Garden Talk: September 6, 2012

From NGA Editors

Song Bird Kale

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Ornamental kale is one of the best plants for adding long-lasting and easy-care color to the fall garden. These sturdy plants keep their good looks long after frost has finished off many autumn flowers. The bright colors and interesting textures of their foliage are as ornamental as any blossom -- and much more durable.

New for 2012 is the compact Song Bird™ series, bred by American Takii, Inc. Once temperatures begin to fall into the 55-60 degree F range, Songbird™ kale begins to color, forming ruffled rosettes of leaves in shades of pink, rose, and white that look like large, exotic flowers held in a ruff of green. Plants grow 8-12 inches tall and 12-14 inches wide and do best in full sun. Hybrid Song Bird has a uniform, upright growth habit that allows rainwater to drain out of the rosette, keeping plants looking good no matter the weather.

Ornamental kale looks great when mixed with other seasonal plants like mums and pansies or added to beds of ornamental grasses, asters, and other fall-blooming perennials. Plants set out in later summer and fall are usually less troubled by cabbage family pests such as cabbage loopers, but if these pests do arrive, they can be controlled with the safe natural pesticide Bacillus thuringiensis (Bt). You can grow your own plants from seed or purchase started plants at your local garden store. Sow seeds in midsummer, about 10 weeks before your fall frost date, in order to have good sized plants when autumn arrives.

To find out more about Song Bird™ ornamental kale, go to: National Garden Bureau.

Downy Mildew of Impatiens

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One of the standbys of the shade garden, impatiens has in the past been a pretty trouble-free plant in most situations. Unfortunately, a new disease has arrived on the scene that threatens impatiens in many parts of the country. Although downy mildew of impatiens was first observed in the U.S. in 2004, it reached epidemic proportions by last year.

Caused by the water mold Plasmopara obducens, the first signs of the disease are stunted, yellowing plants, with leaves that may curl downward as if they were suffering from drought. The undersides of the leaves may be covered with a fluffy white coating. Eventually the leaves and flowers drop, leaving bare stems with only a few small, yellow leaves left clinging to them. If you are unsure of your diagnosis, contact your local Extension Service for assistance.

Cool temperatures, especially at night, wet foliage, and high humidity all favor the development of this destructive disease. It infects all types of garden impatiens (Impatiens walleriana), as well as balsam impatiens (I. balsamina). However, New Guinea impatiens (I. hawkeri), including SunPatiens®, are not affected.

Infected plants will not recover, so if any develop symptoms, pull them up, bag them in plastic, and put them in the trash, not in your compost pile. Because the disease can persist in the soil for years, if you have infected impatiens in a bed, it's a good idea to choose different plants that are not susceptible to this disease for that bed the next season, such as New Guinea impatiens, coleus, or begonias.

For more information on downy mildew of impatiens in home gardens, including color pictures of symptoms, go to: UMass Extension.

Hardy Geraniums for Fall Color

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When it comes to fall foliage colors, we usually think first of trees and shrubs. From the flaming reds, yellows, and oranges of maples to the rich red of chokeberry and the bright yellow of the ginkgo tree, many woody plants put on an eye-catching seasonal show as the weather cools.

But for some excellent fall leaf color on the floor of the garden, as well as attractive flowers earlier in the season, along with easy care, consider some of the hardy geraniums. Also known as cranesbills for the shape of their seedpods, these Geranium species are not related to the bright Pelargoniums that, confusingly, are commonly called geraniums.

From among the many choices of hardy geraniums available, a multi-year evaluation of a wide range species and cultivars carried out at the Chicago Botanic Garden, located in zone 5b, can help you choose the best for continued seasonal interest. Over 100 Geranium species and cultivars were assessed for their ornamental traits, resistance to pests and disease, cultural adaptability, and winter hardiness, and given a rating of one to four stars.

Among the hardy geraniums that received a rating of three or four stars, many display colorful leaves in autumn. 'Brookside', with deep blue flowers in late spring to midsummer, takes on hues of red and burgundy. The prolifically blooming Rozanne (G.'Gerwat') is covered with purple-blue blossoms all summer long, and its leaves make a tapestry of red, orange, and yellow in fall. The bigroot geranium cultivars 'Lohfelden' and 'Minor' were top-rated, but all varieties of this species are good choices for late season leaf color. Purple flowering G. wlassovianum (pictured) and pink or white flowered G. x cantabrigiense and its cultivars are also tops for fall color, turning shades of red and purple.

To see the ratings of all hardy geraniums evaluated, go to: Fine Gardening. To read more about hardy geraniums go to: Chicago Botanic Garden.

Safe Tomato Canning

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As summer winds down, many gardeners are saving the bounty of their vegetable gardens by canning tomatoes. And many of them are using the water bath canning method to process their jars. Water bath canning is only safe for ″high acid″ foods, which have sufficient acidity to prevent the growth of bacteria that produce deadly toxins. Folks used to assume that tomatoes were naturally high enough in acid to make water bath processing a safe method for canning tomatoes. But it turns out this isn't so.

According to the University of Minnesota August 2012 Home Food Preservation Newsletter, recent research has shown that a number of factors, from the variety of the tomato to the soil and weather conditions it was grown in to the stage of ripeness when harvested can all affect the acidity level of tomatoes. ″Tomatoes are not consistently 'high' in acid and today's canning recommendations require that acid be added to ALL canned tomato products even if they are pressure canned.″ the newsletter notes. It also points out that this recommendation applies equally to heirloom tomato varieties, as some of these old-time varieties are lower in acid than modern hybrids.

For safe canning, the newsletter recommends adding citric acid to tomatoes at one-half tsp per quart or one-quarter tsp per pint, or bottled lemon juice at 2 TBSP per quart or 1 TBSP per pint. Don't use fresh-squeezed lemon juice as its acid levels can vary. Vinegar (5% acidity) can be used at 4 TBSP per quart or 2 TBSP per pint, but will cause a noticeable change in flavor.

To read current and past Home Food Preservation Newsletter issues and to subscribe to this informative, free, online newsletter, go to: UMN Extension Food Safety.

 
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