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My hydrangeas are over seven years old and they have always been healthy and blooming until this year. One lacecap hydrangea was developing leaves, but they were small and curled. The stalks from this past year on the other hydrangeas were not developing any leaves even though they had buds on them when I checked a few weeks prior to this. It appears something is boring a hole into the center of the stalks and leaving “sawdust” on the new leaves. All the hydrangeas have this same problem. On the lacecap, I cut away more and more, until I reached the base of the plant and thus had to destroy the plant altogether. The bugs look like ants with wings. They are not termites, as their bodies have a shape to them. I know that the plants will not bloom this year and I don’t know if they will live. This appears to have happened in less than three weeks. Any ideas?

Although hydrangeas can be susceptible to leaf spots, blights, wilts and powdery mildew, it is rare that insects plague them. The hollow stems you are finding may be the natural growth of your hydrangeas. Some have hollow stems, while some have hollow stems filled with white to brown pith, depending on the age of the particular stem. The presence of pests may actually be a sign of another problem that is causing your plants stress. Insects that may trouble the hydrangea include aphids, leaf tiers, rose chafers, oystershell scale and four-lined plant bugs.

Aphids distort the new growth and coat the leaves with sticky honeydew. These insects can be dislodged with a high-pressure water spray from your garden hose.

A leaf tier is evidenced by webs on the leaves and over the tips of the branches. Pick these insects off by hand.

Rose chafers are light tan beetles with red, spindly legs. They occur in large numbers where the soils are sandy. Chemicals are ineffective because more rose chafers quickly move into the treated area to replace those killed by pesticides.

Oystershell scale infests the upper stems of the hydrangea and often goes unnoticed. Sprays of dormant oil should control the overwintering stages and are less harmful to beneficial predators that help to control scale. 

Four-lined plant bug causes round, brown, sunken spots on the leaves. The injury is often thought to be disease. Sprays are rarely needed for this.

Your local garden center will have pesticide sprays that you can use to control the crawlers. Ask their experts to help you choose the right product and, as always, read the labels carefully before using. Your keen observations and quick actions are the key to healthy plants.

I have an oak and a birch in my yard of many trees. Every late May or early June, the new leaves start to dry around the edges and some drop, looking somewhat fall-like. Both trees appear healthy until this happens almost overnight. What could this be?

Leaf scorch, sometimes called marginal leaf burn, describes the death of tissue along the edge of the leaf. This symptom develops when sufficient water does not reach the leaf margin cells. Causes include: 1) insufficient moisture in the soil; 2) water is lost too quickly from the leaves to be replaced adequately; 3) roots have been killed by plant pathogens, excavation, or compaction; 4) girdling; 5) injury; or 6) fungi or bacteria invade and plug the water-conducting vessels (xylem) in the plant. Here is a brief discussion of a few of these causes:

Make sure your trees get enough water. If your soil is very sandy (drains quickly), you might need to water more often. Or they might be in a very poorly draining site (heavy clay) and are waterlogged, of which the symptoms are the same as too little water.

Young leaves in the spring are often very tender and subject to damage from strong winds. Warm days following cool nights, when combined with frequent spring winds, can cause rapid desiccation of the leaves. The leaf margin is the most likely injured part of the leaf. This desiccation can occur even if the soil has adequate moisture, because the wind can draw water from the leaves faster than the tree can move it from the soil into the leaves. Very young trees may not exhibit symptoms because they are smaller, closer to the ground, and more protected from the wind, and also because they have less distance to move water through the plant to resupply the leaves. Newly transplanted trees, with limited root systems, and those which have just begun rapid growth after a couple of years of establishment following transplanting may be the most likely to show the symptoms. However, under the right conditions, this spring wind desiccation injury can occur in larger trees as well.

