Late summer (late August to mid-September) is an excellent time to plant many perennials. It is also a good time to move or divide perennials, such as peony, daylily, garden phlox, and oriental poppy. Perennials planted in late summer should be mulched with several inches of straw, pine needles, or other materials in late November. Mulching helps prevent repeated freezing and thawing of the soil that can heave plants out of the ground. Plants heaved out of the soil may be severely damaged or destroyed due to drying of the exposed plant crowns and roots.
While they are both called "soaps," dish soap (like Dawn or Palmolive) is not a replacement for insecticidal soap.
Dish soap is actually more accurately classified as a detergent, not a soap. Soap is a molecule composed of salts (such as potassium or sodium) and fatty acids. Detergents are derived from petrochemicals and are a different type of molecule.
While dish soaps (detergents) can cause issues for insects, their effect on pests is limited and highly variable. Dish soap is also much more likely to cause damage to the plant, such as phytotoxicity. Insecticidal soap is a true soap (usually potassium salts of fatty acids) created specifically to target pests. They work on contact by damaging the insect's cell membranes. The cell contents are able to leak from the damaged cells, and the insect dies. They have no residual action and easily wash away. This is what makes insecticidal soaps a safer pesticide option compared to traditional pesticides. This also means, however, that insecticidal soaps have to be applied frequently to control insect populations as they only affect the insects they come in contact with. Any hiding insects or those that emerge after the application would be unaffected and would require a second (or third, etc.) application to kill them.
The butterfly weed (Asclepias tuberosa) is a member of the milkweed family. Plants grow 2 to 3 feet tall and produce flat-topped clusters of bright orange flowers from July through September. Their flowers attract several butterfly species, hence the common name.
Butterfly weed is easy to grow. It performs best in full sun and tolerates heat, drought, and infertile soils. The butterfly weed possesses a long taproot. Because of its long taproot, division is difficult and not recommended. The butterfly weed is typically propagated by seeds.
While more demanding than many other perennials, the Lenten rose (Helleborus x hybridus) can be successfully grown in Iowa. The Lenten rose requires a fertile, well-drained soil in partial shade. Also, choose a site protected from strong winter winds. The evergreen foliage of the Lenten rose may become scorched or tattered when subjected to strong winds in winter.
Most hostas do not need winter protection if they have been in the ground for at least one full growing season. However, a winter mulch is often beneficial to hostas planted in late summer or early fall. Repeated freezing and thawing of the soil in the winter months may heave late planted hostas out of the ground, causing serious damage. An application of several inches of clean, weed-free straw or pine needles in mid to late November will help to protect late summer/early fall planted hostas over winter.
Some perennials, such as garden peonies, can be left undisturbed for 50 or more years.
Others need to be divided periodically to contain their spread or to rejuvenate declining plants. Vigorous growing perennials include:
gooseneck loosestrife (Lysimachia clethroides)
obedient plant (Physostegia virginiana)
bee balm (Monarda didyma)
They grow so rapidly that they begin to crowd out neighboring plants within a few years. Gooseneck loosestrife and other vigorous growers should be divided every 2 to 3 years. After dividing the perennials, replant some of the divisions, give others to relatives or neighbors, and discard remaining plants in the compost pile.
In contrast, the performance of some perennials, such as bearded iris (Iris hybrids), begins to decline after several years. If not divided every 3 to 5 years, bearded irises usually don’t bloom well because of overcrowding. Declining perennials should be divided to rejuvenate the plants.
Peonies are usually sold as bare-root or container-grown plants. Bare-root plants (often sold via mail-order) are best planted in late summer or early fall. Container-grown peonies (often sold from local garden centers) can be planted in the landscape at any time from spring to early fall.
Powdery mildew is a common disease of garden phlox (Phlox paniculata). The fungal disease produces a grayish white coating on the leaves. Infected leaves eventually turn yellow and then brown. Initial symptoms appear on the lower leaves with the disease progressing upward.
Powdery mildew is a common issue on garden phlox
Powdery mildew is most commonly found on plants growing in shady areas and in crowded plantings with poor air circulation. Optimal conditions for powdery mildew are cool nights followed by warm days.
Cultural practices can reduce the severity of powdery mildew on garden phlox. The amount of disease inoculum can be reduced by cutting off and removing diseased plant debris in the fall. Plants growing in shady locations should be moved to a sunny site. In overcrowded plantings, improve air circulation by digging and dividing perennials.
