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Polk County Master Gardeners

Iowa State University Extension and Outreach in Polk County

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  • 11 Dec 2021 12:00 AM | Brenda Peshak

    Do you have a shrub in your yard that has been neglected? Is it in desperate need of some TLC? Wondering what to do with it?

    The answer is prune it!

    What is Pruning?

    • Selectively removing parts of a plant for the benefit of the entire plant.
    • Controls plant size and shape.
    • Keeps shrubby evergreens dense
    • Removes unwanted branches.

    Properly pruned plants should look natural. Pruning should be done with care and knowledge.

    When to Prune 

    Spring-flowering shrubs

    You don’t want to cut off next year’s flower buds unless you grow shrubs for their foliage and not their flowers. Spring-flowering shrubs, or those that bloom on last year’s growth. Examples are shrubs such as lilac and forsythia. The best time to prune it is in late winter or early spring (before mid April). Heavy pruning will reduce or eliminate your flower display for a couple of years, but you will end up with a healthier shrub.

    Once you have your spring-flowering shrub healthy again, maintain its health by lightly pruning it yearly right after it is finished flowering. Only light to moderate pruning will be needed and as the shrub will have time to recover and grow new flower buds before winter, next year’s flower display shouldn’t be impacted.

    Summer-flowering shrubs

    Some shrubs flower on new growth.  Those are branches grown during the current growing season. Examples: Japanese spirea and panicle hydrangea. These should be pruned in late winter or early spring regardless of whether you are maintaining your shrub or rejuvenating it.

    Inconspicuous flowering shrubs

    Some shrubs are grown for reasons other than their flowers. Their flowers may be inconspicuous, but they may have beautiful foliage, fruit, or bark. These shrubs should be pruned in late winter or early spring before new growth emerges.

    Evergreen shrubs

    Try to prune evergreen shrubs in early April before new growth begins. Examples: juniper and yew.  If you need to prune mid-summer, do so lightly. Avoid fall as evergreen shrubs pruned in fall are more susceptible to winter injury.

    How to Prune

    Maintenance Pruning

    First, remove any branches that are dead, diseased, or broken. These branches are not helping your shrub and could possibly be harming it.

    Next, check the structure of your shrub. Look for branches that are crossed.  Rubbing will cause wounds in plants just like humans get blisters. Next for branches that are competing and remove the least desirable one. If there are branches that are growing downward remove them as well. Also remove any limbs along the trunk that are larger in diameter than the trunk itself.

    Finally, remove any suckers or water sprouts. Suckers are shoots that are coming up from the roots or low on the trunk that are vigorous in nature. Water sprouts are vigorous branches that grow vertically. Both suckers and water sprouts are weakly attached to the plant. This means they can become problematical. These weedy branches can crowd desirable branches.  This will reduce flowering and fruiting. They can also change the plant’s structure making it prone to wind and ice damage.

    Pruning for Rejuvenation

    Rejuvenating a shrub takes time and a lot of patience. It will take three years to rejuvenate most shrubs and is not a quick fix.

    The first step is to remove any dead, diseased, or broken branches. Nothing good will come from them.

    Next, look at your shrub’s oldest, thickest trunks or stems. Prune out one third and ONLY one-third to the ground. This will encourage your shrub to put out new stems from its roots. Repeat this same process for the next two years. If each year you remove one third of the largest and oldest stems.  After three years you should have removed every original stem from the shrub.  Once all of the old, overgrown trunks are removed, switch back to maintenance pruning.

    Rejuvenating cane-growth shrubs

    Examples: spirea, forsythia, or honeysuckle have many stems or canes. If the shrub is healthy but overgrown rejuvenation can happen in a shorter time frame. Do this by cutting all the canes back as close to the ground as possible in early spring. The flowers for that season will be sacrificed.  However, the shrub will grow back within a growing season and look as good as new. Only use this method on cane-growth shrubs.


  • 11 Dec 2021 12:00 AM | Brenda Peshak

    Wanting to replace that invasive, non-native burning bush or barberry?

    Consider Aronia, it is a native shrub that does pretty much the same thing.

