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August 2015
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Downy mildew attacks basil

Downy mildew has taken a toll on basil the last few years. One symptom is fuzzy spores on the undersides of leaves. Photo courtesy Purdue Plant and Pest Diagnostic Lab

Downy mildew has taken a toll on basil the last few years. One symptom: fuzzy spores on the undersides of leaves. Photo courtesy Purdue Plant and Pest Diagnostic Lab

Basil has taken a huge hit over the last few years from a downy mildew, which can quickly decimate a crop in the farmers’ fields, growers’ greenhouses and our gardens.

Downy mildew is the common name for this disease, even though the fungus that causes it may be different, depending on the plant. It gets the name from the symptoms, downy-like fuzz on the leaves.

On basil, the culprit is Peronospora balbahrii. Initially, the leaves turn yellow, and then black spots appear. That’s followed by fuzzy spores on the undersides of leaves. The problem starts at the base of the plant and moves up. The fungus is air borne or can be splashed on plants from infested soil. Plants and seeds can be infected, according to the University of Minnesota Extension, which got its first reports of the disease in 2012.

Here in Indiana, Purdue University has seen only a handful of samples since 2009. “A couple each year,” said Tom Creswell, director of Purdue’s Plant and Pest Diagnostic Lab.

“Most of our reports from the home garden have been from the home garden of Tom Creswell,” he joked. “It seems that if this is showing up extensively in the home garden, then either no one is paying attention or it comes on so late in the season that they’ve already made pesto, or they don’t know they can send samples to the lab for help.”

What can we do?

  • Remove any infested leaves. It’s all right to eat healthy leaves from infested plants.
  • Plant resistant varieties. Sweet basil (Ocimum basilicum) is the most susceptible, which includes Genovese, Nufar, Italian Large Leaf, Queenette, Superbo, Poppy Joe’s and others, according to Minnesota extension. Red Rubin and Red Leaf (O. basilicum purpurescens) and lemon basils (O. citriodorum) are considered moderately susceptible. Blue Spice, Spice, and Blue Spice F1 (O. americanum) are less susceptible.
  • Don’t plant basil in the same spot year after year. If you grow basil in a pot, dump the soil each year and scrub the pot with a solution of one part bleach and nine parts water. Use fresh potting mix each year.
  • Give plants plenty of air circulation.
  • Closely examine basil plants at garden centers to make sure they are symptom free.
  • Consider growing basil from seed. It’s easy and plants comes up quickly.

Lilac trees extend the fragrant season

Lilac tree flowers are as fragrant as their shrub cousins. (C) Jo Ellen Meyers Sharp

Lilac tree flowers are as fragrant as their shrub cousins. (C) Jo Ellen Meyers Sharp

At garden centers, on garden tours, over dinner and in emails, people are asking about a tree with fragrant white flowers.

It’s a Japanese lilac tree (Syringa reticulata), a gorgeous beauty that blooms later than lilac shrubs. The ornamental tree has a rounded to pyramid form and reaches 30 feet or more tall and 20 feet wide. It is considered one of the easiest lilacs to grow.

The 12-inch long, creamy white flowers bloom in June, attracting butterflies, hummingbirds, pollinating insects and human attention. Cardinals, chickadees and finches like the seeds. The tree tolerates clay soil, deer browsing and salt spray.

Japanese lilac tree does best in full sun but tolerates light shade, which may reduce blooms. It needs decent drainage and is considered a good urban tree. You’ll see it planted as a street tree in several Indianapolis neighborhoods, along the Indiana Central Canal, the city of Carmel and other communities. It also makes a lovely hedge, windbreak or seasonal screen.

Good air circulation is recommended, even though the tree is considered resistant to powdery mildew, the plague of many shrub lilacs. It also is resistant to scale and borers, other pests of lilacs. If the lilac tree needs to be pruned, do so within a month after it is done blooming.

There are a couple of cultivars, but ‘Ivory Silk’ is the most widely available. More compact, ‘Ivory Snow’ gets up to 25 feet tall and is a profuse bloomer, usually a little earlier than the straight species of Syringa reticulata.

