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Iowa State University Extension and Outreach in Polk County

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  • 14 Jun 2021 1:00 AM | Brenda Peshak

    Orange Butterfly Weed

    Butterfly weed (Asclepias tuberosa) is a tall, cluster perennial that forms orange clusters June to August. Tolerant of drought and poor soils, its blooms attract pollinators and its leaves attract Monarch butterfly caterpillars.  Resistant to drought and deer foraging behavior, it works well in rocky shallow soil in full sun.

    Facts about Butterfly Weed:

    Scientific Name : Asclepias tuberosa
    Variety, cultivar, or trademark name  Butterfly weed
    Bloom Time? Color?: orange blooms from June to August
    Type or Average Life Span:  herbaceous perennial
    Height:  12 to 30 inches
    Width/Spread:  12 to 18 inches

    Good things to know about Butterfly weed:

    The prolific Butterfly weed thrives in a variety of soil types and under dry or moist soil conditions.  An excellent candidate for naturalized, rain and pollinator gardens, the Butterfly weed attracts butterflies with its nectar, and monarch butterfly larvae with its leaves.  Deer and drought resistant, it is a long blooming perennial for any garden.

    One of nature’s showiest native wildflowers, orange butterfly weed blooms in midsummer with bright orange, yellow, or yellow-orange clusters on stalks 1-3 feet tall. In the wild, butterfly weed can be found in any sunny area, including dry and rocky sites, prairies, slopes, and roadsides—but it’s equally at home in suburban gardens. It can be found in US Hardiness Zones 3 to 9.

    Milkweed is fairly easy to grow from seed or from purchased plants. Choose the planting site carefully because the long taproot makes successful transfer difficult. Full sun is best, and almost any well-drained soil will be fine. Avoid damp or wet areas, which will prove fatal.

    A member of the milkweed family (one name is “orange milkweed”), butterfly weed does not have milky-sapped stems, but does feature the spindle-shaped seed pod and silky seeds associated with other milkweeds.

    Plant Asclepias tuberosa  for the Monarch population:

    Like many native wildflowers, butterfly weed provides more than beauty. While in bloom, it furnishes nectar for bees, butterflies, and hummingbirds. Equally important–its leaves are the preferred food source for monarch larvae and the place where monarchs lay their eggs. For this reason, it is extremely important to avoid insecticides around milkweed because the plant will absorb some of the poisons—and transfer them to the larva or chrysalis. (If you see that something is chewing on the leaves, don’t spray! You’re a successful host to the next generation of monarchs!)

    Milkweed is a xeric (low-water) plant and very tough once established. It resists most diseases—and deer. So for the sake of the monarchs—and for midsummer beauty—plant an orange butterfly weed! It can be found in the pollinators garden at Demonstration Garden.

  • 6 Jun 2021 1:00 AM | Brenda Peshak

    Lamium maculatum 'White Nancy'

    The ‘White Nancy’ Spotted Deadnettle (Lamium maculatum) is an herbaceous perennial ground cover that grows well in average moisture, in part to full shade.  Dislikes high heat and humidity, but can be cut back to encourage new foliage.  Leaves are green with white shading, which forms tiny flowers in the late spring.

    Facts about Spotted Deadnettle:

    Scientific Name : Lamium maculatum
    Cultivar  White Nancy
    Bloom Time? Color?: white blooms, May to July
    Type or Average Life Span:  perennial, ground cover
    Height:  6 to 10 inches
    Width/Spread:  24 to 36 inches

    Good things to know about Spotted Deadnettle:

    The ‘White Nancy’ Spotted Deadnettle is a creeping perennial ground cover.  It prefers well drained soil and can spread up to 3 feet at maturity. It is hardy in US Zones 3 to 8, but prefers less heat and humidity, and can show scorching and die back during the hottest part of summer.  Spotted Deadnettle can be bothered by leaf blight, aphids or slugs, but it is deer and drought resistant, and can be used as a wide spread ground cover.

    You will find ‘White Nancy’ Spotted Deadnettle in the Woodland bed at Demonstration Garden.

    The ‘White Nancy’ Spotted Deadnettle is a creeping perennial ground cover that grows well in shady well drained areas.  It is a spreading perennial that can be used in naturalized areas of your landscape, providing low growing white/green foliage all season, with small white flowers in late spring.

  • 7 May 2021 1:00 AM | Brenda Peshak

    Siberian Iris

    If you like spring color that reminds you of a Monet painting but you don’t want a lot of fuss, give Siberian iris a try. Although they’re not really from Siberia, they’re hardy to Zone 3 and will survive almost anything Iowa can throw at them.