One of the most common and yet least recognized causes of tree problems is root disturbance, often associated with some sort of construction activity. Excavation, even at a distance of 10 feet from the trunk of a large tree, may destroy 30 percent of the root system. It does not take major soil disturbance to cause damage. Cutting a narrow ditch for laying utility cable effectively disconnects the entire root system on that side of the tree. Changes in grade will also damage tree root systems by upsetting the balance of air and water the roots need to survive. Soil compaction from heavy vehicles can kill roots. When tree roots are damaged by any of these causes, the tree begins to decline. The first symptoms may be leaf scorch.

Trees damaged by herbicides usually have leaves that are curled or cupped or have turned yellow or brown along the edges, depending on the kind of herbicide that caused the injury and the amount of exposure the trees received. Herbicides can drift through the air or move through the soil and injure trees some distance from where they were applied. Herbicide injury in trees is most often associated with the use of lawn weed killers. Herbicide exposure through the soil is longer lasting and usually more damaging than exposure through the air. Always make sure not to apply granular lawn weed killers too close to your trees.

A tree is girdled when something is tightly wrapped around the trunk or stem. Girdling chokes off the flow of water and nutrients between the roots and branches, as well as preventing food produced in the leaves from reaching the roots. Symptoms of stem girdling roots include leaf scorch, early fall color, and early leaf drop.

If you don’t recognize any of the above mentioned scenarios, it might also be an injury, or a bacterial or fungal disease. In any case, if your trees appear to be declining, it is best to let a specialist (an arborist) diagnose the situation before it is too late.

I planted Hippeastrum in October and it bloomed spectacularly in March. When it finished, I cut off the stem about an inch above the leaves. I would love to rejuvenate the flowers for next year. What do I do next? Leave the leaves on for now and fertilize twice a week until this fall? Is it better to plant it in my garden once the weather warms up or just leave it in its pot? How much sun does it require?

Hippeastrum, or amaryllis, is one of the most spectacular flowers for indoor forcing here in cold, bleak Michigan winters. You are on the right track for rejuvenation. Continue to fertilize until the foliage dies. Remove the bulb from the pot, dry it off, remove any side bulbs, and store in a cool place in dry peat moss. It is best not to put the bulb in your garden, as you will interfere with its natural life cycle. They are native to tropical zones, places whose winters are our summers. The bulb needs a period of rest, after the leaves have worked hard to photosynthesize food stored then in the bulb. Come October, you can repot the bulb in a well-drained container. Don’t water until you start seeing growth. Then water sparingly once you start seeing new growth from either the flower stalk or the foliage. They enjoy a sunny exposure, being the tropical beauties they are, but will admirably tolerate dappled shade or part day sun.

Amaryllis in containers can be placed outdoors in spring when all threat of frost is past. Just start it in a shady spot, gradually moving it into more sun over a week or so. Keep them evenly watered but not saturated, and fertilized once a month.

I have an 18-year old lawn from sod with assorted landscaping and irrigation. The soil is primarily clay. I have acquired a nighttime guest this spring in an area approximately 20 by 20 feet underneath a red maple tree. As soon as the snow was gone, I began to notice small holes in the grass in this area as if an animal was looking for food. The area has gradually been destroyed as if the soil were being prepared for planting. I have fertilized regularly, used weed control, grub and insect control and do not see any evidence of insects.

From the clues at the scene of the crime, it sounds like your midnight marauder is one very persistent skunk. You have a good news, bad news situation. The skunk is doing you a favor by eating plant-eating insects and larvae. However, their table manners leave your yard looking pockmarked. They not only love grubs but also worms and windfall fruit. They have no qualms about tearing up your lawn looking for them.

Skunks are creatures of habit, following a very methodical path in their foraging. You say you have applied grub and insect controls. You might check again under the lawn to see if they have been effective. The best way to discourage the skunk is to eliminate its food source. Remove a square foot of turf about an inch below the roots in the area being attacked to see if there are any grubs, cutworms or other succulent larvae drawing the skunk’s attention. If this patch test yields a grubless verdict, then you are dealing with animal habit. You may need to have the animal live-trapped by a professional and removed from the area. Please note this method isn’t foolproof because skunks are happy suburbanites. Another skunk can easily move into the vacated territory. However, with the current animal’s removal, you might break the foraging cycle long enough to eliminate the grubs and re-establish a healthy lawn, taking it off the skunk menu.

