Powdery Mildew Disease Resistant Cultivars

Powdery mildew on herbaceous peony

Powdery mildew on herbaceous peony

Gardeners have learned to associate certain plants with a troublesome disease(s). Powdery and downy mildews have become epidemic in many regions of the U.S. Best ways for managing mildew diseases are prevention, good cultural practices, and spraying.. First, avoid planting susceptible cultivars. Plant in the proper location and space plants far enough apart so they’re not touching. Surrounding vegetation should not block air movement through the garden.

Follow good cultural practices such as reducing or eliminating overhead irrigation practices. Fertilize to optimize plant health, but avoid over-fertilization with nitrogen as it stimulates young, succulent growth which can be more susceptible to infection.

Some moderately susceptible cultivars may require protection with fungicide sprays, particularly if environmental conditions are highly favorable for onset of mildew diseases. Dig up and eliminate susceptible cultivars of lilac, roses, crape myrtle, impatiens, zinnias or summer phloxes. Plant breeders continue to provide gardeners with better disease resistant cultivars. In recent years, notable examples of resistant plants include:

Crape myrtles – ‘Catawba’, ‘Hopi’, ‘Cherokee’
Crabapples – ‘Prairifire’, ‘Sugar Tyme’, lots others
Dogwood (Cornus florida)– ‘Cherokee Brave’, ‘Appalachian Joy’, ‘Appalachian Snow’, ‘Appalachian Mist’

Dogwood hybrids (C. florida x C. kousa) – ‘Stellar Pink’, ‘Stardust’, ‘Galaxy’, ‘Constellation’ , ‘Aurora’
Sycamore – ‘Columbia’, ‘Liberty’, Yarwood, Exclamation™
Summer phlox – ‘David’, ‘Robert Poore’, ‘Delta Snow’, ‘Speed Limit 45’
Lilac – ‘Bloomerang’, ‘Betsy Ross’,  S. meyeri ‘Miss Kim’, S. pekinensis

Monardas (beebalm) – ‘Marshall’s Delight’, ‘Blaustrumph’, ‘Colrain Red’.

Rhododendrons – R. yakushimanum, R. macrophyllum, R. ‘Nova Zembla,’ R. ‘Palestrina’
Roses – Simplicity™ and Meidiland™ roses, Rosa rugosa varieties
Zinnias – Z. angustifolius ‘Profusion or Zahara series; Pulcino and African varieties

One final thought: if foliage infections break out on garden plants in very late summer or fall, spraying a preventative fungicide is generally not necessary or impractical. Instead, practice good garden sanitation, a thorough clean-up of infected leaves and stems. For infected annuals and perennials, gather up infected debris and discard. Do not add it to a compost pile, but throw it curbside for pickup or add to a burn pile, obtaining the proper burn permits.

Five Simple Pruning Tips For DIYers

March Rejuvenated viburnum 3 months after cutback

March Rejuvenated viburnum 3 months after cutback

Small Dramm pruner perfect for small 1/4 inch pruning cuts

Small Dramm pruner perfect for small 1/4 inch pruning cuts

Gardeners are frequently scared about making pruning mistakes. There are lots of gardening books filled with lots of before and after photos. Let’s face facts…your yard tree or shrub does look like the ones pictured in the pruning book.

Here are my simple 5 steps for pruning:

  1. Why and When to prune: You can prune a tree or shrub any day of the year. The best time is generally in late winter. Choose a comfortable weather day to work outdoors so you’re not in a hurry. Remove low growing branches in any month. Branches that are dead, broken, infested with scale insects, or diseased can also be sawed or lopped off anytime. If the job involves major pruning, e.g. 30% of branches removed, spring or summer pruning is best time.
  2. Flowering shrubs or trees — when do they bloom?  Spring flowering shrubs and trees are best pruned immediately after or within one month after flowering. Can’t wait?…then prune when you’re ready. Crabapples, ornamental cherries, redbuds, dogwoods, azaleas, lilacs, forsythias, and spireas bloom on old wood in spring. Summer flowering woody plants bloom on new wood. Examples include most (not all) hydrangeas, chaste trees (Vitex), crape myrtles, althea (Hibiscus), butterfly bush (Buddleia), and roses.
  3. Make the big cuts first. Take your time! Observe the tree from several points to determine the best cuts. Making many small cuts is okay, but they’re a lot more time consuming. Small pruning cuts heal faster than bigger ones. Completely rejuvenated shrubs are cut back 6 – 12 inches above the ground. Applying pruning wound paint is not necessary.
  4. Use sharp pruning tools — Don’t plan to do all work in 1 year. If the tree has been neglected for several years, it may take 3-4 years to bring back desired shape and health. To repeat, don’t remove more 30% of branches in any one year.
  5. Large shade trees — hire a certified arborist who should be properly insured and licensed. Maples, oaks, lindens, elms, birches, and others should be pruned every 5 years. Tree topping should be avoided as this practice results in a tree potentially more hazardous.