    What are Siberian Irises?

    Siberians are rhizomatous perennials that grow in a clump and produce one or more stalks of beardless blooms in early-mid spring. Bloom stalks reach to 3 feet above narrow, grass-like green or green-blue foliage that grows around 2 feet tall. Even after blooms are gone, the vase-shaped clumps sway in the breeze, offering visual interest all season.

    Each flower stem bears two to five blossoms in shades of blue, purple, lavender, white, yellow, pink, wine, and bi-colors. The original Siberians were mostly purple, but modern hybridizers have expanded to palette to virtually every color except true red.
    Siberians grow from underground creeping rhizomes that will spread to form impressive clumps that can remain undisturbed for several years until they show signs of crowding.

    Siberian Iris Culture: How to Grow

    Unlike their glamorous cousins, the bearded iris, Siberians are easy to grow if given 6-8 hours sunlight and humus-enriched soil that remains moderately moist. While they will grow near water, they won’t survive if roots are submerged. Whether you’re starting a new bed or re-making an old one, it’s best to loosen the soil 6-8 inches down. Siberians grow best in slightly acid soil (pH 5.5 to 6.9); since Iowa soils are alkaline, it’s best to incorporate peat moss, compost, or some sort of
    humus to lower the pH. (If in doubt, have your soil tested.)

    At planting time, you can incorporate a bit of soil sulfur. Best time to start Siberians is early spring or mid-summer. If you’ve received bare-root plants in the mail, soak the rhizomes in water overnight. Next day, plant the rhizomes 1-2 inches deep, mulch, and keep watered for the remainder of the season. In subsequent years, keep the soil moist but not saturated.

    A top dressing of organic mulch (shredded bark, pine needles, etc.) will do the trick. Do not fertilize the first year. In subsequent years, you can use an acid fertilizer as for azaleas. Provide winter mulch. If the plants have bloomed, remove bloom stalks after
    flowering in order to direct all the plant’s energy toward next year’s growth. If you are remaking an old bed, dig up the rhizomes, divide as needed, discarding old or diseased rhizomes (see below), then plant as outlined above.

    Pests and Diseases

    Siberians are remarkably free from disease. Aside from dry soil, Siberian iris’s worst pest is iris borer. While some believe iris borer does not attack Siberians—they’re wrong. If you see that plants are deteriorating or have stopped blooming, dig up and
    inspect the crown of the plant (where roots meet foliage). If you see a fat, pink worm, remove it, cut away any rot, and replant immediately. To discourage future attacks, keep the area clean of weeds and other debris, avoid overcrowding, and keep the area

    Modern Siberians are hybridized from species hailing from eastern Europe, north eastern Turkey and Russia, and the Caucuses—with others from Japan and Korea. With a background like this, you know they’re tough! Just give them sun, moderately acid soil, enough moisture—and they’ll reward you with lovely blooms every year.

  • 30 Mar 2021 1:00 AM | Brenda Peshak

    Queen of the Prairie | Demonstration Garden

    The Demonstration Garden features a number of Iowa native plants. Natives are plants that occur naturally within a given area. Some have been around since the last ice age, so they’ve adapted themselves to Iowa’s harsh and changeable climate. Because they’ve survived so long in the wild, they don’t require coddling—which makes them ideal for low-maintenance home landscapes.

    Why Highlight Native Plants?

    We highlight native flowers for two reasons: Education and Biodiversity

    1. Visitors to the garden don’t know there is such a thing as native plants!
    2. Many experts tell us that native bird species and pollinators (bees, butterflies, and similar) prefer indigenous flowers for their food source. That’s because they evolved along with the native plants and recognize them more readily than hybrids or introductions from other countries. Natives, then, are more beneficial for Iowa’s wildlife.

    Why bring natives into home gardens?

    • If native plants survive Iowa’s extreme winters and summers, they’ll most likely flourish in your garden—given the right conditions.
    • They are of great benefit to the local wildlife population.
    • Many are extremely beautiful. Who can forget a grouping of baby-blue Virginia bluebells—or tawny orange butterfly weed—or, to round out the season, native asters?

    Here are just a few examples of native flowers at Demonstration Garden

    The shady Woodland Garden contains: wild columbine, queen of the prairie, jack in the pulpit, lady fern, dutchman’s breeches, and blue wild phlox, among others. Look for their blooms in early spring.

    In the sunny Pollinator Garden, you can find liatris (gayfeather), Joe Pye weed, orange butterfly weed, purple coneflower, brown-eyed susan, and purple aster. Most of these are summer or late summer bloomers.