The seed capsules dry and are abundant enough to provide a bit of fall interest. The smooth, attractive, reddish-brown bark resembles a cherry tree.

For more information about the lilac trees and shrubs, download Lilacs for Cold Climates, a very helpful, free publication by Laura Jull, a horticulture professor at the University of Wisconsin.

Trees and shrubs to consider for your landscape

Native Virginia bluebell form a carpet of blue beneath the yellow Japanese Kerria. (C) Jo Ellen Meyers Sharp

Native Virginia bluebell form a carpet of blue beneath the yellow Japanese Kerria. (C) Jo Ellen Meyers Sharp

If I could only have one perennial for certain situations, such as shade or sun…that’s what we talked about in last week’s column. This week, we’ll look at a few shrubs and trees.

First up is viburnum, a species that has a shrub for about any location. There are several native viburnums that are garden worthy, including arrowwood (V. dentatum) and the American cranberry bush (V. opulus var. americana), sometimes listed as V. trilobum).

But my favorite is burkwood viburnum (V. x burkwoodii), a large, semi-evergreen shrub with fragrant, pinkish-white, waxy flowers in April and respectable leaf color in fall. Although burkwood does best in full sun, mine has been in part sun for years and does just fine. It gets about 8 feet tall and 6 feet wide. The size and the fact that it holds onto its leaves well into winter, make it a good choice for a three-season screen. It is drought tolerant and attracts butterflies and birds. The latter likes the showy fruit, which is not messy.

For deep shade, consider a kerria, sometimes called Japanese yellow rose (K. japonica). My preference is the single flowering kerria, called ‘Simplex’, but there’s a double flowering yellow (‘Pleniflora’) and single white one, too (‘Alba’). In my yard, the kerria gets early morning sun and blooms the same time as my Virginia bluebells (Mertensia virginica) to make a beautiful spring scene.

Kerria does not do well in full sun, which bleaches out the flowers. Arched chartreuse branches brighten the winter landscape. At maturity, it will get 3-6 feet tall and wide, suckering a bit to develop a colony. The suckers can be removed to keep kerria the right size for your space. It tolerates clay soil, dry and wet sites and deer. The flowers are about the size of a quarter and it’s not uncommon for kerria to rebloom in late summer. ‘Golden Guinea’ is slightly smaller than the species.

For a shade tree, I select a thornless honey locust (Gleditsia triacanthos var. inermis) for lots of reasons. The native tree provides dappled shade, which allows grass to grow underneath. The small ferny leaves also blow away in fall, reducing raking duties. This tree can become a problem if the roots are cut or removed, which can promote the growth of sprouts. There are several honeylocust cultivars available. At maturity, the tree will be 30 to 70 feet tall and wide.

If I could only have one perennial for these spots

Epimedium. (C) Jo Ellen Meyers Sharp

Epimedium. (C) Jo Ellen Meyers Sharp

I get asked a lot of the time what my favorite flower is and my response is “whatever is blooming.”

But what if you could only have one of something, what would your choices be? Here are some of my picks:

Hydrangea – the oakleaf (H. quercifolia) would be my choice, but most are very large shrubs, usually in the 6-8 foot tall and wide range. That size is fine for larger properties. Because I have a small yard, I prefer Sike’s Dwarf, Pee Wee or Ruby Slippers, which are closer to 3-5 feet tall and wide.

Native in the southeast United States, oakleaf does best in part shade or dapple shade, but tolerates full sun if given adequate water. It begins blooming in June with white cone-shaped flowers that turn red as they age through the season. The leaves turn a deep, wine red in fall and persist through winter.

Sike's Dwarf oakleaf hydrangea. (C) Jo Ellen Meyers Sharp

Sike’s Dwarf oakleaf hydrangea. (C) Jo Ellen Meyers Sharp

Bishop’s cap (Epimedium), commonly called barrenwort or bishop’s cap, is my choice for a shade-loving perennial. This is nearly a four-season plant, beginning with delicate, wiry flowers in early spring, followed by reddish-tinged, leaves. The leaves are dark green in summer, and in fall, become leathery, deep maroon. I cut this plant back to the ground in February. Epimedium thrives when given adequate moisture, but is tolerant of dryer sites. Start with two vigorous (but not invasive) cultivars: the yellow-blooming (E. x versicolor ‘Sulphureum’) and red (E. x rubrum).