    Aronia is a woody shrub in the rosacea family from the Eastern US.  It offers masses of white blossoms in spring.  Showy edible berries in late summer.   Fall colors: red, orange, or mahogany. Aronia occurs naturally in woodsy bogs and wetland areas.  It also grows well in normal garden conditions. For lots of berries give it sun and mulch to conserve moisture.

    The shrubs tend to be upright and leggy.  Older shrubs will sprout suckers to form a grove.  If you don’t want to wait you can plant several at the same time.  In a mass the blossoms, berries, and fall foliage are striking. Older shrubs are quite drought-tolerant. If the shrub becomes crowded, cut about a third of the branches to the ground in order to leave the center open to sunlight. If you need to relocate the shrub, aronia is very forgiving.

    Common name

    Chokeberry it attests to the bitter taste of the berries.  They are so tart that eating them raw might make you choke! Which is why they are always made into pies, jams, jellies, and similar with lots of sugar!

    Aronia has a long history in the U.S. Reportedly, Native Americans, used the berries to cure colds and other ailments. They also pounded the berries into dried meat as a preservative.  The resulting compound was lightweight and useful for journeys—as Lewis and Clark (may have) discovered. Sadly, as the Native Americans were pushed onto reservations, this knowledge died out and wasn’t rediscovered until the middle of the 20th Century. Now, aronia is known as “superberry” or a “superfood” for its antioxidant properties. Indeed, aronia has had a spectacular resurgence in the 21st Century.

    Types of Aronia

    There are main two types of aronia—melanocarpa and arbutifolia. Both are about the same size—4’-8’ tall and about half as wide. One is more decorative than the other. Aronia melanocarpa has dark, glossy berries, the ones most often cited for their health-giving properties. Nurseries have created numerous cultivars of melanocarpa, but they’re pretty much the same. If you prefer a smaller shrub, however, ‘Iroquois Beauty’ grows only 2-3’—but has the same blossom, fruit, and fall color as the taller species. Because melanocarpa has recently become a “trendy” food, articles abound and information may need to be taken with a grain of salt. Be that as it may, studies have proved the berries’ healthful properties—and the shrubs remain useful in the landscape.

    Aronia arbutifolia, or red chokeberry, is usually considered the more decorative of the two. “Brilliantissima” offers glossy red berries that appear in clusters along the branches. Fruits are so dense that some think they’re seeing a bittersweet and not an aronia. While both varieties of aronia have good fall color, the foliage of ‘Brilliantissima’ turns a bright red (hence ‘red chokeberry’) that compares very favorably with burning bush. Both aronias have interesting bark in winter.

    Where to buy

    Local nurseries carry a limited number and selection, so online sources may be a better bet for a particular variety. Whatever you decide on, plant in as much sun as possible, water deeply and mulch the first year, then they should settle in.

    Good for Birds

    Birds love the plump berries of melanocarpa.  Birds tend to leave arbutifolia alone until later in the winter, which prolongs the fruit display. Both aronias are hardy to Zone 4, so they’re well suited to Iowa winters. Deer may browse the new growth, but a deterrent device will keep the damage to a minimum.

    So plant a native that has multi-season interest and an ancient history in America!

  • 3 Dec 2021 12:00 AM | Brenda Peshak

    Dutchmans Breeches

    Catch Ephemerals in Early Spring

    A walk in the woods in early spring can reward you with the sight and smell of some of nature’s loveliest—but fleeting—floral treasures—the native spring ephemerals. These beauties have a short above-ground presence. As soon as the air begins to warm and before the trees leaf out, they poke their heads out, form leaves and flowers, set seeds, then die back, retreating below the ground for another year. This process may take anywhere from a few weeks to a month or so, depending on the plant and the season. Because they don’t last very long, they’re called “ephemerals”—and they’re some of our favorite sights in early spring.

    Although these species prefer the moist, organic soil of the the forest floor, you can have them in your garden if you can re-create native conditions. Place your purchased plants in soil you’ve improved with liberal additions of compost (or even potting soil) in semi-or-dappled shade and ensure adequate moisture while they’re growing. No need to water after they’re gone dormant; however, keep the soil cool and moist with a mulch of chopped leaves, straw, chipped bark, or similar. Avoid peat moss as a top mulch, as it forms a crust water cannot penetrate.

