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PLEASE NOTE: In the autumn of 1995, we hatched the idea for a free, local gardening publication. The following spring, we published the first issue of Michigan Gardener magazine. Advertisers, readers, and distribution sites embraced our vision. Thus began an exciting journey of helping our local gardening community grow and prosper.
After 27 years, nearly 200 issues published, and millions of copies printed, we have decided it is time to end the publication of our Print Magazine and E-Newsletter.

Ask MG: Moving houseplants outdoors

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Since many houseplants enjoy being outdoors for the summer, I brought a Norfolk Island pine outside to a sunny spot and watered it consistently. A couple weeks later, the branches and needles were almost completely browned. Was this because of too much sun or doesn’t this plant like being outdoors?

Bringing your houseplants outside for the summer can be very good for them but the correct sunlight is important. Understand that full sun indoors is about the same light conditions as shade outside. It is wise to keep your houseplants in a shady area for the summer so the foliage will be lush and the acclimation back indoors at summers’ end will be much easier.

Plant Focus: Northern sea oats

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www.monrovia.com
Bronzy fall color of northern sea oats.by George Papadelis

Ornamental grasses are one group of plants that draws a great deal of attention each fall when most of them produce their inflorescence. Consequently, gardeners re-evaluate the possibility of adding a grass or two to the landscape and more are planted in fall than any other time of year.

Ornamental grasses are an enormous group of plants that are usually perennial and typically provide attractive foliage in summer as well as winter. The four popular genera for sun are maiden grass (Miscanthus), switch grass (Panicum), fountain grass (Pennisetum), and feather reed grass (Calamagrostis). Some, like Carex (technically a sedge, not a grass) and forest grass (Hakonechloa), will tolerate shade. Northern sea oats produces beautiful seedpods and boasts tolerance of both full sun and part shade.

Eric Hofley / Michigan Gardener
The “flowers” are just emerging in this early July photograph.Park Seed
Tan winter color.Northern sea oats (Chasmanthium) is native to south, central, and eastern North America and is very hardy (zone 4). Like many other ornamental grasses, the dead foliage from the previous season should be trimmed in April to just a few inches above the ground. Spring weather will encourage the growth of bright green, grass-like leaves that are about an inch wide and 7 to 8 inches long. They develop on bamboo-like stems that typically grow from 2 to 4 feet tall. Northern sea oats’ crown is comprised of slow-spreading rhizomes that will only increase the plant’s size by a few inches per year. Plants that are well-established can be divided in spring.

Flat, green “flowers” develop on the arching stem tips from July through September. In fall, these become tan well before the foliage turns to copper in early winter. The flower heads are beautiful and the slightest breeze will send them dancing on the delicate stems from which they gracefully cascade. Snow and ice will add to their magnificence while they gradually shatter until spring.

The flowers do produce viable seed that can produce seedlings in spring. These are usually most prevalent when the soil is well-cultivated and kept quite wet. These volunteers are rarely a nuisance, but I do know of at least one gardener that has banned northern sea oats from her plant list. On the other hand, the northern sea oats in my garden has rarely produced seedlings.

Eric Hofley / Michigan Gardener
Sea green flowers shimmer in the breeze.www.monrovia.com
The summer to fall color change.Northern sea oats will thrive in full sun but will also tolerate almost total shade. In full sun, plants will grow slightly shorter and should not be allowed to dry out. Plants grown in shade or part shade are drought-tolerant once established. Try planting northern sea oats under larger trees where competition from tree roots may present a problem for other perennials.

The versatility of this plant makes it a welcome addition to almost any border planting. The bright green, narrow leaves are an excellent foil to contrast with broader foliage such as hostas, rodgersias, or perennial forget-me-nots (Brunnera). They may also be positioned near the finer foliage of astilbes or ferns. Almost any flower would be complimented by a backdrop of northern sea oats foliage. Each winter, when other perennials die back to the soil, northern sea oats stays up to provide the winter interest for which ornamental grasses are best known.

Great foliage, fascinating flowers, and almost a full year of interest make northern sea oats worth considering in your landscape. Best of all, its tolerance of sun or shade makes it suitable for use almost anywhere.

George Papadelis is the owner of Telly’s Greenhouse in Troy, MI.


At a glance: Northern sea oats

Botanical name: Chasmanthium latifolium (chaz-MAN-thee-um la-ti-FOH-lee-um)

Plant type: Perennial

Plant size: 24-48 inches tall and wide

Habit: Upright and clumping

Hardiness: Zone 4

Flower color: Sea green, maturing to bronze, then tan

Bloom period: July to September

Leaf color: Bright green, maturing to coppery gold

Leaf size: 1 inch wide, 7-8 inches long

Light: Sun to shade

Soil: Adapts to a wide range from moist to dry

Uses: Excellent backdrop for other plants and their flowers. Great 4-season interest: crisp green in the spring, dangling flowers in the summer, bronzy flower and foliage color in the fall, and tan tones in the winter.