While cultural practices are helpful, fungicides may be necessary to control powdery mildew on garden phlox. To be effective, fungicides should be applied at the first sign of the disease and repeated on a regular basis.
Selecting and planting powdery mildew-resistant varieties is one of the best ways to reduce issues with powdery mildew. The following cultivars possess good resistance to powdery mildew:
‘Ditomdre’ (Coral Crème Drop™) (salmon-pink flowers, dark stems)
‘Shortwood’ (pink flowers)
‘Babyface’ (pink flowers with dark pink centers)
'Frosted Elegance' (white flowers with pink centers; variegated foliage)
'John Fanick' (light pink flowers with dark pink centers)
'Peppermint Twist' (flowers with pink and white stripes)
'Katherine' (lilac blue flowers with white star-shaped centers)
'Orange Perfection' (salmon-orange flowers, shorter than most cultivars)
*The resistance or susceptibility of garden phlox varieties to powdery mildew varies within the United States. A variety that possesses good resistance to powdery mildew in the Midwest may be susceptible to powdery mildew in other regions of the country.
The iris borer is a serious pest of bearded irises. The mature stage of the iris borer is a grayish moth. Female moths lay eggs on iris foliage and other nearby plants in late summer/early fall. The eggs hatch the following spring. The small larvae (caterpillars) bore their way into the iris foliage and feed on leaf tissue. Over time, the larvae tunnel down through the leaves and into the rhizomes. The caterpillars continue to feed inside the rhizomes and eventually destroy much of it. When fully grown, the larvae move into the soil and pupate. Adults (moths) emerge in late summer.
Bacterial soft rot often invades rhizomes damaged by iris borers. Rhizomes infected with bacterial soft rot become soft and foul-smelling.
Iris borers can be controlled by sanitation and the timely application of insecticides. Remove and destroy dead iris foliage in late fall or early spring. This will eliminate many of the iris borer eggs. An insecticide should be applied in spring when the new shoots are 4 to 6 inches tall. An application of an insecticide at this time should destroy small iris borer larvae before they have the opportunity to bore into the iris foliage. Products that contain acephate, permethrin, or spinosad should be effective. As always, carefully read and follow label directions when using pesticides.
Ornamental grasses are low-maintenance perennials. Most thrive in sunny sites and there are species that can grow in dry, well-drained, or wet soils. While small in the nursery, many can get quite large in just a couple of years, so check the labels carefully for mature size and site preferences. Once established, grasses need minimal care requiring watering only in times of drought. Ornamental grasses rarely need fertilizer. If growth is pale, weak, or floppy, scatter some granular fertilizer around them in the spring.
Let grasses and their ornamental flower heads stand all winter. Even when tan and dead, they are quite attractive after a snowfall. Cut back ornamental grasses in early spring before the new growth appears. Division is sometimes necessary to keep ornamental grasses thriving in the landscape. If the center of the clump begins to thin or die out, divide in early spring just as the new growth appears.
Crabgrass is an annual weed. In flower and vegetable gardens, hoeing and hand pulling are the best control options. When cultivating the garden, avoid deep tillage. The roots of many vegetables and flowers grow near the soil surface. Deep cultivation will cut off some of these roots. Also, deep cultivation will bring deeply buried weed seeds to the soil surface where they can germinate. Hand pulling is best done after a good rain.
Most garden areas, including the lawn, vegetable garden, and perennial garden, perform best when they receive an inch of water each week. When this is not supplied by rain, the gardener must do it using a hose, bucket, or sprinkler.
Determine How Much Water is Needed
How Much Water Provides 1-Inch of Irrigation?How Much Water is Needed?
It takes 0.623 gallons of water to supply 1 inch of water to 1 square foot of garden space.
To determine how many gallons of water are needed for your garden, multiply the area of your garden by 0.623. If you are watering a specific tree, shrub, or other plant, find the area of the root zone under the plant.
For example, a newly planted tree with a root zone area of 16 square feet would require ~10 gallons of water to deliver 1 inch of water to the root zone (16 sq ft × 0.623 gallons per sq ft = 9.97 gallons ≅ 10 gallons)
If watering by bucket or watering can, measure out this amount and apply it to the area slowly enough to prevent runoff.
Determine How Much Water is Supplied
Hose
When watering with a hose, you need to determine how much water it supplies next. Use the nozzle you plan to use while watering, and turn the hose on to the water pressure you plan to use while watering. In most cases, this is not all the way on, as a lot of water will run off if it is supplied too quickly.
Determine how many minutes and seconds it takes to fill a five-gallon bucket. Divide the bucket's capacity by the time to fill it to determine the gallons per minute.