    Avoid Insecticides Near Ephemerals

    If you do plant them, you’re helping out the early-season pollinators. Because there’s very little in bloom in early spring, bees, bee flies (especially Bombylius major), halictid bees (including green metallic bees), and muscid and syrphid flies depend on ephemerals for nectar. Likewise, ephemerals depend upon the pollinators for producing seed. Ants are also very important for dispersing seed. Because of their interdependence, it is very important to avoid insecticides around ephemerals.

    A partial list of native ephemerals includes:

    • Dutchman’s breeches (Dicentra cucullaria)
    • Jack-in-the-pulpit (Arisaema triphyllum)
    • Jeweled shooting star (Dodecatheon amethystinum)
    • Nodding trillium (Trillium cernuum)
    • Prairie shooting star (Dodecatheon meadia)
    • Rue anemone (Anemonella or Thalictrum thalictroides),
    • Squirrel corn (Dicentra canadensis), Trillium (Trillium grandiflorum)
    • Trout lily (Erythronium americanum), Virginia bluebells (Mertensia virginica)
    • Virginia spring beauty (Claytonia virginica)
    • Wood anemone (Anemone quinquefolia var. quinquefolia),
    • Wood poppy (Stylophorum diphyllum).

    Do not dig up ephemerals from the wild. Once the plants are gone from the forest, they seldom return; moreover, the pollinator population suffers from the loss of nectar. Most of the listed species are readily available from reliable bulb companies. Check their catalogs to see when to plant (mostly in fall). Because they disappear fairly soon, be sure to mark their location. Mask the bare spot with plants requiring like conditions—e.g., ferns, hostas, and similar.

    Even though they are with us only a short while every year, native spring ephemerals are some of the most well-loved and worthwhile plants in the garden. Be sure to treat yourself to a few!

  • 3 Dec 2021 12:00 AM | Brenda Peshak

    Fresh blueberries

    If you’re looking for a shrub that serves double (maybe triple!) duty, why not consider blueberries? Native to the U.S., blueberries offer not only delicious, health-giving fruit from mid-summer to early autumn–but also delicate white or pink flowers in spring, glossy, dark green foliage during summer, and gorgeous fall colors in oranges, reds, and yellows. What more could you ask from a plant!

    Blueberry round-up

    Iowa growers can choose between three varieties. Highbush blueberries grow from 5-9’ and offer good disease resistance. They also take up a lot of space. Half-high varieties have greater cold hardiness, grow around 3-4’, produce the same excellent fruit as their larger cousins, and are probably the most practical for home gardeners because their smaller size permits more bushes in the same amount of space—and, thus, greater fruit production. Half-high berries are a cross between highbush and lowbush varieties.

    Lowbush, or wild blueberries, some of which can survive to zone 2, usually top out around 18”. They’re suitable for containers or for in-ground planting. Some growers use them as a “fruitful” ground cover. If you opt for containers, choose large pots with drainage holes, fill them with acid soil mix, and place them in a sunny site. Protect them in winter by moving the pot to a sheltered location, burying to the pot rim, or covering with a thick wall of straw or wrapped in burlap or rose wrap. The idea is to protect the roots and the canes.

    Blueberry needs

    Blueberries require specific conditions. First is full sun. They’ll grow in part shade but will not prosper, so why not give them what they want in the first place—lots of sunshine!

    Second, an acid soil of between 4.0 and 5.5 pH. Most of Iowa’s soils are alkaline, so you’ll need to acidify with a 50-50 mix of native soil and acid peat moss–dampened a bit first. Add a small amount of soil sulfur—available at garden stores or online—enough to raise the pH.  Do not be tempted to hurry the process with aluminum sulfate because it can burn the shallow roots. Prepare soil the previous year. If in doubt, have your soil tested.

    Third, provide moist but well-drained conditions. Blueberries will rot in constantly wet soil and languish in dry or heavy soil. They like sandy, peaty soil (not all-peat!). Ensure a cool root-run with adequate mulch, as blueberry roots are very close to the surface.