    The Native Grasses garden features native grasses like big bluestem, little bluestem, and prairie dropseed. These need full sun and are at their best in the late summer and fall.

    You can add just about any of these to your home garden. Given the right conditions, they’ll flourish—because they’re tough and used to our climate. About the only thing we shouldn’t do with natives is dig them up from the wild. Let’s preserve our heritage for future generations and leave the natives in place. Once they’re gone, it’s very hard for them to re-establish. They can be purchased from many online catalogs and websites.

    Visit the Demonstration Garden this year and learn more about native species.

  • 25 Mar 2021 1:00 AM | Brenda Peshak

    Virginia Bluebell | Demonstration Garden

    Virginia Bluebell (Mertensia virginica) is an herbaceous perennial that forms stalks of blue flowers from March to April.  It grows in moderate moisture and shade, and grows well in woodland gardens.

    Facts about Virginia Bluebell:

    Scientific Name : Mertensia virginica
    Variety, cultivar, or trademark name  Virginia Bluebells
    Bloom time?  Color?  blue flowers, March to April
    Type or Average Life Span:  herbaceous perennial
    Height:  18″
    Width/Spread:  1 to 1.5 feet

    Good things to know about Virginia Bluebell :

    Virginia Bluebells are native to North America, growing in U.S. Zones 3 to 8. It prefers moist woodlands, forming a clump growing 1 to 2 feet tall, with stalks of blue, trumpet-shaped flowers with foliage dying back to the ground by mid-summer.

    You know it’s spring when the oval leaves of Virginia Bluebells begin to emerge (March to April, depending on the year). Shortly after, baby-pink flower buds appear then open into nodding, trumpet-shaped flowers of medium blue or lavender-blue.


    Native to most of the eastern U.S., Mertensia grows to 18” tall, prefers rich, moist soil in partial shade, and is reliably perennial. If seeds are allowed to fall, the plant spreads into sizable clumps that offer a colorful sight after the dreary winter months. Mertensia is very easy to grow, has no serious insect or disease problems; it resists deer and rabbits, and it tolerates black walnut. Hardy in zones 3-8

    Since the plant goes dormant around midsummer and leaves begin to die back, Virginia Bluebells will need to be intermixed with ferns, hostas, or other plants that prefer similar conditions.

    If you’re a fan of native plants, love pink and blue, and have a semi-shaded, moist area, Virginia Bluebells should be on your list. When winter snows are gone, delicately swaying Virginia Bluebells are a charming addition to the springtime garden.  They thrive in the moist partial shade of a woodland garden, and are hardy during cool spring nights.

  • 15 Mar 2021 1:00 AM | Brenda Peshak

    Dutchmans Breeches

    Dutchman’s Breeches (Dicentra cucullaria) are an early blooming spring perennial that flourishes on the forest floor throughout the United States. Its white to pink blooms appear in March, and are little puffed flowers that hang from a stalk emerging from a low, tight clump of gray-green leaves. Dicentra cucullaria is a native woodland flower hardy in US zones 3 to 7.

    Facts about Dutchman’s Breeches:

    Scientific Name : Dicentra cucullaria
    Variety, cultivar, or trademark name  Dutchman’s Breeches
    Bloom Time? Color?:  March blooming with white, yellow tipped flowers
    Type or Average Life Span:  spring perennial
    Height:  0.5 to 1 foot
    Width/Spread:  0.5 to 1 foot

    Dutchman’s Breeches Symbiotic relationships:

    One of the most unusual and charming native woodland flowers, Dutchman’s breeches blooms in very early spring, lives aboveground for a few weeks then disappears until the following year. Underground portions live on, of course, storing the carbohydrates manufactured by the leaves during the brief period before the trees leaf out and block the sun from the forest floor.

    Why the common name of Dutchman’s breeches?

    When the fragrant flowers open, they resemble a clothesline strung with several pairs of white pantaloons, a garment worn in Holland many years ago. Flowers dangle over ten-inch, fernlike foliage that is attractive in itself.

    Besides being beautiful, however, Dutchman’s breeches benefits early-flying bumblebees on the lookout for nectar. The queen bumblebee, the only one to survive the winter, visits the flower, sips the nectar, and collects pollen—then returns to her nest to lay eggs. In this way, bee and flower benefit one another. Indeed, the two species co-evolved to satisfy each other’s needs—an early source of food for the bee and a means of pollination for the flower.

