 2010

Weather encourages blight on Indiana lawns

Pythium blight makes it easy to pull dead grass from the soil. Photo courtesy Cornell University

Pythium blight makes it easy to pull dead grass from the soil. Photo courtesy Cornell University

Environmental factors the last two months have been perfect for pythium blight, which seemingly overnight creates splotches of brown, dead grass. The heat and humidity mixed with the rain causes this fungus to show up usually in low-lying areas, shallow depressions or swales in the lawn.

“This disease is most common during hot, very humid weather. The disease can spread rapidly, killing large areas of seedling or established turf in as little as a day during conditions of high temperatures, high soil moisture and little air movement over the turf,” say Cornell University turf experts.

If conditions are right and nothing is done to curb the disease, large patches of lawn will be killed. It is particularly bad on perennial rye, but if severe, can infect bluegrass and fescues, too, although these are generally more resistant, Purdue University turf experts say.

The pythium fungus winters over in the soil and, when environmental factors align, is activated by water movement, which is why low-lying areas are most affected.

For the homeowner, the use of fungicides is considered a last resort, and only if the disease has shown up two years in a row. Purdue recommends contacting a lawn service for the fungicide treatment, which may require a license to apply.

Instead, turf experts recommend cultural controls: improving drainage in low lying areas, removing the lower limbs of trees to increase air circulation and delaying mowing until the grass is dry. Avoid high nitrogen fertilizers and watering the lawn in late afternoon or evening. Pull up the dead lawn and reseed or over seed with Kentucky bluegrass.

For more info on pythium blight:

Cornell University

Purdue University

Virus attacks cannas, reduces supply

Canna 'Ehemanii' from Old House Gardens

Canna 'Ehemanii' from Old House Gardens

In his latest newsletter, Scott Kunst, the bulb czar at Old House Gardens, says he’s going to stop carrying all but one canna because of a virus that has infected crops worldwide.

“Although we love them, and we’ve worked hard to preserve and share the best of them with you, we’ve decided to stop selling cannas — at least temporarily.

“A new virus has been attacking cannas worldwide in recent years, and despite herculean efforts by our expert American growers, we’ve become troubled by what we’ve started seeing in our trial gardens and hearing from our customers.

“You come to us for great bulbs, and that’s exactly what we want to send you. When we can once again be sure that every canna we ship is superbly healthy, we’ll return them to our catalog — and celebrate! But right now that’s beyond our reach.

“There is one canna we’re still offering — ‘Ehemanii’. It’s the only one grown for us in a tiny nursery in Texas, and it’s still as healthy as can be.

“And we’re not abandoning our other rare cannas altogether. With an eye to the future — and the possibilities that tissue-culture offers — our indomitable Missouri grower will continue growing the best of them as scientists, farmers, and enthusiasts around the globe search for solutions.

“Coming to this decision has been a painful process. Our mission, after all, is to ‘Save the Bulbs,’ and we feel for our growers. But we’re convinced it’s the right decision.

“If any of the cannas we’ve sent you developed streaked, mottled, or twisted leaves, we recommend that you destroy them and please let us know so we can give you a credit or refund. Then together we’ll look forward to brighter days ahead for cannas and those who grow and love them.”

The new catalog (Fall 2010/Spring 2011) is on the Web site.

Hosta plant sale features expert advice for shade gardening in Indiana

August 8, 2010
8:00 AMto3:00 PM
<p>Shade garden with hosta, astilbe and hydrangea. (C) Jo Ellen Meyers Sharp</p>

Shade garden with hosta, astilbe and hydrangea. (C) Jo Ellen Meyers Sharp

F.C. Tucker Parking Lot, 1119 Keystone Way, Carmel, Ind., the Indianapolis Hosta Society’s annual plant sale features more than 100 varieties of this shade-loving plant, including rare and unusual cultivars, classic favorites, minatures and giants. Also for sale will be companion plants for the hosta garden, which include coral bells, daylilies, grasses and more.

Also on hand will be hosta experts and experienced shade gardeners.

Funds from the sale support community service, such as the society’s planting at the entrance of Holliday Park, and educational projects. Transactions in cash or check only.

For details, please visit the society’s Web site.

Give plants a midsummer makeover

'Evolution' salvia is ready to be deadheaded. (C) Jo Ellen Meyers Sharp

'Evolution' salvia is ready to be deadheaded. (C) Jo Ellen Meyers Sharp

By now, many of summer’s flowers look a bit bedraggled. On Indianapolis Fox 59 Morning News July 28, the Hoosier Gardener offers tips for giving plants a midsummer makeover.

Heat, humidity and rain have challenged the landscape this year. This environment may cause annuals to be excessively stretched over the edges of containers or sprawling in the landscape developing smaller and smaller flowers as they grow.