We are having an erosion problem with two large boulder walls in our condo association. We want to preserve the looks of the boulders and not cover them up completely, but yet need to retain the soil around the rocks. We thought about vinca, pachysandra, vetch, etc.

There are several ground covers or filler plants that would work well to control the erosion and compliment the boulder wall. The plants chosen will depend on the amount of available light. First review the four categories of light and then choose your plant or plants. All recommendations reflect low maintenance plants that will not completely cover the boulders, help control the erosion and will take dry soil, because of the hill condition.

The four light conditions are dense shade that has no direct sunlight, and is mostly reflected light under trees or evergreens, or against a north wall. Moderate shade is filtered or reflected light with almost no direct sun. Part sun has filtered sun and a few hours of direct sun. A minimum of six hours of direct sun is considered full sun.

Some nice plants for direct to part sun that also have wonderful blooms include the herb thyme (several varieties with fun fragrances like lemon or coconut), hens and chicks (Sempervivum) grown for their succulent foliage, low-growing sedums with red blooms like ‘Bronze Carpet’ or ‘Dragons Blood,’ and candytuft (Iberis sempervirens) with white blooms.

For part sun to moderate shade try the hardy and fleshy ice plant (Delosperma nubigerum) with nice yellow blooms in May.

Plants that will grow in many light and adverse soil conditions include sweet woodruff, which thrives in dense shade to part sun and blooms in spring. Also, several varieties of Lamium that thrive in full sun to moderate shade bloom in spring and sometimes rebloom in fall. My favorite is ‘White Nancy’ which has white blooms in spring and silvery foliage that “glows” in the dark.

Many of the plants mentioned above can be purchased by the flat to make them more economical to plant in large areas.

Of the plants you have already considered there are some things to keep in mind. Vinca spreads easily and will quickly force out native woodland plants if your wall is not in a completely landscaped area. Similarly, vetch is an extremely vigorous invasive plant. Pachysandra, although not as invasive as the other two, is just not very suitable for growing on a wall.

Whichever plants you decide upon, keep them well watered until they get established, and plant with a slow-release fertilizer.

About 12 years ago I purchased a 1929 English Tudor, which at one time had beautiful rose and perennial gardens. Unfortunately they were left to die out except for invasive star of Bethlehem. This has surrounded the house. In the past three years I have dug up every bed and sifted all the soil. All I did was disrupt them; every little baby developed into healthy adult bulbs. What must I do to rid the beds of these menaces? They come up like weeds every spring.

There’s no sugarcoating this…You do have some work ahead of you. Here are several options, listed in order of effort.

1. Continue to dig them out every spring; this could take years to get rid of them.
2. While a little time consuming, using boiling water is very effective without using chemicals. (Be sure you wear a long-sleeved shirt, closed-toe shoes, and long pants to protect your skin should any of the water splash on you.) If the tubers are several inches under the soil, stir them up enough to get the tubers closer to the surface, and pour the water on them at very close range. Watch for new growth and repeat.
3. If you have not already replanted the area(s), cover them with cardboard (or a thick layer of newspaper) and a heavy layer of mulch for one entire growing season. The cardboard and newspaper can be turned under the following year as compost. Any plant must have light to survive and store food; depriving them of that results in death. But these guys don’t go down easy; some may survive and will require digging out or boiling water. Another option is to cover the area with thick black plastic.
4. Finally, spray with a vegetation killer and wait. Spray any survivors. This means everything dies, including many living organisms that are good for the soil. This type of product also leaches into the soil because the plants don’t usually consume all of it. Be doubly cautious about the quantity used and mindful of any nearby water sources.

Are all hydrangeas perennials? If not, how can you tell which are or which are not?