'Magnus' purple coneflower (Echinacea purpurea). Photo courtesy perennialresource.com

‘Magnus’ purple coneflower (Echinacea purpurea). Photo courtesy perennialresource.com

Purple coneflower (Echinacea purpurea) would earn space in a sunny spot. Another eastern United States native species, this long-blooming perennial is favored by bees, butterflies and hummingbirds in summer and in winter, the finches devour the seed heads. There are a lot of garden-worthy cultivars available, but to me, the best performers are the straight species or ‘Magnus’. Somewhat drought tolerant, purple coneflower appreciates a good soaking of water during dry periods. Coneflowers are usually 24-30 inches tall and form a clump about 12-inches wide. They can self-sow a bit, but are not invasive.

High season for garden tours

Twin Oaks’ garden has been lovingly restored and rebuilt by John Herbst, president of the Indiana Historical Society, who resides in the home. Photo courtesy Indiana Historical Society

Twin Oaks’ garden has been lovingly restored and rebuilt by John Herbst, president of the Indiana Historical Society, who resides in the home.
Photo courtesy Indiana Historical Society

Put on your walking shoes, slather on some sunscreen, grab an umbrella and a hat and head outdoors, for this is the season of garden tours. Most of the tours benefit the neighborhoods, garden clubs, education programs and other projects by the sponsoring groups.

Garden tours are rich with ideas for crafting your own landscape, examples of knockout plant combinations and exposure to plants you never heard of. Here’s a round up.

Historic Meridian Park, noon to 6 p.m., May 30 and 31. Start at Trinity Episcopal Church, 3243 N. Meridian St.

The 20th annual Indianapolis Garden Club Garden Walk, 9 a.m. to 3 p.m., June 3, five gardens.

Twin Oaks Home and Garden Tour, June 5 through 7. Built by L.S. Ayres, this was the late Ruth Lilly’s residence and garden, which is now leased to the Indiana Historical Society.

Meridian Kessler Home-Garden Tour, June 6 and 7. Seven homes and gardens are on the tour. This event is more about the homes than the gardens.

Gardens of Zionsville, 10 a.m. to 4 p.m., June 20. Includes summer tablescape ideas and an opportunity to bid on containers planted by area vendors. Number of gardens not specified.

Plainfield Garden Club Tour, June 20 and 21 features seven gardens.

11th annual Brownsburg Garden Tour, 10 a.m. to 5 p.m. Saturday, June 27 and 11 a.m. t 4 p.m., Sunday, June 28. Five gardens. Details: Tia Foundation, 317-852-3463.

Irvington Garden Tour, 1 to 5 p.m., June 28. Number of gardens not specified.

Woodruff Place Home and Garden Tour, June 27 and 28. Six homes and four gardens.

Now that you’re decked out and ready to go, here are some tips to make your tours enjoyable, comfortable and with the best etiquette.

  • Wear comfortable shoes. You may be walking on muddy pathways or gravel walkways.
  • Anticipate the weather and dress appropriately.
  • Stay on the pathways. Wandering off the paths of a garden is like open a closed door in someone’s house.
  • Do not take anything except notes and photos. No filching seeds, cutting flowers or taking snippets of plants allowed. There are horror stories from garden tour hosts who have had whole plants stolen from their gardens.
  • Think green. Don’t leave any trash or litter.
  • Allow time to enjoy the gardens. Remember some may be crowded, so be sure to take time to smell the roses.

 

 

Onions for the flower garden

Alliums adorn the spring garden. (C) Jo Ellen Meyers Sharp

Alliums adorn the spring garden. (C) Jo Ellen Meyers Sharp

Every spring, I’m always a bit surprised by the ornamental onions that pop up amid the oakleaf hydrangea in the front garden.

For weeks, I’m under the spell of daffodils, tulips, Virginia bluebells, snowdrops and other spring bulbs. But as these wane, perennials come to the fore, including columbines (Aquilegia), creeping phlox (P. subulata), woodland phlox (P. divaricata), soapwort (Saponaria) and lungwort (Pulmonaria).