    You can purchase blueberries bare-root or in containers. Either way, plant in spring—and nowhere close to a black walnut tree. Dig a wide, shallow hole and amend the soil then set them in. Water well and apply several inches of loose mulch.

    To ensure good fruiting, plant two or more cultivars. The first two years, pick the blossoms off in order to channel all the plant’s energy into developing a strong root system. By doing this, you are preparing for the long haul; if blueberries are given the right conditions, they can live many years (as long as a century, according to one source) and increase in beauty and fruit production each year.

    In spring of the second year, fertilize with any azalea or acid-plant fertilizer, e.g. Holly Tone or similar. Avoid depending on liquid “one-application” fertilizers. Provide a loose mulch of about four inches.

    Critter and winter protection

    Unless you want to feed neighborhood birds, cover the bushes with netting once berries start to ripen or the birds will most definitely get the entire crop. You can find the right netting—half-inch or one-inch—at garden centers or online.

    If deer and rabbits are a problem in your area, you’ll need to provide winter fencing or the buds will be stripped from the branches and you’ll have no berries that year. Chicken wire may be too flimsy to deter the deer.

    As for winter protection, not much is needed. Blueberries suitable for Iowa are extremely hardy. However, since blueberry roots are shallow, 2-4” of mulch (straw, pine needles, shredded leaves, shredded bark, etc.) applied after the ground freezes will do the trick. To avoid disease and/or creating a home for mice, keep the mulch away from the base of the canes.

    Specific varieties

    You have your choice of varieties, no matter which kind of bush suits your needs.

    • Highbush: Duke, Patriot, Bluejay, Blueray, Bluecrop, Rubel, and Elliot.
    • Half-High: Polaris, Northblue, Northsky, Northcountry, St. Cloud
    • Low-bush: Brunswick, Burgundy, Little Crisp, Ruby Carpet (Also look for so-called patio varieties.)

    Pruning blueberry bushes

    Continue disbudding the first two years. Expect a decent crop after four years. After several seasons, you’ll need to prune out some of the old wood every year to make room for new canes–or fruiting will diminish. Late February or early March is the ideal time.

    Old wood is easy to identify. It’s light gray or light brown, brittle, and has shaggy bark. Cut a few of those to the ground. (Avoid leaving stubs.) This allows space for young canes to form. Young canes are smooth and supple-looking with plump, red buds at the end. (Never shear bushes unless you’re growing them purely for ornament—because shearing will remove fruiting buds.) After pruning, your bush should have between 10 and 15 canes, a mixture of old and (mostly) new wood. The center of the bush should be open to sunlight.

    Try a few!

    Blueberries are like any plant—and like people—in the right conditions they’ll flourish. Given the right soil and pH, the right moisture, proper pruning and good sunlight—blueberries will repay you in beautiful blossoms, delicious fruit, and gorgeous fall color for a long time. In fact, they might last longer than you! Start preparing the soil now!

  • 7 Nov 2021 1:00 AM | Brenda Peshak

    After you’ve dug your tropical bloomers for winter storage, what’s next? If you supply the right conditions, it’s easy to prepare such topicals as elephant ear, gladiolus, cannas, calla lilies, dahlias, and similar plants so they’re ready for next spring.

    First, after you’ve dug them up, shake off as much dirt as possible but don’t get carried away and bruise or cut the tissues. If you find rotted or broken areas, use a sharp knife to cut down to healthy growth and dust the cut with powdered sulfur to prevent further damage. (Wear gloves when handling sulfur and keep it off clothing or the smell will never come out.) Sulfur is a natural, highly effective plant fungicide available at most garden centers.

    Second, you’ll need a cool, dry location for storage. An unheated or cool basement is ideal, so long as temperature remains above freezing because frozen tissues will turn to mush once temperatures rise again. No sunlight, please because heat could signal plants to grow, which you don’t want in February!

    For storing, any uncovered, ventilated container will work fine: cardboard box, laundry basket, paper bag, or similar. Air must circulate in order to prevent rot. Avoid plastic tubs unless you’ve cut ventilation holes in them. Do not cover containers.