All hydrangeas are either woody or herbaceous perennials. The problem for northern states like Michigan is that not all hydrangeas are winter hardy, and are not able to take the Zone 5 winters that can dip to -20 degrees. We seem to crave those bigleaf hydrangeas (Hydrangea macrophylla) with lovely pink and blue, large lacecaps. They do not do well in Zone 5 unless extremely well-sited. Once you travel south into Zone 6 and beyond, the plants become more common and successful. In Zone 5, these hydrangeas should be considered container plants to be brought inside for the winter.

There is a climbing hydrangea (H. petiolaris), which is winter hardy here and can be used both as a shrub or a disguise for a large structure. It produces a white blossom in late June that is fragrant and lasts for two weeks or more. Two other hydrangeas with a large shrub or spreading tree habit are panicle hydrangea (H. paniculata) and oakleaf hydrangea (H. quercifolia). Both are winter hardy and work well in a larger landscape. In both cases, it is important to obtain a named variety from a reputable nursery to insure plant characteristics live up to your expectations.

We get dead circles in our grass. Inside the circle, the grass looks fine. We have had the grass replaced, aerated, and seeded, yet the problem keeps returning. How do we fix this?

The symptoms you describe are characteristic of yellow patch (caused by a Rhizoctonia fungus), sometimes known as “frog eye” or “summer patch.” It occurs during hot, dry and windy weather near the end of summer. Drought-stressed, shallow-rooted Kentucky bluegrass lawns are the most susceptible. It often shows up near paving or parts of the lawn that dry out first.

You need to review your lawn maintenance and cultural practices. Overuse of nitrogen fertilizers and excess thatch can make the problem worse. By aerating, you have taken a step to reduce thatch and improve water penetration. Make very sure that your mower blades are sharp, and that the grass is mowed no shorter than 2-1/2 inches. Mowing too short sets the lawn up for weeds and further disease. When you water, water deeply to wet the entire root zone and water consistently. Do not let the turf dry out. Betting on Mother Nature to be cooperative with her rain showers can often make the homeowner the loser in the “turf stakes.” Apply less nitrogen, particularly in midsummer, on Kentucky bluegrass lawns.

If you find you must reseed, select resistant varieties. Studies have also shown that simply adding a small percentage of perennial ryegrass to bluegrass can greatly reduce the problem.

We are able to get free ash tree chips from local landscapers. Most of the chips are less than 1 inch, but there are occasionally large wood chunks. Are these chips safe to use? Will we be bringing the emerald ash borer (EAB) into our yard? We do not have any ash trees, but can these insects cause harm to other plants?

Using the chips is not likely to introduce the ash borer, but it is possible. When Genesee County was outside of the EAB quarantine zone, some trees became infested near the processing plant that was burning the ash chips.

If you live outside of the quarantine zone (note that virtually all of southeastern Michigan is in the quarantine zone), do not bring in ash chips on the small chance of accidental infestation. If you live within the quarantine zone, feel free to use the chips.

So far there has been no known instances of the EAB infesting any plants other than ash trees.

When I lay down newspapers to smother weeds and build a new garden bed, is there any danger of the newspaper inks leaching into the soil and being toxic?

Today’s newspaper ink is largely based on soybean oil. It has been on the newspaper market since 1989. You might have noticed if your hands are moist when reading the paper that the ink more readily smudges. If you have any questions about the particular newspaper you are using, call them and ask what kind of ink they use.

It is preferable to use only the black and white newsprint for smothering weeds or grass to create a new garden bed. Some of the older colored inks contained petroleum-based solvents or oils with pigments containing toxic substances. Although, with society’s emphasis on recycling, most newspapers are now using vegetable dyes even for colored advertisements and the comics. Again, check with your newspaper of choice.

Any glossy pages, however, are covered with a clay coating that retards decomposition. So do NOT use or compost with any of the advertising inserts. These ad inserts are printed by someone other than the newspaper and can contain the heavy metal inks toxic to microorganisms.

If you are preparing a vegetable bed, you might feel safer cultivating the weeds and soil manually. However, the soy-ink newspaper smother is still one of the fastest ways to make a new bed ready for the eager home gardener.