Companion plants: Bold foliage like hostas, rodgersias, and perennial forget-me-nots (Brunnera). Fine foliage like astilbes and ferns. 

Remarks: Dangling, oat-like “flowers” shimmer in the slightest breeze. Very versatile, since it can adapt to both sun and shade, and moist to dry soils.

Ornamental grasses for shade

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Are there any ornamental grasses that will grow in partial (dappled) shade?

Most grass varieties prefer to grow in the sun, however you’ll find several that will prosper under partially shaded conditions. Remember that the plants might lose a bit of height, leaf color and flowering due to the shade, but these varieties will certainly grace your garden with their wonderful textures and motion:

• Sedge, Blue (Carex)
• Sedge, Golden (Carex)
• Northern Sea Oats (Chasmanthium)
• Hakonechloa
• Japanese Blood Grass (Imperata)

Selecting plants for stone walkway

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I have a paving stone walkway in full sun. Currently, there is gravel between the stones and I want to replace it with plants. Which ones would creep along a little, but not too much, be very low, and be able to take a little foot traffic? Also, any planting tips?

When searching for the perfect groundcover that does well in full sun, is low-growing and can stand some foot traffic, our choices are, unfortunately, extremely limited. Many sun groundcovers are low-growing, like certain varieties of Sedum or Ajuga, but they are not tolerant of foot traffic. Then, there is lilyturf (Liriope spicata). It does well in sun or shade and is content with being trampled on, but it grows to 12 inches — too tall to plant between stepping stones.
The happy medium? Thyme! This wonderful, perennial herb loves full sun, is low-growing and can take a moderate amount of foot traffic. In addition, as an added bonus, thyme emits its well-known, delicious fragrance and stepping on the plant only stirs up more of the luscious scent.

Any of the thyme varieties will perform wonderfully for this situation, creeping along slowly but surely. Lemon thyme, red thyme, woolly thyme and many more varieties offer a diverse range of foliage colors and textures, not to mention interesting variations of aromas. Don’t forget to pick a few stems for your homemade spaghetti sauce too!

When planting thyme, choose a well-drained, full-sun location. Believe it or not, thyme does its best in poor soil. Very little maintenance is necessary to be successful with it. Try not to wet the leaves when watering as this deadens their wonderful fragrance and be sure to mulch in the winter to protect the plant from heavy frosts.

Understanding stressed trees: Insects, disease, & environment

  •   2 Comments

by Steve Turner

Being an arborist is a lot like being a good detective. You get a call saying there is a problem with a tree. You ask the client questions to gather facts about the tree’s history. Then you go to the site and look for clues to the problem and ask more questions if needed. Sometimes the situation is obvious and other times it can be a real challenge, but most tree problems will fall into three categories: insect, disease, or environment. In many cases, it is a combination.

As you have heard many times before, healthy plants are more resistant to insects and disease, but what about environmental stresses? Even the healthiest plant can’t guard against weed whackers or backhoes trenching through its root system. Nine times out of ten, it is an environmental stress that leads to the insect or disease attacking the plant. This is what confuses many homeowners. For example, they see leaf scorch and want to spray it to solve the problem. However, the leaf scorch can merely be a symptom, not the main problem. Both the weed trimmer and backhoe stress examples above could cause leaf scorch or leaves to drop, but they are two very different problems that spraying would have no effect on.

You must find signs to diagnose a problem and treat it correctly; symptoms only let us know that there is a problem. A chewed leaf is a symptom unless the feeding pattern is unique to a certain type of insect; then it is a sign. A birch tree dying at the top is a symptom, but the D-shaped exit hole on the trunk is a sign that borers are present.

Now you can begin to understand how many times diseases and insects are only the symptoms of the environmental stresses that are the real problem. Too often only the symptoms are treated, without addressing the real issues that are causing the problem. A good example is leaf miner on birch trees. If you keep the tree well-watered, mulch around the root zone, avoid planting it on a berm or top of a hill, and fertilize it once a year, it will stay healthy for a long time. On the other hand, plant it in the wrong place, don’t water, mulch, or fertilize it, and you will spend quite a bit of money each spring spraying to keep it healthy.