Perennials that have stopped blooming may have brown stems where flower used to be. Cutting off spent flowers, called deadheading, frequently  encourages more blooms on perennials and annuals, and it also tidies up the plants.

With all of the rain we’ve had, plants may be starved for food, especially annuals in containers or in the ground. Give them a good dose of bloom-booster fertilizer, compost tea or other nutrients, according to label directions.

In the vegetable garden, make sure to keep harvesting the produce. Produce harvested at the right time ensures the best flavor and encourages the plant to keep producing more food.

Make sure to keep weeds out of the gardens because they rob food and flowersing plants of water and other nutrients.

Clematis wilt turns vine brown or black

Clematis wilt afflicts flowering vine. (C) Shirley Remes

Clematis wilt afflicts flowering vine. (C) Shirley Remes

Clematis is one of the most popular perennial vines in the landscape. The plant has  large or small star-shaped or bell-shaped flowers, depending on the cultivar. The cultivar also determines when the clematis blooms — off and on all summer or only at specific times, such as spring or fall.

The favorites are the large flowering types, including ‘Superba,’ ‘Nelly Moser’ and ‘Rogue Cardinal.’ However, many of these lovely vines are susceptible to clematis wilt (Ascochyta clematidina), a soil-borne fungus disease that sometimes creeps up from the base or sometimes strikes right at the center of the plant. The suddenly wilts, turns brown or black and the leaves dry up.

A fungus disease causes a Clematis vine to wilt. (C) Shirley Remes

A fungus disease causes a Clematis vine to wilt. (C) Shirley Remes

Although a common, opportunistic disease on Clematis in Indiana gardens and elsewhere, fortunately, the wilt does not usually kill the plant. The remedy is to cut out the damaged area to the ground and remove from the soil any leaves that fall from an infected plant. More vines will grow from the roots and the plant will likely recover in a year or two. A chemical treatment is not recommended.

Over the last few years, several clematis cultivars have been introduced by the English breeder Raymond Evison, which  are considered resistant to the wilt disease.

There are three types of clematis and knowing which one you have will help with the always-puzzling pruning questions.

Group 1 — includes many of the alpines, which have smaller flowers. These bloom on year-old growth, so no pruning is required unless it is to control size.

Group 2 — blooms on current season growth and year-old growth. Prune in early spring as needed for shaping or to remove winter damaged or dead growth. This group includes ‘Nelly Moser,’ ‘Niobe’ and ‘Multi-Blue.’

Clematis 'Jackmanii.' Photo courtesy

Clematis 'Jackmanii.' Photo courtesy

Group 3 — blooms on new growth, so it can be cut back to 10- to 12-inches from the ground in early spring. This group includes C. jackmanii ‘Superba’ and ‘Comtesse de Bouchaud.’

Here are some more resources:

Ohio State University Growing Clematis

American Clematis Society

Scott Arboretum

Purdue University

Tips for Tending Your Garden – Fox59

Not Too Late to Plant Vegetable – Hoosier Gardener on Fox59

Garden Tour Tips – Hoosier Gardener on Fox59

Hydrangea primer: what to prune when, why and how in the Indiana and Midwest garden

Quick Fire is one of the first Hydrangea paniculatas to bloom. Photo courtesy Proven Winners/ColorChoice

Quick Fire is one of the first Hydrangea paniculatas to bloom. Photo courtesy Proven Winners/ColorChoice

About this time last year, I wrote a piece for Angie’s List Magazine (see below) about hydrangeas, including tips on growing and pruning them.

Tim Wood, who hunts plants for Spring Meadow Nursery in Grand Haven, Mich., has published another hydrangea primer that many Indiana gardeners will find helpful, too. Known as the Plant Hunter, Wood’s latest newsletter talks about growing hydrangeas in the Midwest and offers some great pruning tips for those desirable big-leaf and re-blooming hydrangeas (Hydrangea macrophylla).

He reminds us that the most reliable hydrangeas for most of the Midwest are the native Hydrangea arborescens, of which the white mophead ‘Annabelle’ is probably the most familiar. ‘White Dome,’ with delicate, white lacecap flowers, also is a H. arborescens. ‘White Dome’ is a Spring Meadow introduction, which is marketed under the Proven Winners/ColorChoice brand. The nursery also introduced ‘Invincibelle Spirit,’ the first pink-blooming Hydrangea arborescens.

You just can’t beat the panicle hydrangeas (H. paniculata) for reliability, beauty and ease of care. The popular and best selling ‘Limelight’ is another Spring Meadow introduction. Two other stunners are Pinky Winky and Quick Fire.

Angie’s List article

We’re heading in to high season for hydrangeas, one of the showier shrubs in the landscape. With their moptop and lacecap flowers, these plants grab centerstage in the summer garden. And, they hold a place for two more acts as their flowers dry to autumn hues, then winter whites.

There are two basic types of hydrangeas (Hydrangea), those that bloom on year-old growth and those that bloom on current season growth.