Types of Garden Irrigation

Irrigation system

Irrigation system

Tree irrigation

Tree irrigation

These days there are lots of choices in watering gardens, individual containers, and newly planted trees. Before setting your flowers or veggies, install drip lines or soaker hoses. These systems are the most efficient method of watering and put less hurt on your water bill.

Drip systems deliver water at ground level and do not wet the foliage, limit evaporation loss, and result in less foliar disease infections. Soaker hoses and simple drip systems are available at full-service garden centers. They save water because it doesn’t end up on sidewalks or driveways.

Drip irrigation, also called “trickle irrigation,” allows you to custom-design a watering system for flower, vegetable, small fruit beds, and containers. Water flows through flexible tubing and out of emitters. Spacing for emitters preset by the manufacturer or set by the gardener. Always inspect emitters as they may clog up or rabbits and other critters may bite into the water line. Install a filter or strainer at the faucet to catch all debris and dirt. Clean out the filters every few weeks.

Over a 12- 24 hour intervals, drip or soaker systems deliver a column of water to a depth of 12 inches or more into the soil. This is adequate for most plants from shallow rooted annuals to deep rooted trees.

Tree watering bag

Tree watering bag

What about oscillating or overhead sprinklers? They are best confined to your lawn and not your flower or vegetable garden. Sprinklers provide an even supply of water quickly, but have two drawbacks. A sprinkler usually wastes water, spilling on sidewalks and driveways. Plant foliage gets soaked, and this may result in mildew and leaf spot disease infections.

While you’re away, an automatic watering systems may be what you need. All you do is set a timer that is attached to the hose or faucet. Two types, mechanical and electrical timers, are sold. Just attach timer to a faucet and set it to turn water on and off. Electronic timers offers the added benefit of watering at different times and days of the week.

Shopping Tips When Purchasing Plants


Sale of Deer resistant Plants

Idea: Grouping Deer Resistant Plants for Sale

Wonderful Selection of sedums

Wonderful Selection of Sedums for sale


Spring and fall are excellent planting times and buying opportunities. A trips to a garden center can be very costly unless you go prepared. Here are some practical tips to make those shopping trips more enjoyable and a lot less expensive.

  1. Create your landscape plan first before buying plants. First, visit garden centers to pick up great landscaping ideas at garden centers. Next, prepare your shopping list.
  1. Avoid impulse shopping. You’re likely to see (and want) blooming plant at the nursery that are not on your shopping list. Check to determine how well the plant(s) will perform in your climate and soil. How much water and light do they need? How far apart to plant?
  2. Read the plant tag. Find the plant name, its mature height and spread, blooming period, light and water requirements. Don’t be in a hurry. If the tag does not contain all growing information, search online with your phone or tablet.
  3. Is the plant healthy? Avoid buying sickly yellow or nutrient starved plants. Pots should also be weed free.
  4. Select plants not full with flowers. A few flower buds are ok or buy a plant that hasn’t flowered yet. Some early flowering shrub such as forsythias, weigelas, azaleas, or lilacs may have already bloomed.
  5. Plant size on sale. Save lots of money purchasing a smaller plant.
  6. Purchase locally grown plants whenever possible. Plants have been acclimate to your region’s weather conditions.
  7. Plant warranty – does the garden center offer one? Save your purchase receipts.
  8. Certified nursery professionals- does the garden center employ them. These knowledgeable employees have received lengthy training taught by state university Extension and Research Specialists. Area master gardeners are also invaluable local resources on plant care.
  9. Other place to buy plants.  Specialty online nurseries may grow some native plants, ground covers, roses, dwarf conifers, etal. that you can’t buy locally. State and city arboretums and university botanical gardens, frequently offer seasonal plant sales. You may find hard-to-find plants for sale at reasonable prices.