Unfortunately, what happens too often is that the obvious problem gets treated without the root cause being addressed, which can lead to unnecessary expense and use of pesticides. Environmental stresses are very common, but can be difficult to identify. They include drought stress, improper pH of soil, girdling roots, salt build-up in the soil, lightning strikes, herbicide damage, root confinement, bad drainage, compacted soils, improper planting, change of grade, root disturbance, and many more. Some can be corrected and some cannot. It helps to know what you’re up against before you decide a course of action and whether to treat just the symptoms or try to fix the real cause.

Treatments for stressed plants

The good news is that today we have more options than ever in treating stressed plants. Not too long ago, tree care consisted of spraying everything three times a year, whether it needed it or not, and fertilizing in the fall. This hit or miss approach has become outdated and even irresponsible. As the public awareness of pesticides has grown, so has the demand for safer and more environmentally sound treatments. In recent years, science has developed more biological controls than ever before. Products such as Bt, which controls caterpillars by infecting them with a virus, are becoming the preferred choice as opposed to broad-spectrum insecticides that kill both good and bad insects.

Recently a nematode was introduced that will attack grubs and termites in the soil without affecting earthworms and other beneficial insects. They will live in the soil for years with only a single application and eliminate the need for multiple applications of pesticides on lawns, reducing the risks to both children and animals. Another product is a fungus that is antagonistic to the Dutch elm disease fungus. It has shown much promise and could mean the return of the beautiful elms that once lined so many of our streets.

Mycorrhiza use has grown by leaps and bounds in recent years as arborists have discovered the many benefits they provide to our urban trees. This beneficial fungus attaches itself to the roots of plants and creates a second root system that is much more efficient at absorbing water and nutrients for the plant. It also guards against harmful soilborne pathogens that otherwise could attack the plant. It will also increase drought and salt tolerances, increase fruiting and flowering in many plants, and reduce transplant shock. Mycorrhizae have been around for millions of years working in a symbiotic relationship with plants in forests and meadows, but in our urban landscape they have been reduced by many common cultural practices. By reintroducing them to our urban trees, we help reestablish this natural, beneficial relationship.

Steve Turner, Certified Arborist, is from Arboricultural Services in Fenton, MI.

Plant Focus: Globe amaranth (Gomphrena)

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Jonathon Hofley / Michigan Gardener
‘QIS Lilac’by George Papadelis

The dog days of summer can certainly take a toll on the garden. Many plants are well-suited for intense heat while others struggle to maintain a flower for more than a few hours. One of the most heat-tolerant, and underused, annuals is Gomphrena. Its common name is globe amaranth and it is native to Central America. Once established in the garden, globe amaranth will tolerate temperatures in the hundreds about as well as any annual. It comes in several colors and plant height can vary from just 9 inches tall to over two feet. In my opinion, the best thing about globe amaranth is that it is relatively uncommon; plants will usually draw enough attention to conjure the occasional, “What is that?” I love hearing those words of wonderment from gardeners.

Gomphrena develops clover-like, round flower spikes that are almost 1 inch across. They make a great cut flower, and when dried, they will retain their shape and color indefinitely. They will thrive in any sunny position and will tolerate a broad range of soil as long as it is well-drained. Rain can make some annuals, like petunias, droop and flop. Gomphrena, however, stands strong and erect despite high winds or rain.

Sakata Seed America
‘Gnome White’The most popular series of gomphrena is the Gnome series. It is a dwarf variety that comes in about four colors including purple, pink, and white. It only grows about 9 inches tall and wide, and makes a great edging plant. In the annual border, this is a more interesting alternative to the common marigold or ageratum. It can also be a valuable addition to containers—especially those exposed to intense sun. Its compact size makes it suitable for sale in small packs just like other, more common bedding plants. It is also one of the more inexpensive annuals you can buy.

The taller gomphrenas are the ones that I find most interesting. They can be used as a unique addition to the perennial border since they are unfamiliar to many gardeners. One of my most pleasant memories of gomphrena came to me at Longwood Gardens. The variety ‘Bicolor Rose’ was planted in a vibrant mass along with several other unique annuals. It stands about two feet tall and the rose-colored flowers sport a spot of white at the tip. This is by far one of the most vividly-colored gomphrenas available. Try this variety in small groups in the perennial garden.

Julia Hofley
‘Strawberry Fields’Sakata Seed America
‘Gnome Pink’Other tall varieties include ‘Strawberry Fields,’ with strawberry-red flowers on strong upright stems to about 24 inches. ‘Lavender Lady’ has lavender flowers on 24-inch stems. Both of these varieties are getting harder and harder to find. The ‘Woodcreek’ series (also known as the QIS series) grows 24 to 30 inches tall and comes in seven colors including lavender, pink, orange, red, purple, rose, and white. Seeds for these are somewhat more available, especially amongst the cut and dried flower circles. Plants are sometimes sold in larger packs or small pots.

