Spring-flowering woodland wildflowers that are attractive additions to shady areas in the home landscape include:
Learn more in this article: Native Woodland Flowers for the Home Garden
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.
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.
While not widely planted in home gardens, hardy geraniums (Geranium spp.) are attractive, easy-to-grow perennials. Numerous species and varieties are available. Plants typically bloom in late spring/early summer. The 1- to 2-inch-diameter flowers may be white, pink, magenta, purple, or blue. Several double flowering varieties are also available. Hardy geraniums commonly grow 6 to 12 inches tall. In fall, the foliage of many varieties turns to shades of yellow, orange, or red. Hardy geraniums prefer moist, well-drained soils and partial to full sun. They have few insect or disease problems.
Hardy geraniums should not be confused with common garden geraniums. Garden geraniums are not “true” geraniums. Garden geraniums are annual plants which belong to the genus Pelargonium.
Tree peonies are small woody shrubs. Unlike herbaceous peonies, the stems of tree peonies do not die back to the ground in fall. Tree peonies can be successfully grown in USDA Hardiness Zones 4 to 8.
Cold winter temperatures can damage young tree peonies (especially those in northern portions of Iowa.) Rabbits can also damage plants in winter. Rabbit damage can be prevented by encircling each plant with chicken wire or hardware cloth in fall. Fill the enclosure with a light, airy material, such as straw or pine needles, to protect young plants from cold winter temperatures.
Protective materials should be in place by mid to late November. Remove the materials in early to mid-April.
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.
The method for determining the area of your lawn or garden depends on the shape. Use the information below to find the area of your garden bed or lawn.
Rectangle | Triangle | Circle | Semicircle | Oval | Irregular-Shaped
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
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
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
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
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
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
Jack-in-the-pulpit (Arisaema triphyllum) seeds can be sown directly outdoors or started indoors. Harvest the cluster of berries as soon as they turn red in late summer. Each berry usually contains 4 to 6 seeds. Remove the seeds by gently squeezing them from the berries. Seeds can be planted immediately outdoors. Plant seeds ½ inch deep in a moist, shaded location.
Jack-in-the-pulpit seeds can also be started indoors. Before sowing the seeds indoors, the seeds must be stratified (exposed to cool, moist conditions) for 60 to 75 days. Jack-in-the-pulpit seeds can be stratified by placing them in moist sphagnum peat moss or sand and then storing them in the refrigerator for 2 to 2½ months. Suitable storage containers include plastic bags and small food storage containers. After the seeds have been stratified, remove the seeds from the sphagnum peat moss or sand. Plant seeds ½ inch deep in a commercial potting mix. In spring, plant the seedlings outdoors.
For most perennials, an application of 1 to 2 pounds of an all-purpose garden fertilizer per 100 square feet is adequate. Excess fertilization produces weak, leggy growth and inhibits flowering. Early spring (late March to mid-April) is the best time to fertilize perennials in Iowa.
Cannas are normally grown from rhizomes. However, it is possible to grow cannas from seeds. Canna seeds have hard seedcoats. Prior to sowing, soak the seeds in water for 24 hours. Sow the seeds in a commercial germination medium, such as Jiffy Mix. After sowing, lightly cover the seeds, then water the medium. Allow the medium to drain for a few minutes. Afterwards, cover the container with clear plastic wrap and place it in a warm location. The temperature of the medium should be maintained at 70 to 75 degrees Fahrenheit. Germination should occur in 7 to 14 days. When the seeds germinate, remove the plastic wrap and place the seedlings in a sunny window or under fluorescent lights. When the canna seedlings are large enough to handle, transplant them into individual containers. Plant the cannas outdoors when the danger of frost is past in spring.
Learn more about cannas in this publication: Cannas for Home Landscapes.
Newly emerged perennial growth is susceptible to damage from freezing temperatures. While freezing temperatures may have damaged or destroyed the new growth, the roots and crowns of healthy, well-established perennials should still be alive. The damaged perennials should send up a second flush of growth in a few weeks. Good care (for example, watering weekly during dry weather) this spring and summer should help the perennials recover.