    Seed Dispersal:

    Dutchman’s breeches has an unusual method of seed dispersal. When the seeds fall to the ground, ants remove them to their nest. Attached to each seed is a fleshy appendage called an elaiosome, which is oily and nutrient-rich. Once the ants consume the elaiosome they remove the seed to their refuse piles—where the seeds proceed to develop for the next year. Having the seeds dispersed at some distance from the parent plant is a means of ensuring continuation of the species should anything destroy the original planting.

    Good things to know about Dicentra cucullaria:

    Although Dutchman’s breeches is truly enchanting, there are a few caveats to be aware of.

    1. Plant will survive only if given moist, shaded or semi-shaded conditions that mimic the forest floor. In this favorable environment, it can spread by seeds or underground tubers to cover a considerable area, so allow plenty of space–or plan to divide as needed.
    2. Wear gloves when handling it, as the plant causes minor skin irritation when touched; this lasts only for a few minutes, but people with sensitive skin should beware. If ingested—not recommended!—people (and livestock) have experienced trembling, staggering, vomiting, diarrhea, convulsions, labored breathing—or some combination. However, it is toxic only in large quantities.
    3. A final caveat: once the plant dies back, it leaves a bare space that needs to be covered with something else, so plan accordingly.

    If Dutchman’s breeches reminds you of bleeding heart, it’s because they’re both Dicentra; foliage is similar and flowers recall one another. But whereas bleeding heart usually retains its foliage throughout the season, dutchman’s breeches dies back not long after setting seeds. Both are lovely spring bloomers that tell us winter is over!

  • 7 Mar 2021 12:00 AM | Brenda Peshak
    Spring Pruning

    Spring has sprung. The best time for pruning is early spring- late February and early March. If you are going to prune this spring do it quickly before the trees and shrubs leave dormancy behind and begin active growth. This is the time when wounds heal more readily and flower buds can be easily seen.

    Proper pruning can maintain plant health. The following are good reasons to prune trees and shrubs:

    1. To eliminate branches that cross- tree limbs will grow into one another. Therefore, we should remove unwanted branches that are on course to cross one other or are already crossing.
    2. To eliminate dead or diseased branches.
    3. To control and shape growth. Needs PruningThis white mulberry is an example of what happens when crossing branches are not removed. The narrow crotch makes it difficult to prune with three cut method.

    You should never remove more than 20% off a healthy middle aged tree- much less for young trees. Young trees should be pruned sparingly and only with the intention of training. A single leader should be determined early to avoid too much thick growth on top which can lead to breakage in storms and heavy winds.

    Proper cuts:

    Pruning causes a tree wound. Therefore make the cleanest, smallest possible cut. Use a three cut method to avoid further injury to plant tissue. First, a cut is made under the branch only half way through several inches out from the collar. The second cut is made just outside of that in the opposite direction. This removes the weight so that you can make a clean cut at the branch collar for the third cut.

    The wound doesn’t actually heal, rather it is callused. This is also called the woundwood. This tissue forms a donut when made properly. When not made properly it is uneven due to being cut too closely to the trunk.

    Wound dressings were once applied regularly but no real evidence suggests it is necessary.

    Exceptions to early spring pruning.

    For spring flowering shrubs, spring pruning will remove flowers so the option is sacrifice, or preferably shape immediately after bloom. For example, trim your lilacs after they finish blooming.

    Only prune Oaks late fall or winter: Many trees are fine to trim any time of the year.  But oaks are an exception. Never prune oaks in the spring, summer, or early fall as this makes them prone to Oak Wilt. Oak wilt is caused by the fungus Bretziella fagacearum (previously Ceratocystis fagacearum). The wounds also make them vulnerable to pests. Therefore, only prune oak trees when they are dormant.

    SAFETY NOTE: Be safe, never prune a branch greater than 2 inches in diameter. Call a professional arborist for larger tree limb removal.

    If you are looking for specific guides, Iowa State extension has a wide range of free PDF’s on pruning that can be found below:

  • 11 Jan 2021 12:00 AM | Brenda Peshak
    When to Order Seeds Order seeds indoors while winter wages outdoors and begin the dreams of springtime!

    While winter rules outdoors begin your plans and dreams of spring indoors.  January winter is more bearable as hours of daylight slowly become longer and spring gardening catalogs arrive in the mailbox.

    When to Order Seeds

    January is the perfect time to order seeds and begin your garden plan for the upcoming season. You will sow seeds outdoors after last frost, or earlier in a green house or indoors with extra lighting. With the large variety of catalogs appearing in the mailbox this month, which should you choose? If gardening is new to you, ask neighbors and friends for recommendations, especially if they are Master Gardeners. I have been ordering from catalogs for over 50 years, so personal experience plays a large part in my decision.