I think the ornamental onion (A. giganteum) escapes my notice until it blooms because the foliage is camouflaged by the oakleaf hydrangea (H. quercifolia). These bulbs came from a friend and, of course, I always think of her when the alliums bloom.

Alliums are among the trendy plants right now, primarily because many of them bloom in mid summer, when there’s a little bit of a lull in the garden. Ornamental onion is planted in fall along with other spring blooming bulbs. Last fall, I planted 100 summer-blooming allium (A. carinatum pulchellum and A. sphaerochephalon) in large clusters in several garden beds.

In late May and June, you might be able to find nursery-grown pots of ‘Millenium’ or ‘Blue Eddy’ (A. senescens) at area garden centers.

Nodding onion (A. cernuum) is a native, ornamental plant that blooms in summer. However, unless you see this at a native plant sale, you’ll have or order and plant seeds for this allium.

Ornamental onion is in the same family as edibles – onion, chives, shallots and garlic. My biggest concern is being careful not to pull them out, thinking they are chives escaped from the herb bed or the invasive weedy, wild garlic.

Seed library

The Glendale Branch of Indianapolis Public Library has IndyPL Seed Library, where you can check out seeds March through October.

Supported by Marion County Master Gardeners, Purdue Extension-Marion County, Fall Creek Gardens, Indy Urban Acres and others, most of the seeds are open pollinated, which means they are pollinated by wind, humans, birds or insects or other natural processes, making them genetically diverse. Many of the seeds also are heirloom.

Patrons can check out five packets per visit, or a total of 15 per season, to plant in their home gardens. You can harvest the seeds to return to the library or save them for your own garden next year.

The library also will conduct classes on sowing and saving seeds, gardening, water conservation and other topics.

Bird friendly environment as easy as a bird bath

A robin bathes in a bird bath. (C) Jarruda/canstockphoto.com

A robin bathes in a bird bath. (C) Jarruda/canstockphoto.com

All over Indianapolis, birds are nesting, laying eggs, keeping them warm, hatching babies, keeping them warm and nourished until they take flight.

That’s a lot of work, but gardeners can help lighten the avians’ parental load.

Just like we’re all worried about bees in our landscapes, some of the same practices to support them apply for bird friendly gardens. For instance, reducing or eliminating the use of insecticides means that there will be bees and other bugs in your garden. Birds eat bugs. If no bugs, no food for birds.

If you were only going to do one thing in your landscape to attract birds, a water source would be the way to go. And though we may not think about it, bees and butterflies enjoy the occasional drink, too.

Confession time. A few weeks ago, I was changing the water in a shallow, glass bowl on a wrought iron stand in the front garden. To my horror, there were about a dozen bees drowned in the bowl. To prevent this from happening again, placed a thick and flat rock in the dish. The rock protrudes above the water level to provide bees, butterflies and birds a mini-landing pad and reduce the chance the bugs will drown.

I had a similar birdbath several years ago, only the glass bowl was much deeper. Again to my horror, there was a male goldfinch drowned in the bowl. So, be mindful of the depth of the birdbath.

A lot of us provide seed for birds, too. According to a 2014 Wild Bird Feeding Industry Research Foundation’s report, 39.4 percent, or 52.3 million U.S. households buy wild bird seed “at least sometimes.”

The average household spends $81.21 a year on wild bird seed to total $4.25 billion. U.S. households spent nearly $40 annually on feeders, or $2.06 billion, the foundation reported.

But what kind of seed should you buy? Depends on what kinds of birds you want to feed.

Finches, nuthatches, downy, hairy and red-bellied woodpeckers, wrens and chickadees are spotted regularly at my niger thistle feeder that hangs in the dogwood outside my living room window.

In the back, I have a feeder for sunflower or safflower seeds. I rotate them to discourage grackles and squirrels, which don’t like safflower seeds. Chipmunks, though, tend to eat any seed I put there. So do cardinals, mourning doves, chickadees, titmice and finches.

Place feeders where you can see them and enjoy their visitors. It’s best to put feeders in an open section of the garden where the falling seed won’t smother plants.