Bee balms don’t require frequent or heavy fertilizer applications. Sprinkling a small amount of an all-purpose garden fertilizer, such as 10-10-10, around each plant in early spring is usually sufficient. Avoid excessive fertilization. Frequent or heavy applications of fertilizer encourage rampant, succulent growth and may increase the severity of powdery mildew.
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:
Plant heights vary somewhat based on the growing conditions at the site. However, there are several groundcovers that are 12 inches or less in height.
Low-growing groundcovers for shade include:
Excellent low-growing groundcovers for sunny areas contain:
When selecting perennials for the home landscape, it’s important to consider their size, bloom period, hardiness, and cultural requirements. Another consideration is their longevity. Some perennials are short-lived. Short-lived perennials persist for several years and then decline and fade away. In contrast, some perennials are extremely long-lived. It’s not uncommon to see 50- to 60-year-old peonies in the yards of older homes in Iowa.
Long-lived perennials include:
When given favorable growing conditions and good care, long-lived perennials often thrive for 20 or more years.
The brightly colored flowers of moss phlox (Phlox subulata), oftentimes referred to as “creeping phlox,” are a common sight in many home landscapes in spring. Moss phlox forms dense, carpet-like mats. Plants are 4 to 6 inches tall. Its foliage is narrow, stiff, and needle-like in appearance. Flower colors include white, pink, red, blue, and purple. Excellent varieties include ‘Emerald Blue,’ ‘Emerald Pink,’ ‘Scarlet Flame’ (rose-pink), and ‘White Delight.’ Moss phlox is easy to grow. It performs best in sunny areas and well-drained soils. Moss phlox is useful for edging beds and as a groundcover for sunny slopes. It also looks nice planted atop a wall or in rock gardens.
Some perennials emerge early in the spring. In Iowa, it’s common to have relatively warm days in early or mid-March and it is equally common to have below freezing temperatures in April or even early May. In most cases, early leaf growth on bleeding heart, hosta, columbine, catmint, and other perennials will be just fine with cold temperatures. If temperatures are cold enough, especially below 26°F to 28°F, then damage could occur. Freezing temperatures may damage or destroy the newly emerged foliage of perennials, however, their roots and crowns should be unharmed. The damaged perennials should send up a second flush of growth in a few weeks. Good care in spring and summer should help the perennials recover.
A native plant is described as any plant endemic to an area. What is typically up for interpretation (and what makes the discussion of native plants challenging sometimes) are the boundaries of that area.
Often, the area is defined by political boundaries like state lines, but it can also be defined by boundaries created by geographical features (mountain ranges, rivers, oceans, etc), climatic zones (continental, desert, etc.), ecoregions (grasslands, forests, etc.), and/or soil types (sandy, fertile, etc.), among other things.
Another complicating factor is that the native range for any particular plant species changes over time. What is not found in an area today may have been growing there hundreds or thousands of years earlier. Shifting environmental conditions or major events, such as glacier advances, can change the native range.
In the United States, native is typically defined as any organism found in that region before European colonization. The region can be defined by geographic features (east of the Rocky Mountains, east of the Mississippi River, etc.), ecoregions (the Great Plains, the eastern temperate forests, etc.), county or state lines, and/or commonly accepted political regions (the Midwest, New England, etc.).
Each gardener has their own interpretation of an acceptable region or area that they consider "native."
The broadest area considered native for many living in Iowa is defined as areas east of the Rocky Mountains within the United States and Canada. This area is primarily grassland or forest with a continental climate.
The narrowest area considered "native" for those living in Iowa is often defined as a region within the state (i.e., Western Iowa, Central Iowa, Northeast Iowa, etc.), although county is also used as a very specific and small region.
Variety and cultivar are two terms often used interchangeably by gardeners and horticulturists, but they are not the same thing.
Both are part of the scientific name. Both appear after the specific epithet (second term in a scientific name). Both refer to some unique characteristic of a plant. However, this is where many of the similarities end.