    Fertilizer sales tip in display of hydrangeas

    Fertilizer sales tip in display of hydrangeas

Southern Gardeners Should Use The AHS Heat Zone Map

Balloon flower (Platycodon)

Balloon flower (Platycodon) rated AHS 8-1

AHS Heat Map

AHS Heat Map

The AHS Heat Zone Map isn’t new. The American Horticultural Society developed it in 1960 and updated it in 1990. It has become an important reference for knowing both the cold and heat tolerances of garden plants. Many perennials in southern U.S. gardens struggle in the extreme heat and humidity.

The heat zone map developed by AHS is based on heat, rather than cold, to determine a plant’s ability to survive in a specific location. It uses summer temperatures to demonstrate a specific plant’s ability to survive or handle the stress of high summer temperatures.

The U.S. Heat Zone Map is divided 12 zones. Each is derived from the number of “heat days” or the number of days the temperatures at 86ºF or higher. Each zone is identified by the average number of heat days it experiences in a year.

Heat zones are expressed with the highest heat zones listed first, followed by the lowest. For example, the heat zone rating for balloon flower (Platycodon) is AHS Heat Zone 8-1. This illustrates that Platycodon can tolerate and survive the summer heat in zones 1 through 8 (or 8 through 1). Sweetgum (Liquidambar styraciflua) is rated USDA hardiness 6 to 9, and AHS heat 9 to 6. A plant is listed as having AHS Heat Zone: 9-5, the growing season may be too short or summer temperatures not high enough for plants to flower in zones 1 to 4.

Several environmental factors, such as water, light, daylength, oxygen, and air circulation and pollutants, can skew the accuracy of a particular heat zone. Amount of rainfall is the most critical; plants lacking water are more susceptible to injury from heat.

Some plants vary in the ability to withstand heat, not only from species to species but even among individual plants of the same species! Unusual seasons- fewer or more hot days than normal- will invariably affect results in your garden. Sometimes, individual plant cultivars may survive outside their designated heat zone.

The AHS Heat Zone Map is intended to supplement the USDA Hardiness Zone Map, permitting gardeners to select plants based on their ability to survive seasonal temperature extremes in their region. Unfortunately, many plant labels (tags) still do not list their heat tolerance.

Are Your Plants Deficient In Magnesium?

Mg Deficient Boston Fern

Mg Deficient Boston Fern

Pink Double Knockout in nutritional stress

Pink Double Knockout with slight nutritional stress

Magnesium (Mg) is the central element involved in chlorophyll synthesis, a crucial nutrient in photosynthesis, and in maintaining vibrant green leaves. Like calcium, magnesium is required by plants in large enough quantities. It is a “macro-nutrient”, as important as nitrogen (N), phosphorus (P), and potassium (K), the latter three adsorbed by plants in greater amounts.

Magnesium plays a key role in chlorophyll synthesis, in fruit and nut production, and is critical for seed germination. Magnesium helps strengthen cell walls and improves plant uptake of nitrogen, phosphorus, and sulfur. Plants such as tomatoes, peppers, and roses need high levels of magnesium for optimal growth. However, plants often do not show symptoms of magnesium deficiency until it becomes severe.

Deficiency symptoms appear first in the youngest foliage. Magnesium deficiency shows up on most leaves as interveinal yellowing (chlorosis). Dolomitic limestone, frequently applied to adjust soil pH, will also supply some magnesium. Many water-soluble fertilizers like Miracle-Gro® and Schultz® Plant Food contain magnesium.

Magnesium deficiency causes yellowing of leaf edges on older leaves, compared with the interveinal yellowing present when iron is deficient. Magnesium deficiency can result in complete defoliation. In certain plants, such as geraniums, magnesium deficiency also causes the leaves to curl slightly upward.

Magnesium sulfate (i.e. Epsom salts) is an inexpensive source of water-soluble magnesium. It may also be applied as a foliar spray and is taken up quickly. It is available in drug and grocery stores and is compatible with other water-soluble fertilizers. Generally, 1 oz. per 100 gal. of Epsom salts supplies about 7.5 ppm of magnesium.

Many home gardeners are sold on applying Epsom salts to peppers, tomatoes, roses and some foliage house plants like ferns and dwarf palms. Citrus crops in sandy Florida soils and house plant citrus also respond by darker greening of leaves.