    Next, you’ll need packing material for tucking loosely around the plants. You can use virtually any organic material like shredded newspaper, excelsior, dry peat moss (bagged or baled), pet bedding (wood shavings—but not cedar because of the oil). Some growers favor vermiculite but that’s a bit expensive. The key here is loose, organic, and airy.

    The last consideration is moisture. Stored items can shrivel unless hydrated from time to time. Once a month (or every two weeks, depending on your conditions), uncover the plants and spritz them with a water bottle. Don’t drown them! Spritz the packing material as well. The goal should be some moisture—but not wet. Think of a wrung-out sponge. After the spritzing, cover the plants again and return to storage.

    Re-plant in spring when soil temperature reaches 60 degrees. Don’t jump the gun because cold, damp soil will cause rot. You can start your tropicals in pots inside a few weeks before setting out and they should do just fine.

  • 24 Oct 2021 1:00 AM | Brenda Peshak
    Fall Clean Up Day

    To rake or not to rake?

    Each fall, people ask whether it’s a good idea to rake up the fallen leaves or leave them in place as a “winter blanket” to protect the lawn during the cold months. The answer is: rake up thick layers of leaves and shred small amounts with a mulching mower.

    Lawn grasses in Iowa are cold-weather grasses and they don’t need a “blanket” to keep them warm. In fact, they’ll resent it.

    According to Richard Jauron, retired ISU horticulturalist, “Turfgrass plants utilize light, water and nutrients to manufacture food. In fall, lawn areas beneath large trees are often completely covered with leaves. The leaf debris prevents the turfgrass plants from manufacturing and storing food prior to winter. Additionally, the leaves of some tree species mat down readily and may smother the grass.”

    Moreover, thick layers of leaves under snow can encourage mold, which can kill or seriously weaken the grass.

    What to do with the leaves you rake up? Invest in a leaf shredder! Shredded leaves make some of the best mulch and compost around—and it’s free, right in your yard! Spread the shredded leaves over your planting beds (a couple of inches) and your plants will love you. If you’d rather not bother, you can bag the leaves and put them by the curb for the Compost-It folks.

    Whichever you do, though, chop up the remaining leaves on your lawn. Make sure they’re fine enough to fall through the grass.

  • 14 Jul 2021 1:00 AM | Brenda Peshak

    Purple Coneflower= native

    The Purple Coneflower,  Echinacea purpurea, is a herbaceous perennial, tolerant to many soil types, sun or shade.  It attracts birds and butterflies to the garden, and  is a good fresh cut or dried flower.  Easy to maintain, it blooms from June to August and self seeds in the naturalized garden.

    Facts about Purple Coneflower:

    Scientific Name : Echinacea purpurea
    Variety, cultivar, or trademark name  Purple Coneflower
    Bloom Time? Color?: Purplish pink during June to August
    Type or Average Life Span:  Divide every 4 years
    Height:  2 to 5 feet
    Width/Spread:  1.5 to 2 feet

    Good things to know about Purple Coneflower :

    The Purple Coneflower is an adaptable plant that grows well in full to partial sun, and in dry to medium, well-drained soil.  It is tolerant of poor soil, heat, humidity and drought.  The plants for new flowers after the initial bloom, and self-seed if dried seed heads are not removed.  Native to Eastern North America, they grow in Hardiness Zones 3 to 8.  Great plant for naturalized areas and need very little maintenance.

    Echinacea purpurea facts:

    One of our most popular native wildflowers, purple cornflower thrives in almost any sunny area except for those with wet, poorly drained soils. Its large, pinkish-purple daisy-like flowers open in late summer, providing one of the season’s most beautiful sights.

    Typically 3-5 feet tall, its stems are strong and rough, as are the coarse, hairy leaves. The name “echinacea” comes from the Greek word for hedge hog, echinos, referring to the spiky appearance of the center cone–hence, the name coneflower.

    Coneflower is important food source for Iowa birds and wildlife:

    When the flowers fade and the seed cone dries, the plant is visited by finches and other birds. Deer and rabbits usually leave the plant alone. Seeds dropped in fall usually produce small plants the following spring, which sometimes bloom the first year. Plants are readily available at local nurseries.