How Much Water Does the Hose Supply?
For example, it takes 2 minutes and 26 seconds to fill a five-gallon bucket, so the hose delivers 2.1 gallons per minute (5 gallons ÷ 2.43 minutes = 2.1 gallons per minute; remember, 26 seconds is 0.43 minutes; 25 ÷ 60 = 0.43).
Soaker Hose
For a soaker hose, the flow rate is provided on the package in gallons per hour (GPH). If the hose provides a flow rate per foot (GPH per foot), multiply that by the hose length to determine how many gallons of water it delivers. To get gallons per minute, divide the GPH by 60. While the flow rate will vary with water pressure, this calculation is typically close enough for home garden watering.
Determine the Watering Time Needed
Using the amount of water needed and the flow rate, you can calculate how long to run the hose to get the required amount of water. Take the number of gallons needed divided by the gallons per minute to get the number of minutes needed to water.
How Long to Irrigate?
For example, the watering time needed for a newly planted tree with
16 square feet of area
requiring 9.97 gallons of water
provided using a hose that delivers 2.1 gallons per minute
would be 4 and 42 seconds (9.97 gallons ÷ 2.1 gallons per minute = 4.7 minutes or 4 minutes and 42 seconds; remember, 0.7 minutes is 42 seconds; 60 × 0.7 = 42).
Watering Using a Sprinkler
Watering using a sprinkler or soaker hose is more straightforward. To calculate the time needed to deliver an inch of water, start by setting up the sprinkler to cover the area you wish to irrigate.
Then set up several shallow, flat-sided containers in the spray. Turn the water on at the pressure you plan to use while watering and determine how long it takes to fill them to one-half inch. Multiply the number by 2 to get the time needed to deliver 1 inch of water to the irrigated area.
Knowing the area of the garden bed or lawn is necessary for applying fertilizers or pesticides, determining how much mulch is needed, or determining the number of plants needed to fill a space.
Websites and phone apps are also available to determine the area of your garden bed or yard using online maps. One example is this site: Measure My Lawn.
Otherwise, the area can be determined using a series of measurements. Use the information below to find the area of your garden bed or lawn based on its shape.
A simple rectangular bed is one of the most straightforward bed shapes to determine the area. Simply, multiply its length by its width.
Area = length × width
Example: Finding Area of Rectangular-shaped Garden Bed
Area of Triangular Bed
To determine the area of a triangular-shaped planting bed, measure the length of the base and then the height (the distance from the top point down to the base). Then, use the formula below to determine square footage.
Area = base × height × 0.5
Example: Finding Area of triangular-shaped Garden Bed
Area of Circular Bed
For a round planting bed, multiply pi (π=3.14) by the radius squared. The radius equals the distance from the center of the circle to the edge.
Area = 3.14 × radius2
Example: Finding Area of circle-shaped Garden Bed
Area of a Semicircle Bed
For a semicircle (also called a half-moon or half-circle) bed, start by finding the length of the radius. For a semicircle, the radius equals the length of the flat/straight edge divided by two. Then, use the formula for the area of a circle and multiply it by one-half.
Area = 3.14 × radius2 × 0.5
Example: Finding Area of Semicircle-shaped Garden Bed
Area of Oval (Elliptical) Bed
An oval bed (more accurately referred to as an ellipse) can be found after collecting two measurements. Measure from the center of the bed to the furthest edge point. This is called the major radius. Then, going back to the center, at a right angle to the major radius, measure from the center to the bed edge - this is the minor radius. Multiply those two numbers by pi (π=3.14) to get the area.
Area = 3.14 × major radius × minor radius
Example: Finding Area of Oval-shaped Garden Bed
Area of an Irregular-Shaped Bed
Many garden beds have a more irregular shape. For beds comprising straight lines, simply break the bed apart into triangles, rectangles, and/or semicircles. Find the area of each piece and add them together.
For more complex irregular shapes, such as a bed shaped like a kidney bean, the bed area can be estimated with decent accuracy by first gathering several measurements. Find the length of the longest line within the shape - this is the length line. Along this length line, measure perpendicular width lines (at a 90° angle) to the length line. The distance between the width lines (called the segment width) must be equal. For example, you might measure the width of the bed every 3 feet along that length line. You can measure any number of width lines as long as they are equidistant from each other. The more width lines you measure, the more precise your area calculation will be. To find the area, add all of the width line lengths together and multiply that by the segment width.