Little Goblin® Series Of Deciduous Hollies

Ilex-verticillata 'Little Goblin' (photo by Tim Wood, Spring Meadow Nursery, Grand Haven, MI)

Ilex-verticillata ‘Little Goblin Red’ (photo by Tim Wood, Spring Meadow Nursery, Grand Haven, MI)

'Little Goblin Orange' (NV )

‘Little Goblin Orange’ (NCIV2)

Little Goblin® Red (Ilex verticillata ‘NCIV1’) is one of the new creation from plant breeder Dr. Tom Ranney, at the North Carolina Research And Extension Center in Mills River, NC. It is the first ever tetraploid winterberry. This dwarf variety is also exceptionally hardy and easy to care for.

Little Goblin® Orange (‘NCIV2’) is extremely early flowering and early fruiting winterberry holly produces abundant bright orange berries on a 3-4 feet tall and wide plant. This compact variety is ideal for residential landscapes. It makes an excellent specimen, mass planting, or row beside a driveway or walking path. The berry-laden branches also make beautiful cuts for arrangements!

It thrives in a wide variety of conditions, including almost any soil type, preferably acidic, and climate. It loves moist (even wet) soil, and stands up to hot summers and cold winters with equal resilience (USDA hardiness zones 3 to 9). Plant in a sunny open location for best viewing. This holly series is moderately shaden tolerant, although flower and fruit numbers may be lower. Hollies established after one year are very drought tolerant.

This first ever tetraploid winterberry brings you extra big and abundant rich-red (or orange) berries on a dwarf plant. You will treasure this plant for gardens, mass plantings or as a cut branch. Its compact size makes it ideal for residential landscapes. Prune annually at start of spring to maintain desired height and plant symmetry. Feed plant(s) at planting and in late winter with granular 10-10-10 or an equivalent fertilizer.  NOTE: for the best fruiting, set a male pollinator (like Mr. Poppins™) nearby.

Little Goblin holly series is uniquely prolific, with a smaller form that is positively bursting with berries, the red or orange fruits overshadowing the leaves and creating a welcoming sight for most songbirds over a cold winter.

Landscape Trees With Winter Interest

Paper bark maple

Paper bark maple

Jacquemonti birch

Jacquemonti birch

Does your winter landscape look a bit shabby? This coming spring take some action by planting trees that should perk up its appearance. New tree choices should ratchet up seasonal interest, attract more bees, butterflies, and hummingbirds in the spring-summer and hungry fruit feeding birds in fall-winter.

Making smart tree choices can add four-seasons of interest to your yard. In making your shopping choices, look for such arbor features as branch architecture, bark color(s), foliage texture, flowering, and resulting seeds and fruits.

Some of my favorites of trees with winter season appeal are:

Dogwoods: flowering dogwood (Cornus florida), Chinese dogwood (C. kousa) and Japanese cornel (C. officinalis). All three offer winter or spring flowering, unique horizontal branching, fruiting, and autumn leaf color. Latter two species show off exfoliating bark in winter.

Japanese maple (Acer palmatum): including coral bark variety ‘Sango Kaku’ and yellow bark of ‘Bihou’.

Paper bark maple (Acer griseum): stunning cherry red exfoliating bark.

Trifoliate maple (Acer truncatum): nice exfoliating tan colored bark.

Birches: River birch (Betula nigra Heritage® or Dura Heat ®), Himalayan birch (B. jacquemontii), and paper birch (B. papyrifera) – all with brightly colored exfoliating bark (latter two birch species for northern areas within USDA hardiness zones 2-6).

Crabapple (Malus spp.): this spring blooming tree (hundreds of varieties), many bearing colorful fruits that invite birds to your property.

Ornamental Flowering Cherry (Prunus spp.): some varieties exhibit stunning ruby red bark color.

Hollies (Ilex spp.): female forms produce full crops of with bright red fruits. Yellow berried forms are also available.

Green Hawthorn (Crataegus viridis ‘Winter King’): bright red fruits cover branches during the winter.


Japanese Stewartia (Stewartia pseudocamellia): patchy exfoliating creamy colored inner bark.

Persian Ironwood (Parrotia persica): patchy exfoliating bark exposing a light colored inner wood.

Ginkgo (Ginkgo biloba): this ancient deciduous large landscape tree with brightly colored triangular fall foliage and grayish-brown furrowed bark.