Lastly, create a good habitat in the landscape to provide birds shelter and protection from predators and safe places to nest and raise their young. Shade and ornamental trees, evergreens, flowering shrubs and perennials all fill that need.

Don’t get tangled up with the wrong vine

‘Blue My Mind’ evolvulus forms the base of a sun-loving container with ‘Alligator Tears’ coleus. Photo courtesy Proven Winners

‘Blue My Mind’ evolvulus forms the base of a sun-loving container with ‘Alligator Tears’ coleus. Photo courtesy Proven Winners

The basic design elements of planting a container are pretty simple: thriller, filler and spiller.

The thriller is the focal point of the pot, usually the tallest plant. Fillers are just that, they fill in gaps and help round out the planting. The spillers are the vines or other plants that trail over the side of the pot.

For decades, the main trailing plant has been variegated vinca vine (V. major). Several years, ago, the chartreuse ‘Margarite’ sweet potato vine (Ipomoea batatas) started earning high marks for its trailing habit.

‘Margarite’ can be a bit of a thug in a pot or hanging basket, frequently over whelming its plant mates. The same with the Wave brand of petunias, which with a spread of 3 feet or more, can completely consume a container. Each of these will work in really large containers, or even better, as a summer groundcover.

Besides Garnet Lace, Illusion sweet potato vines come in chartreuse and purple-bronze. Photo courtesy Proven Winners

Besides Garnet Lace, Illusion sweet potato vines come in chartreuse and purple-bronze. Photo courtesy Proven Winners

For a pot, look for other sweet potato vines, such as Illusion Emerald Lace, which is chartreus, or Midnight Lace, which is purple. Each is a good trailer that reach 2-3 feet, but without the thuggish tendencies of other sweet potato vines.

The natural habit for petunias is to trail, so about any of them will work as a spiller in a pot without consuming it. Among my favorites is Proven Winners’ ‘Royal Velvet’, the country’s best-selling petunia, which has a wonderful fragrance, an attribute frequently bred out of hybrids.

Wire vine acts as the perfect foil for blue plumbago (P. auriculata) and a tricolor sage (Salvia officinalis). Photo courtesy Proven Winners

Wire vine acts as the perfect foil for blue plumbago (P. auriculata) and a tricolor sage (Salvia officinalis). Photo courtesy Proven Winners

If you are looking for something else trial as a trailer, here are a couple of suggestions:

‘Blue My Mind’, sometimes called a dwarf morning glory (Evolvulus), is a true-blue winner. This sun-loving, heat- and humidity-tolerant annual has silvery-green leaves and blue flowers about the size of a quarter. It gets about 6 inches tall with a 12-15 inch spread.

The shade tolerant Torenia Summer Wave Blue is a great substitute for lobelia in pots and hanging baskets. Photo courtesy Proven Winners

The shade tolerant Torenia Summer Wave Blue is a great substitute for lobelia in pots and hanging baskets. Photo courtesy Proven Winners 

Creeping wire vine (Muehlenbeckia axillaris) offers a light, delicate foil to larger to containers for sunny to partly sunny locations. It gets about 4 inches tall with a spread of about 18 inches. The dark stems and green leaves provide a nice, contrasting texture to bolder plants, such as petunias and geraniums.

Torenia Yellow Moon. Photo courtesy Log House Plants

Torenia Yellow Moon. Photo courtesy Log House Plants 

‘Summer Blue Wave’ Torenia is a terrific trailer for shade to part sun, performing much better than any lobelia in a pot or hanging basket. Torenia, sometimes called wishbone flower, comes in other colors, too, including ‘Yellow Moon’, which is yellow with a grape-colored throat.

Saving the lives of warm-season plants

Hold off planting frost-tender geraniums and warm season vegetables and herbs until about May 10. (C) NDPetitt/morguefile.com

Hold off planting frost-tender geraniums and warm season vegetables and herbs until about May 10. (C) NDPetitt/morguefile.com

I’ve been saving lives the last couple of weeks…the lives of basil, peppers, tomatoes, rosemary, impatiens and geraniums (Pelargonium), to name a few.