    Factors to consider when ordering and reordering are:

    • number of seeds per packet
    • days to maturity
    • price
    • Do shipments, especially plants, arrive on time and in good order?

    Factors to consider when planning are:

    • soil type
    • sun areas
    • shade areas
    • micro-climates
    • slope
    • heat & cold
    • availability to water, and more.

    For any questions in any of these areas, contact your local county extension office for a huge amount of advice and brochures.

    I have submitted three orders for seeds already and shipments will arrive shortly. Here are a couple pointers for you in selection.

    Let’s take carrots as an example. Some folks like the tried and true varieties such as nantes and danvers. Others prefer newer cultivars such as tender sweet. Packets of mixed colored carrots are also available, but my preference is long and slender cultivars. Since I have heavy clay soil in my ground garden, any kind of carrot is not a good choice. However, in the container gardens, where soil is far more controllable, a foot of loose and friable soil is easier to obtain and maintain. Not surprisingly, carrots do well in containers with enough depth.

    It is easy to get caught up with the plant descriptions and pictures, and thus to over order. With some seeds, spinach, lettuce, radishes and kohlrabe, a second crop can be planted late in the summer for fall harvest.

    Happy ordering!

  • 11 Dec 2020 12:00 AM | Brenda Peshak

    Care of Christmas Cactus

    The Basics About Christmas Cactus

    Care of Christmas Cactus is easy and simple. One of the joys of the holiday season is to experience blooming plants that are available during this time. One of them, Christmas cactus, or slumbergia, is quite carefree and easy to raise. Greenhouses and other retail outlets will have them available around Thanksgiving time; they are available in a number of colors—white, many shades of pink, and red.

    These cacti are succulents, enjoy light and a dry growing environment. After their flowering is complete, let the spent blooms fall off, water sparingly, and do not fertilize. If you need to purchase additional soil, obtain a loose mix oftentimes labeled as “desert mix.” Keep indoors in a well lit area until all danger of frost is behind us.

    Care of Christmas Cactus In the Off Season

    Over the summer months, keep the cacti in a partially shaded area if outdoors, as too much sun will burn them. Water when dry, and about once a month use a slow release fertilizer in the form of granules or small sticks. New growth will be mimimal, as these are slow growers. The longer you can keep them outdoors, the later they will set buds. Minimal light and cool temperatures will also delay bud set.

    In the Fall…

    As cold nights approach, protect them from frost by moving them into a cool area, such as a 3 season porch, or shaded north window. By late in the autumn, you will notice small buds appearing at the leaf tips. Just before you want them to fully bloom, at about December 15 in my case, bring them into full light and warmth, and enjoy the blossoms 7-10 days later.  Continue to water as needed.

    I have never re-potted a Christmas cactus, even though they have been in the same pot for many years. Occasionally, a small branch will fall off, and you can place these into the desert mix to propagate new plants. Have fun, and enjoy the beauty.

  • 26 Oct 2020 1:00 AM | Brenda Peshak
    Prepare Roses for Winter in Iowa

    When to Prepare Roses for Winter in Iowa

    The time to prepare roses for winter is arriving earlier than usual in 2020. It’s best to wait until there has been a hard freeze, meaning temperatures dropping to 28F or below for at least two hours, assuring that the roses are in dormancy. In central Iowa, we usually see our first hard freeze in early to mid November, but forecasters are predicting a hard freeze in the latter part of October this year.

    Winterizing Shrub Roses 

    Shrub roses that are hardy in zone 5 might be fine without any winter protection at all, especially if they are in a sheltered location. However, it’s best to provide several inches of mulch (shredded fall leaves work fine) to protect them from the effects of freezing and thawing. For an extra layer of protection, begin by mounding 6 to 8 inches of soil or compost over the crown, followed by the leaf mulch.

    A collar of chicken wire or something similar may be used to hold the mulch in place throughout the winter months. Fall is not the time to prune your roses, as the moisture in the stems help fortify the plant during the dry winter months. However, lanky roses can be whipped around by winter winds and suffer damage at the base, so trim those back to 24 inches or so if they are in an exposed location. For roses that are hardy in zone 4 or below, no winter protection should be necessary.

    You can read more about the Rose Garden at Demonstration Garden and view our rose gallery.

    Need more information? Visit Iowa State Extension for Publications on Care of Roses -Pruning and Planting, Roses for the Home, and download the  Caring for Roses (Free PDF).

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