Varieties often occur in nature and most varieties are true to type. That means the seedlings grown from a variety will also have the same unique characteristic of the parent plant. For example, there is a white flowering redbud that was found in nature. Its scientific name is Cercis canadensis var. alba. The varietal term "alba" means white. If you were to germinate seed from this variety, most, if not all would also be white flowering.
Cultivars are not necessarily true to type. In fact cultivar means "cultivated variety." Therefore, a cultivar was selected and cultivated by humans. Some cultivars originate as sports or mutations on plants. Other cultivars could be hybrids of two plants. To propagate true-to-type clones, many cultivars must be propagated vegetatively through cuttings, grafting, and even tissue culture. Propagation by seed usually produces something different than the parent plant.
Varieties and cultivars also have differently naming conventions. A variety is always written in lower case and italicized. It also often has the abbreviation "var." for variety preceding it. The first letter of a cultivar is capitalized and the term is never italicized. Cultivars are also surrounded by single quotation marks (never double quotation marks) or preceded by the abbreviation "cv.". For an example of a cultivar of redbud, consider Cercis canadensis 'Forest Pansy' (or Cercis canadensis cv. Forest Pansy) which has attractive dark purple spring foliage and pinkish-purple flowers.
Can a plant have both a variety and a cultivar? Sure. One good example is Sunburst Honeylocust. Its scientific name is Gleditsia triacanthos var. inermis 'Sunburst'. The term "inermis" means without thorns and "Sunburst" refers to the bright golden spring leaf color.
There are many native woodland wildflowers that are great additions to the shade garden. Most are ephemeral with a relatively short (but impactful) bloom time in early spring before the foliage dies back to the ground in early summer. These often small-statured perennials are easily tucked among other shade garden plants and add much needed interest and color in the early spring before dying back to make room for the other plants like hosta or coral bells. Many are available from local or mail-order nurseries. Never dig these plants from their native habitats.
Some great native ephemeral woodland wildflowers include:
Learn more in this article: Native Woodland Flowers for the Home Garden
While most gardeners prefer to grow perennials from established plants in containers or as divisions, transplants, or bare root, it is possible to grow many perennials successfully from seed. The reason why perennials grown from established plants are preferred is because they are often vegetatively propagated by division or other methods making them identical to the parent plant. Perennials grown from seed will be similar to the parent plant but may differ in flower color, leaf pattern, size, or in other ways.
Many perennials have cold treatments or other requirements for successful germination and many will take several years for the plant to become large enough to flower. Research the growing requirements for any perennial to understand what special germination requirements are needed to grow them from seed.
While any perennial could potentially be grown from seed, these perennials are relatively easy because they have simple germination requirements and grow to blooming size quickly.
* a biennial that often behaves as a perennial in the garden
One of the first signs of spring is the emergence of crocuses, daffodils, and other spring-flowering bulbs. Several other perennials also bloom in early spring and complement these familiar bulbs.
Lenten Rose (Helleborus orientalis) is a semi-evergreen to evergreen perennial that is usually one of the first plants to bloom. The nodding, bell-like flowers appear in March and range in color from creamy white, to pink, to burgundy.
Pasque Flower (Pulsatilla vulgaris) is a compact perennial reaching 4-6 inches tall that grows well in full sun to part shade. The pasque flower produces purple, maroon, or white flowers atop finely dissected foliage in the first few weeks of spring.
Heartleaf Brunnera (Brunnera macrophylla) is a low growing, 12- to 18-inch-tall, mounding perennial with attractive heart-shaped leaves mottled with white or silver. In early spring, small, blue flowers appear that resemble the flowers of the classic annual, forget-me-not, giving the plant its other common name – perennial forget-me-not.
A few other early spring bloomers include:
There are many trees, shrubs, perennials, and vines that can be planted in an Iowa landscape. What you decide to plant is based on many different considerations. While selecting plants that are attractive to you is certainly a consideration, matching those plants to the growing conditions is essential to create an attractive and easy-to-care-for landscape.
Factors to consider when selecting plants for your landscape include light, soil conditions, winter hardiness, nativity, pest pressure, size, and ornamental features.