Area = (sum of all width lines) × segment width
Example: Finding Area of Irregular-shaped Garden Bed
Example: Finding Area of Complex Irregular-shaped Garden Bed
Harvest the seed pods of butterfly weed when the pods begin to split. Seeds can be sown directly outdoors in late fall or started indoors.
When sowing seeds outdoors, work up the soil in a protected location in early to mid-November. Scatter the seeds over the prepared seed bed and then cover the seeds with approximately 1/4 inch of soil. The cold, moist conditions over winter improve seed germination. Seedlings should emerge in spring. Carefully transplant the seedlings to their permanent locations when the seedlings are 3 to 4 inches tall.
To start seeds indoors, fill a flat with a commercial germination medium (such as Jiffy Mix). Moisten the medium. Scatter the seeds over the surface of the germination medium and lightly press the seeds into the material. Cover the seeds with an additional 1/4 inch of the germination mix. Carefully moisten the additional material. Slide the flat in a plastic bag and place the bagged flat in the refrigerator. Leave the flat in the refrigerator for 4 to 6 weeks. After 4 to 6 weeks, remove the flat from the refrigerator and place it in an area with a temperature of 70 to 75 degrees Fahrenheit. Seeds should begin to germinate in 3 to 4 weeks. (If no seedlings appear after 4 weeks, place the flat back in the refrigerator for another 4 to 6 weeks and repeat the process.) Take the flat out of the plastic bag as soon as seedlings appear and place the flat under fluorescent lights in a 60 to 65 degree Fahrenheit location. Transplant the seedlings into individual pots when the seedlings are 1 to 2 inches tall. Continue to grow the seedlings indoors under fluorescent lights for several more weeks. Prior to planting outdoors, place the seedlings outdoors in a shady, protected location and then gradually expose the seedlings to longer periods of direct sun. Plant the seedlings in their permanent locations after they have hardened outdoors for 10 to 14 days.
Cut the plants back to within 4 to 6 inches of the ground a few days after a hard, killing frost. Then carefully dig up the canna clumps with a spade or garden fork. Leave a small amount of soil around the cannas. Allow them to dry for several hours. Afterwards, place the cannas in large boxes, wire crates, or in mesh bags. Store the cannas in a cool (40 to 50 degree Fahrenheit), dry location.
Elephant’s ear (Colocasia esculenta) is a tropical plant grown for its huge, heart-shaped leaves. Dig up the plants after the first fall frost. Cut off the foliage. Dry the tubers in a warm, dry location for 1 or 2 weeks. After drying, bury the tubers in peat moss or wood shavings and store them in an area with a temperature of 70 to 75 degrees Fahrenheit.
Carefully dig up the plants with a spade in late summer/early fall. Gently shake off the soil from the bulb-like corms. Then cut off the foliage 1 to 2 inches above the corms. Dry the corms for 2 to 3 weeks in a warm, dry, well-ventilated location. When thoroughly dry, remove and discard the old dried up mother corms located at the base of the new corms. Remove the tiny corms (cormels) found around the base of the new corms. Save the small corms for propagation purposes or discard them. Place the corms in mesh bags or old nylon stockings and hang in a cool, dry, well-ventilated location. Storage temperatures should be 35 to 45 degrees Fahrenheit.
Carefully dig up the tuberous begonias within a few days of a killing frost. Leave a small amount of soil around each tuber. Cut off the stems about 1 inch above the tubers. Place the tubers in a cool, dry area to cure for 2 to 3 weeks. After curing, shake off the remaining soil. Place a layer of peat moss, vermiculite, or sawdust in a small cardboard box. Lay the tubers on the storage medium, then cover the tubers with additional peat, vermiculite, or sawdust. Store the tubers in an area with a temperature of 40 to 50 degrees Fahrenheit. Do not allow the tubers to freeze.
Most garden areas, including the lawn, vegetable garden, and perennial garden, perform best when they receive an inch of water each week. When this is not supplied by rain, the gardener must do it using a hose, bucket, or sprinkler.
Determine How Much Water is Needed
How Much Water Provides 1-Inch of Irrigation?How Much Water is Needed?
It takes 0.623 gallons of water to supply 1 inch of water to 1 square foot of garden space.
To determine how many gallons of water are needed for your garden, multiply the area of your garden by 0.623. If you are watering a specific tree, shrub, or other plant, find the area of the root zone under the plant.