That’s because people want to buy these plants at the garden center where I work, even though it’s too early. Call it the 70-degree temperature syndrome. Symptoms include trying to rush the season. Even though temps are warm, the soil has not reached the right temperature for the plants to grow and thrive. That’s why the rule of thumb for planting warm-season vegetables and flowers is May 10. In fact, temperature dropped to 36 degrees in central Indiana on May 13, 2013.

So, if you can’t plant them yet, why do garden centers have them for sale? Because customers want them, or think they want them. Some lucky people buy plants early to hold over in their greenhouse until they can be planted outdoors. Others say they will keep them in the garage, possible depriving plants of necessary light. Others say they plan to leave them outdoors during the day and move them indoors at night.

These are all viable options, but require some vigilance on the part of the buyer to make sure plants are watered as needed. The lack of light may cause plants to stretch and become weak.

Why not let the garden center do all the work necessary to keep the plants alive until planting time? That’s less worry on your part. And you’ll know that the plants will be well tended so they will be at their best.

Show your school colors

Getting ready for high school or college graduation celebrations in the backyard? Talk to garden centers now to make sure you can get flowers in the school colors you want. Most garden centers will help you find plants and colors you need.

Stick with annuals to carry the school-color theme. Perennials are iffy about their bloom times and getting just the right color may be challenging. Most of the time, annuals are already blooming, so you can make sure you get the colors you need.

Some colors, such as black, are going to be harder to find, even in annuals. There are a few black petunia varieties on the market, or look for black mondo grass (Ophiopogon planiscapus ‘Nigrescens’).

For gray or silver, look for licorice vine (Helichrysum petiolare) or dusty miller (Senecio cineraria).

If you have any dried or faux hydrangea flowers, you can always spray paint them any color you need and stick them in a pot with annuals or use as a bouquet for a tabletop arrangement.

Kids gardening: Good for vitamin N

Photo courtesy Bonnie Plants

Photo courtesy Bonnie Plants

We hear a lot about vitamin deficiencies, and kids are not immune, frequently coming up short on their vitamin N for nature. One way to bolster their vitamin N is to get kids involved in gardening with something other than weeding. Even I hate to weed, but I love planting and growing stuff, and picking vegetables and flowers.

Crops like strawberries and purple carrots are fun for kids (and adults) to grow. Start small. Give children their own spot or pot in an area with at least six hours of direct sun, and reasonably close to a water source.

Allow them to select what they want to grow because they are more likely to eat the veggies and fruits. Certainly a few flowers, such as marigolds, would be all right, too. Feel free to narrow the field by suggesting eight or 10 crops that kids can choose from to fit the space available. Here are a few suggestions:

Strawberries

Everbearing or day neutral strawberries bloom and produce all summer long. Although a small planting will not yield dozens of strawberries, there should be enough to satisfy an occasional summer dessert. Tristar, Tristan and Tribute are cultivars to consider. (I grow Tristan in a window box.) Buy plants.

Carrots

Sure, carrots are orange, but they can also be purple, red, yellow and pink. The more dense the color, the higher the carotene and the better for you. Carrots are fairly easy to grow, especially in well-worked loose, loamy or sandy soil. Grow in a container that is at least 12 inches deep. Botanical Interests offers Carnival Blend, Atomic Red and Cosmic Purple carrots. Burpee has Kaleidoscope Mix, Rainbow Hybrid and Purple Dragon carrots. Sow seeds.

Green beans

Purple green beans are not only delicious, they are beautiful on the plant. The purple pods against the green leaves also make the vegetable easy to spot for picking at just the right size. Don’t be alarmed, though, because the beans turn green when cooked. Sow seeds. Some to consider: Royalty Purple from Rare Seeds, Purple Podded Pole from Burpee and Dwarf Velour French from Park Seed.

Cherry tomatoes

Cherry tomatoes are about the best producing plants in the garden. For most of the summer, you can pick a handful to munch on while wandering in the garden, or for a salad. Kids, in particular seem to like the yellow pear cherry tomatoes, but there are orange, black and purple types, too, with red the most common. Buy plants.

One of the best sources for getting our children and future gardeners involved is National Gardening Association’s Kids Gardening. You’ll find tips and techniques for families, classroom-ready lessons for educators and more.