    Very easy to grow, coneflower is an excellent pollinator, attracting bees and butterflies. Its only problems are occasional visits from Japanese beetles and infrequent attacks of aster yellows; if a stalk turns black, remove but do not compost.

    Easy to grow!

    Cultivars abound in shades of red, orange, yellow, pink-purple, and even white. In all, purple coneflower should be planted more frequently—for beauty, for wildlife food, and for ease of cultivation. Coneflowers are found throughout Demonstration garden.

  • 10 Jul 2021 1:00 AM | Brenda Peshak

    White Bearded Iris

    Caring for Bearded Iris is a must.

    Bearded Iris are not maintenance free and should be cared for and maintained. Learn about planting and dividing irises HERE.

    What to do after blooming…

    • A week or so after blooming is finished, cut off the bloom stalk as close to the rhizome as possible. If you leave it on, the stalk forms seeds that rob the plant of nutrients needed for next year.

    Do not cut the leaves back after blooming. The plant needs them for photosynthesis for next year’s growth. (You’ll cut the leaves back later on. See below.

    Iris pests, diseases and what to do:


    Iris are prone to rot in damp situations or when animals dig around them or step on the rhizome. (Deer and dogs are notorious for this.) How will you know if the rhizome is rotting?

    1. First, it’s “squishy” like a bad carrot or potato—you can feel it with your finger.
    2. Second, you’ll definitely smell it. However, you can still save it if enough is left!

    Using a spoon, dig out the “mush” until you reach a solid area, dust with sulfur, and leave it a few days to dry in the sun. (Or, you can leave the clump in place and try your surgery without digging the entire clump. It often works!) If the plant is falling over, however, it’s probably a lost cause so discard it—but not in the compost.

    Leaf Spot:

    In wet years, leaves may develop leaf spot. If you see these rusty-looking patches, remove the individual leaf (by pulling sideways, not up!) and put it in the trash—not the compost. If you wish, spray leaves with an antifungal.

    Iris Borer:

    Definitely the most destructive pest is iris borer, and it’s all too prevalent in this area.

    What is it? The larva of a moth that lays its eggs on previous year’s weeds or unpruned iris blades. In spring, the eggs hatch into tiny worms that crawl up the blade and chew their way down the blade and then into the rhizome—where they proceed to feed. By late July-early August, they are fat, pink, two-inch (or thereabouts) worms that continue eating into the heart of the rhizome until they move into the soil. If left unchecked, the life cycle will begin anew when the larva pupates into the moth that will then lay eggs for the next year.

    What are tell-tale signs of iris borer?

    • Edges of the leaves will look ragged, chewed on.
    • Leaves might be turning yellow.
    • Leaves look water-streaked, or soaked, that’s a sure sign.
    • If you dig up the rhizome and cut it open, you’ll find the culprit. Dig it out and dispose of it. If there’s enough of the rhizome left, you can cut out the rot, dust with sulfur and replant.

    How to prevent iris borer?

    First, vigilance. Watch the leaves in spring and early summer. If you see chewing and water streaking, you can kill the small borer by pinching the leaves between thumb and forefinger, especially toward the rhizome. You may not feel anything, but the little worm definitely will.

    Second, divide the bed every three to four years—and check rhizomes carefully before replanting. Crowded iris beds are a sure target for borers.

    Third, sanitation. Keep weeds pulled. After a hard frost, cut foliage down close to the rhizome. That way, you eliminate places where the moth can lay eggs.

    Although bearded iris take a bit more work, well-grown plants will reward your efforts with the enchanting blooms and fragrance for which they’re justly celebrated. Learn more about Bearded Iris Care.

  • 7 Jul 2021 1:00 AM | Brenda Peshak

    Joe Pye Weed

    One of the hardiest and most dramatic of our native fall bloomers, Joe Pye Weed can reach 6’ (often more) in moist soil and part to full sun. Its plumy domes of vanilla-scented, dusky-rose colored flowers are a common roadside sight in late July through early September, when it becomes a magnet for bees and butterflies.