For example, a newly planted tree with a root zone area of 16 square feet would require ~10 gallons of water to deliver 1 inch of water to the root zone (16 sq ft × 0.623 gallons per sq ft = 9.97 gallons ≅ 10 gallons)
If watering by bucket or watering can, measure out this amount and apply it to the area slowly enough to prevent runoff.
Determine How Much Water is Supplied
Hose
When watering with a hose, you need to determine how much water it supplies next. Use the nozzle you plan to use while watering, and turn the hose on to the water pressure you plan to use while watering. In most cases, this is not all the way on, as a lot of water will run off if it is supplied too quickly.
Determine how many minutes and seconds it takes to fill a five-gallon bucket. Divide the bucket's capacity by the time to fill it to determine the gallons per minute.
How Much Water Does the Hose Supply?
For example, it takes 2 minutes and 26 seconds to fill a five-gallon bucket, so the hose delivers 2.1 gallons per minute (5 gallons ÷ 2.43 minutes = 2.1 gallons per minute; remember, 26 seconds is 0.43 minutes; 25 ÷ 60 = 0.43).
Soaker Hose
For a soaker hose, the flow rate is provided on the package in gallons per hour (GPH). If the hose provides a flow rate per foot (GPH per foot), multiply that by the hose length to determine how many gallons of water it delivers. To get gallons per minute, divide the GPH by 60. While the flow rate will vary with water pressure, this calculation is typically close enough for home garden watering.
Determine the Watering Time Needed
Using the amount of water needed and the flow rate, you can calculate how long to run the hose to get the required amount of water. Take the number of gallons needed divided by the gallons per minute to get the number of minutes needed to water.
How Long to Irrigate?
For example, the watering time needed for a newly planted tree with
16 square feet of area
requiring 9.97 gallons of water
provided using a hose that delivers 2.1 gallons per minute
would be 4 and 42 seconds (9.97 gallons ÷ 2.1 gallons per minute = 4.7 minutes or 4 minutes and 42 seconds; remember, 0.7 minutes is 42 seconds; 60 × 0.7 = 42).
Watering Using a Sprinkler
Watering using a sprinkler or soaker hose is more straightforward. To calculate the time needed to deliver an inch of water, start by setting up the sprinkler to cover the area you wish to irrigate.
Then set up several shallow, flat-sided containers in the spray. Turn the water on at the pressure you plan to use while watering and determine how long it takes to fill them to one-half inch. Multiply the number by 2 to get the time needed to deliver 1 inch of water to the irrigated area.
Perennial plants can be cut back in fall after the foliage has been destroyed by a hard freeze. Compost the plant debris. While this work can be done, it is not necessary to clear cut the perennial garden after the first freeze of the season.
Leaving Organic Material
Leaving the leaves, stems, dried flowers, and seed heads of many perennials provides more interest through the winter months. Leaving the plant materials also provides an extra layer of protection for the crown and root system of the perennial. Plus, the dead stems and leaves collect fallen leaves adding even more protection. Leaving the plant material in place and removing it in early spring instead of fall also helps provide food and protection to native pollinators, beneficial insects, and wildlife, like birds.
While it is largely beneficial to leave foliage in place through winter, removal of plant material in the fall after it has naturally died back should be done for those perennials that had disease or insect pest issues during the summer. Additionally, those perennials that tend to be weedy or spread aggressively by seed benefit from late season deadheading and clean up to prevent them from being too weedy.
Frost Heaving
Leaving plant debris in place over the winter months can help those shallow rooted perennials that may frost heave. Frost heaving happens when the freeze-thaw cycle of the upper layer of soil works the crown and root system of the perennial plant out of the ground. If more protection is needed to prevent frost heaving, apply about four inches of mulch over the crown of the plant after the ground freezes, typically by late November in much of Iowa. Do not place the mulch on too early as it can slow plants from going dormant and make them more susceptible to damage from cold temperatures. Remove the excess mulch “blanket” in early spring as soon as the top layer thaws, typically around mid-March in much of Iowa.
Mulching Tender Perennials
Tender perennials and perennials planted in late summer/early fall should also be mulched to prevent injury. These plants can also be protected with cages placed around the plants and filled with straw, pine needles, or chopped corn stalks. As with extra mulch, place the protective layer late in the fall season and remove it in early spring. A 6- to 8-inch-layer should be adequate for most perennials. Do not use Styrofoam cones or domes as they can cause premature warming in the early spring bringing plants out of dormancy early and making them more susceptible to cold damage. Additionally, most plants will not fit under these cones without extensive pruning and it is better to prune in spring rather than fall.