Crape myrtles (Lagerstroemia spp.): choice of many cultivars; strong muscular bark that exfoliates to reveal colorful inner wood.

Arctic Fire™ Dogwood Brightens Up Winter Landscape

Intense Red Bark cut for floral arrangements

Intense Red Bark cuts for use in floral arrangements

'Arctic Fire dogwood at Univ. of Tennessee Gardens in Knoxville

‘Arctic Fire dogwood at Univ. of Tennessee Gardens in Knoxville

Red-twig or red osier dogwood (Cornus stolonifera) is a native shrub (USDA hardiness zones 2-7). It reaches 8 to 10 feet in height and roots sucker prolifically. It can become a chore keeping it contained in small garden spaces.

Arctic Fire™ is a superior cultivar identified by its fiery red stems and compact growth habit. Expect some minor suckering, but this cultivar is far less invasive than the species.

Arctic Fire grows 4-5 feet tall and wide. That’s almost less than half the height of other red osier shrub dogwoods.  Its stunning red branches are impossible to ignore! The crimson branches are particularly striking on a frosty or snow morning.

In spring flat headed creamy white flowers appear. Arctic Fire dogwood has dark green foliage through the growing season. The pointy foliage turns purple-tinged red in autumn. In mid- to late-summer clusters of creamy white flowers form on branch tips. White berries form in late summer and attract hungry birds.

Arctic Fire grows in average well-drained soil and in partial to full-day sunlight. It is an amazingly adaptable plant. Once established it will tolerate extremely dry soil and stand up to occasional standing water. It is highly tolerant of urban air pollution.

Best stem color appears on new growth. Prune back old stems hard immediately after spring flowering  to ensure an intense red twig bark display the following winter. Old branch wood that is three years and older should be removed at or near ground level. In early spring apply a slow release fertilizer such as Osmocote™ or Nutrikote™ specialized for trees and shrubs. Follow the label rate of application. Deer usually stay away from red osier dogwoods.

Utilize it as a perennial or shrub borders. Winter branches and spring flowers may be cut for flower arrangements.

Saving Heirloom Seeds

Dogwood fruits (called cornels)

Dogwood fruits (called cornels)

Seed heads of Goldenrod (Solidago)

Seed heads of Goldenrod (Solidago)

At the end of each growing season, you may choose to collect seeds from favorite flowering annuals and vegetables to holdover and plant in next year’s garden. Some may be heirloom varieties that you have saved for many years because you like their productivity or flavor.

Note: these seeds should not be “hybrids”. Hybrids represent a cross between two specific parent plants resulting in such as hybrid Big Boy™ tomato, Spirit™ Hybrid pumpkin, or hybrid Wave™ petunias. Saved seeds of hybrid vegetables and flowers rarely come back “true.” Progeny won’t yield back the exact flowers, fruits, or yields in the next crop. Their resistance to diseases may also be lost.

In late fall nursery producers collect dogwood, maple, and other seeds from landscape trees or shrubs. They will clean and sow seeds in a prepared planting bed. Dormant seeds will be chilled (called “vernalization”) in the ground over winter and germinate next spring. Eventually, seedlings may become new woody plants or serve as rootstock upon which specific cultivars (varieties) of dogwood or maple are grafted or budded onto.

If you are saving wildflower seeds to re-establish a meadow next spring, harvest them in fall. Seeds may be chilled in a refrigerator (for spring planting) or sow directly into a newly prepared garden bed in the fall.

To save non-hybrid seeds:
• Start by inspecting seed heads a few weeks prior to the seeds shattering. Seedheads should appear dry. Pulpy seeds (fruits) will have colored up and are starting to shrivel. Be watchful that seeds don’t blow away. If you delay a day or two too long, they may be gone.
• Big seeds are easier to save than tiny seeds. Indoors, spread the seeds out over sheets of newspaper, paper towel, or a screen mesh.
• Separate the seeds from any chaff. Small seeds may dry in 7 to 10 days. Larger seeds may take two weeks or longer.
• Store seeds in a zipper-type plastic freezer bag or in a glass jar with a screw-on lid. Baby-food and Mason jars are also excellent for seed storage. Close the lids securely. Label containers with cultivar name of each plant (flower) and record collection date of all seeds to be stored. Place the containers in either a refrigerator or freezer. You may also store them in an unheated garage, but wildly fluctuating temperatures could damage seeds.