    Facts about Eutrochium purpureum:

    Scientific Name : Eutrochium purpureum
    Former Name: formerly classified and still sold as Eupatorium purpureum
    Bloom Time:
    late summer
    Color: rose-colored blooms
    Type or Average Life Span:  native perennial
    Height:  6′
    Width/Spread:  spreads prolifically in right conditions

    The Legend of Joe Pye Weed :

    According to legend, Joe Pye was an Indian medicine man in New England who cured typhus with E. purpureumEupatorium perfoliatum, boneset, is said to have relieved symptoms of break-bone (dengue) fever. Today, however, its best use is in native or prairie gardens.

    Easy to grow, low maintenance, relatively disease free, and unpalatable to deer, Joe Pye Weed is not for small-space gardens, as it forms a large clump and self-seeds freely. However, in the right spot, a mature planting—or several–is a breathtaking sight. Give this plant room to breathe.

    You will find Joe Pye Weed in the Pollinator Bed at Demonstration Garden.

    Joe Pye Weed likes to stay moist but in full sun. The blooms are good attractor for butterflies. It is most commonly found in moist meadows and marshes in northeastern Iowa. Plants have serrated, lance-shaped leaves, purple spotted stems, and grow up to 6 feet tall.  Dusty rose-colored flowers are produced in dense, flat-topped clusters in late summer.

  • 1 Jul 2021 1:00 AM | Brenda Peshak

    Planting Bearded Iris

    Iris rhizomes should be divided every 3-4 years.

    Bearded iris (“German iris”) is among everyone’s favorite flower for late spring-early summer blossoms. If their growing conditions are met, they’re fairly easy to grow. However, like many garden treasures, they’re not completely maintenance-free.

    Learn How to Plant Bearded Iris

    • Choose a sunny, well-drained site. Irises require 6-8 hours of sun daily. Sandy soil is good because iris cannot flourish in wet, clayey soil. If your soil is not well drained, consider amending with sand or planting in a raised bed. The idea is to keep the rhizome (the fleshy part with roots attached) relatively dry—otherwise it will rot.
    • Planting season is usually mid-July through August. Planting at this time allows time for settling in before winter.
    • Before planting, incorporate a low-nitrogen fertilizer into the soil. (Bulb fertilizer is a good choice.) Check the N-P-K numbers on the label. The first number needs to be lower than the second—e.g., 3-5-3 or similar. Always follow label directions. More is not In fact, “more” - too much may well burn new roots. Fertilize at planting time and the following early spring.
    • Water at planting time then only during very hot, dry periods. Too much moisture will rot bearded irises.
    • Space generously—18” between plants. Irises must have good air circulation to avoid disease, rot, and pests. (Anyway, they soon fill in!) If planting miniatures, 12” spacing is okay. The closer together you plant them, the sooner they will need to be divided. A crowded iris bed is an invitation to weeds, iris borers, and leaf spot.
    • Do not mulch. Although we’re told to mulch our plants, bearded iris is an exception. Too much moisture on the rhizome will certainly lead to rot. Of course, this means watching out for weeds!

    How to lift and divide irises

    • Using a spade, shovel, or digging fork, lift the entire plant up and cut off all but about six inches of the leaves. (If you leave all the foliage, the roots will be stressed trying to maintain the leaves. Plus, the plant could topple during a rain storm, pulling the rhizome and roots out of the ground.)
    • Next, inspect the rhizome. Remove any damaged or decayed areas with a sharp knife or box cutter. If you’re dividing the plant, cut off the old woody section and discard it. It won’t bloom anyway. You can leave the healthy cut rhizome out in the sun to dry for a few hours or up to two weeks, but after that, it’s time to plant! If desired, dust cut ends with sulfur to discourage disease.
    • Since the roots may die anyway, especially if left out of the soil for a period of time, you can cut them back to about six inches. These will help anchor the plant in its new soil. Of course, if you re-plant immediately, no need to trim the roots, but you still need to trim the foliage back to avoid transplant shock.
    • When the divided rhizomes have formed a callous, you can plant them with the top quarter inch or so of the rhizome exposed to the sun. Do not completely bury the rhizome unless the soil is very sandy.

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