There are several species of fountain grass. Perennial fountain grass (Pennisetum alopecuroides) is a perennial grass. It is hardy in much of Iowa. Annual fountain grass (Pennisetum setaceum) is a widely grown annual grass. The most popular annual cultivars are those with reddish purple foliage, such as ‘Rubrum.’ Annual fountain grass will not survive the winter in Iowa.
Many peony plants produce few, if any, flowers the first spring. In fact, it’s advisable to pinch off any flower buds that develop the first spring to promote root and foliar growth. Flower bud development requires a great deal of the peony plant’s energy. Initially, the young plant’s energy should be directed to root and foliar growth to aid plant establishment. Peony plants should be blooming well by the third or fourth year.
The white, powdery material on the peony foliage is powdery mildew. Powdery mildew is a fungal disease. Powdery mildew occurs on a large number of plants (peonies, lilacs, viburnums, roses, garden phlox, bee balm, turfgrass, and many others). Fortunately, powdery mildew seldom causes serious harm to plants. The damage is mainly aesthetic.
Powdery mildew tends to be more common on peonies growing in partial shade. Moving peonies growing in partial shade to a sunny location often helps reduce the incidence of powdery mildew. Late September is an excellent time to move peonies in Iowa.
There are several factors which may cause peonies to bloom poorly. Peonies perform best in areas that receive at least 6 hours of direct sun each day. Peonies that receive less than 4 hours of direct sun will not bloom well. Plants growing in a shady location should be transplanted to sunny site in September. Peonies planted too deeply often fail to bloom well. When planting peonies, position the peony buds 1 to 2 inches below the soil surface. Peonies that are planted too deeply produce lush foliage, but don’t bloom well. Recently planted or divided peonies may not bloom well for 2 or 3 years. The new plants need to grow stronger before they are capable of blooming well. Also, premature removal of peony foliage in July or August weakens plants, resulting in few flowers the following spring.
After the first frost in the fall, we are sometimes compelled to clean up the dead plant debris. While perennial plants can be cut back in fall after the foliage is destroyed by a hard freeze, it is often beneficial to wait until spring.
Benefits of Waiting Until Spring
Leaving the leaves, stems, dried flowers, and seed heads of many perennials provides more interest through the winter months. Leaving the plant materials also provides an extra layer of protection for the perennial's crown and root system. Plus, the dead stems and leaves collect fallen leaves, adding even more protection. Leaving plant material in place and removing it in early spring rather than fall also helps provide food and protection for native pollinators, beneficial insects, and wildlife, such as birds.
When to Cut Back in the Fall
While it is largely beneficial to leave foliage in place through winter, removing plant material in the fall after it naturally dies back should be done for perennials that had disease or insect pest issues during the summer. Additionally, those perennials that tend to be weedy or spread aggressively by seed benefit from late-season deadheading and clean up to prevent them from being too weedy.
The symptoms on your bee balms (Monarda spp.) are most likely due to powdery mildew. Powdery mildew is a common fungal disease on bee balms. Symptoms are most severe on overcrowded plants and those growing in partial shade.
Cultural practices can reduce the severity of powdery mildew. When planting bee balms, select a site that receives at least 6 hours of direct sun each day and space plants 2 to 2½ feet apart. Move plants growing in partial shade to a sunny location. Divide bee balms every 2 to 3 years to prevent overcrowding. Remove and destroy disease-infested plant debris in fall. If cultural practices fail, fungicides can also be used to control powdery mildew.
Probably the best way for home gardeners to avoid the annoying problem of powdery mildew is to select and plant mildew resistant varieties. Varieties that possess good to excellent resistance to powdery mildew include:
The foul-smelling objects are likely stinkhorns. Stinkhorns are a type of fungus or mushroom. The common name is derived from their appearance and smell. Stinkhorns usually appear in cool, wet periods in late summer and early fall.
Several species of stinkhorn are found in Iowa. The fungi live off dead organic matter and are commonly found in mulched areas in the landscape. Stinkhorns start off as an egg-like, golf ball-sized structure in the soil. As the fungus develops, a stalk grows upward and is topped with a slimy cap coated with a mass of olive green to brown spores. The putrid smell of the stinkhorn cap attracts flies and other insects. The flies and other insects crawl on the stinkhorn, get covered with slime and spores, then fly away to other areas, disseminating the spores. Stinkhorns range from about four to eight inches in height.
Stinkhorns are not poisonous or harmful to plants or people. Eventually, the stinkhorns wither away and disappear. Individuals can rake up and discard the fungi if their appearance or smell are bothersome.