The big-leaf hydrangea (H.  macrophylla) forms its flower buds in late summer and fall. In the upper Midwest and other cold climates, freezing temperatures in late spring frequently zap these buds, causing the plant to grow leaves, but no blooms.

You can reduce this threat by siting a big leaf hydrangea where it is buffered from drying winds and freezing temperatures. Many northern gardeners protect it by making a sleeve to fit around the plant and filling it with leaves in fall. The leaf-stuffed sleeve stays on the plant until spring, when there’s no danger of a hard freeze. The sleeve can be made of cloth, such as burlap, or it can be a plastic trash can with the bottom cut out.

The big-leaf hydrangea is better suited for the more moderate climates in the West, South and Southeast. H. serrata is another popular hydrangea that blooms on year-old growth and can be susceptible to flower bud damage from cold temperatures.

If you need to prune these hydrangeas, or the native oakleaf hydrangea (H. quercifolia), do so within a month after it blooms. Although the oakleaf blooms on year-old growth, it does so later in the season so its flower buds are less likely to be damaged by late spring temperatures, making it more reliable in northern gardens.

Breeders have begun marketing big-leaf hydrangeas that bloom on new and old growth. Endless Summer™ is probably the best known in this new breed.

The color of the flowers on H. macrophylla depends on the soil. Acidic soil produces flowers in the blue range and hydrangeas planted in alkaline soil have blooms in the pink palette. You can add alumninum sulphate to hydrangeas planted in alkaline soil to turn them blue and lime to those planted in acidic soil to turn them pink.

The most reliable selections for cold climates are the native smooth-leaf hydrangea (H. arborescens) and H. paniculata, commonly referred to as peegee hydrangea, from Asia. Both of these hydrangeas bloom on current season growth, which means you can prune them in spring without cutting of summer’s flowers. The flower colors on these hydrangeas cannot be altered by soil additives. These bloom on current season’s growth — what grows this year blooms this year.

Prune H. arborescens to the ground in late winter or early spring. Prune H. paniculata as needed as needed for shaping or cleaning up damaged branches in late winter or early spring.

Popular smooth-leaf hydrangeas are the mop-top ‘Annabelle’ and the lace-cap ‘White Dome.’ Invincebell Spirit, another breeding breakthrough, is the first pink-blooming H. arborescens moptop. It will be marketed under the Proven Winners ColorChoice brand in spring of 2010.

‘PeeGee’, ‘Tardiva’, ‘Grandiflora’, ‘Pinky Winky’, Quickfire and ‘Limelight’, are good choices for H. paniculata. These form cone-shaped flowers, called panicles, that take on various hues of white, green or pink. These tolerate more sun that other hydrangeas.

Plant hydrangeas in shade to part sun. They tolerate full sun, but will need supplemental watering. All hydrangeas do best in soil rich in organic matter. The native smooth-leaf hydrangea can handle fairly wet soil to dry.

Apply about an inch of compost, rotted manure or other organic matter to the soil around hydrangeas in spring as they start to develop their leaves. If using a soil additive or hydrangea fertilizer, always read and follow the label directions.


It’s the heat AND the humidity taking a toll in Indiana gardens

<p>Curling leaves do not always mean a plant needs to be watered. (C) Jo Ellen Meyers Sharp</p>

Curling leaves do not always mean a plant needs to be watered. (C) Jo Ellen Meyers Sharp

It’s painful to watch our plants struggle in the smothering heat and acting on our instinct can cause more problems than we cure.

Plants respond to hot weather or the lack of water in similar ways. The leaves curl, turn upside down or flatten close to the plant stem. The plant is trying to conserve moisture by reducing the parts exposed to the sun and heat.

We see this reaction on many, many plants, including trees, shrubs, flowers and food crops. Hydrangeas, impatiens, tomatoes and coneflowers are just a few examples.

Unfortunately for the plants, we respond to these symptoms with the same treatment — water, water and more water and end up drowning the plant’s roots or causing top growth to rot off.

We should water only if we know the plant needs water. If a plant’s leaves return to normal when out of the sun or during lower night temperatures, they probably don’t need water.

Another test is to check the soil. For large plants, such as shrubs and perennials, stick a trowel, spade, knitting needle or soil probe into the ground. If the instrument comes out with damp soil, don’t water. If the instrument comes out dry, water deeply.

For smaller plants, such as annuals in the landscape or in pots, rely on your index finger. Stick your finger in the soil and if it feels dry to the second knuckle, water.

Containers should be watered until the water runs from the bottom. Sometimes containers dry out completely and water drains immediately from the pot without dampening the soil. Place the pot in a bucket or tub of water to allow the soil to wick up the moisture. Or, place some ice cubes on the soil surface, away from the stems of plants. The soil is re-moistened slowly by the melting ice.