Whether you garden with perennials or annuals, gomphrena provides an interesting, easy to grow, heat-tolerant choice. Gardeners often overlook gomphrena in early spring when garden center plants can appear somewhat unimpressive. But once summer comes along, few annuals can provide such a unique flower and exceptional weather tolerance.

George Papadelis is the owner of Telly’s Greenhouse in Troy, MI.


At a glance: Globe amaranth

Botanical name: Gomphrena (gom-FREE-nuh)

Plant type: Annual

Plant size: 9 to 24 inches tall and wide

Habit: Upright clump

Flower color: Lavender, rose, red, pink, orange, purple, white

Flower size: 1 inch across

Bloom period: Summer

Light: Sun

Soil: Well-drained

Uses: Shorter varieties can be used as edging plants. Taller varieties can be used both in mass annual plantings or in perennial borders.

Remarks: Exceptional heat tolerance. Stands up to wind and rain also. Excellent cut flower; when dried, retains shape and color indefinitely.

Planting a yucca in an outdoor container

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I want to plant a yucca in a container that will stay outdoors all winter. Can I use regular container potting soil? If not, what type should I use?

Container gardening for perennials and small ornamental shrubs is growing in popularity, but not without problems. The greatest challenge is overwintering. In winter, the temperature of the soil in the ground stays much warmer than the temperature of the air. In some cases, up to 40 degrees different. The problem with container gardening is that the roots of the plant are elevated above the warm earth, and the cold air quickly drops the temperature of the soil in the container below what happens naturally in the ground. This usually kills the roots of the plant and leads to a disappointing spring.

Yucca has been designated as a zone 4 plant, or able to withstand a low temperature of -20 to -30 degrees Fahrenheit if planted in the ground. If planted in an above ground container, the roots will most likely die if the soil temperature drops below 10 degrees Fahrenheit. To be successful, controlling the temperature of the root zone is the key. Even if plants are in the ground, soil temperature is still important. That is why so many gardeners swear by a good overwintering mulch. The mulch helps insulate the ground from extreme temperature changes, especially those cold January nights.

Regular container potting soil would be recommended. Be sure to fertilize as needed.

Why have my Hydrangeas changed bloom colors?

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I have a hydrangea that used to have big, blue flowers. While the flowers are still healthy, they are now a dusty pink. Is the plant sick? What happened? Can I get the blue blooms back?

No, your plant is not sick. Your hydrangeas simply need a pH and nutrient adjustment. While the flower color of white-flowering hydrangeas is unaffected by soil pH, that certainly is not true with pink and blue-flowering varieties. In the case of the latter, the flower color is largely determined by the soil pH. In general, hydrangeas planted in more alkaline soils will be pink. The more acidic the soil, the bluer the flowers become. In between, they tend to take on a somewhat “muddy” appearance.

The clearest blues require the minor nutrient aluminum to develop fully. Since phosphorous tends to tie up available aluminum in the soil, one should avoid high phosphorous fertilizers if the bluer flower color is desired. The addition of aluminum sulfate is perhaps the single best way to promote bluer flowers. Use one pound (2 cups) per three feet of height around each shrub in the spring and water thoroughly.

Insect control for Lonicera vine

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I have a Lonicera ‘Dropmore Scarlet’ vine that gets about 4 hours of sun a day. I noticed that the top of the plant was covered with masses of tiny, white insects. Starting at the bottom of the plant, the leaves had all browned and fallen off. What is the insect and what should I do?

The insects on the new growth and the brown leaves at the bottom may not be related cause and effects. The insects you are observing on the new growth are no doubt aphids. Aphids love honeysuckle and are often found on the new growth causing malformed, rolled up foliage and twisted stem growth. Since they tend to cluster on the tips (and have distorted the new growth anyway), trimming them off is often an effective control strategy. Introducing lady bugs as a natural predator also works. Chemically, a systemic insecticide such as Orthene does a good job, even though the rolled up leaves may protect them from direct spraying.

The brown leaves at the bottom are due to something else. It could be due to insufficient sunlight (honeysuckles do best in full sun) or lack of fertilizer (a balanced 10-10-10 will normally do the trick). If you noticed the leaves with a dusty, white coating before they turned brown, the cause may have been powdery mildew. Honeysuckles, particularly those in shaded locations, are quite susceptible. “Remedy,” a new fungicide from Bonide is quite effective in the control of mildew. It is safer to use and not as harmful to the environment as many of the other fungicides.

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