Determine the amount of light your planting location receives. Areas that receive six or more hours of direct sunlight a day are considered full sun. Full shade locations are often described as receiving two hours of direct sunlight or less per day.
Most trees and shrubs grow best in full sun, but there are several that tolerate partial shade locations (those sites that receive 3 to 4 hours of direct sun each day). Perennials are available that grow in nearly any light level from full sun to full shade.
Use these resources to find the best plant for your landscape based on the amount of light the area receives.
The moisture level of the soil is also an important consideration. Plants that perform best in moist to wet soils will require much more irrigation and maintenance. Observe the soil conditions or conduct a soil drainage test to determine the moisture levels of the area and match plants to that location based on their preferred soil conditions (e.g., dry, well-drained, wet).
Soil fertility is also an important consideration. While nearly all plants will appreciate abundant nutrients, some will tolerate low-fertility better than others. For some plants, such as native prairie species, excessive fertility can lead to tall, lanky growth that may be too large for the space or less attractive. Conduct a soil test to determine the quality of the soil and its fertility, and amend the soil or match plants to that location.
Utilize these resources to select the ideal plant for your landscape, taking into account your soil conditions.
Not all plants will survive an Iowa winter. If you want the plant in your garden year after year, those that are winter hardy need to be selected. The USDA Plant Hardiness Zone map divides the country up into several zones based on the average lowest winter temperature. According to the 2023
version of the map, nearly all of Iowa is in Zone 5 (average lowest temperature is between -20 and -10°F), with the northern half in 5a and the southern
half in 5b. Small areas in northeast Iowa are in Zone 4b, and small areas in southeast and southwest Iowa are in Zone 6a.
Use this publication to learn more about landscape plants well-suited for your area based on winter hardiness: Gardening in Iowa Zones (PDF).
Mature size of the plant is an important consideration as plants that are too large for their location require regular maintenance like pruning and may interfere with structures, roadways, or utilities. Always note the mature height and width of your plants and be sure to select plants that will not outgrow their area.
There are a number of species and varieties of bulbs and bulb-like structures like corms and tubers that grow well in Iowa. Some of these species are readily available from retailers and others may have to be purchased from specialty producers or online retailers.
Learn more in this article: Selecting and Planting Spring-Blooming Bulbs
Plant calla lily rhizomes 1 to 2 inches deep in a well-drained potting mix about 6 to 8 weeks before the average last spring frost in your area. After potting, water well and place the containers in a warm, 70 to 75°F location. Keep the potting mix moist, but not wet.
When foliage appears, move the plants to a sunny window or place them under fluorescent lights. Calla lilies should be planted outdoors after the danger of frost is past. Appropriate planting times would be early May in southern Iowa, mid-May in central portions of the state, and late May in northern counties. Before planting outdoors, harden or acclimate the calla lilies to outdoor growing conditions. Initially, place the plants in a shady, protected location and then gradually expose them to longer periods of sunlight. After they’ve been hardened, plant the calla lilies in a moist, well-drained soil in partial shade.
Learn more in this article: Planting and Caring for Tender Perennials.
Start canna rhizomes indoors 4 to 6 weeks before the average last frost date in your area. Plant the cannas in large pots. The rhizomes should be covered with 3 to 4 inches of potting soil.
Learn more in this article: Planting and Caring for Tender Perennials.
The growth rate of the seedlings and the outdoor planting date determine when to sow seeds indoors. The crop time (number of weeks from sowing to planting outdoors) for several popular flowers and vegetables are as follows: 10 to 12 weeks - geranium; 8 to 10 weeks - petunia and impatiens; 6 to 8 weeks - marigold, pepper, and eggplant; 5 to 7 weeks - tomato, cabbage, broccoli, and cauliflower; 3 to 4 weeks - cucumber, watermelon, muskmelon, and squash.
Plant caladiums indoors 4 to 6 weeks before the average last frost in your area. Tubers should be planted 1 to 2 inches deep. When planting tubers, place the knobby side up. The knobs are the tuber’s eyes or buds.
Learn more in this article: Planting and Caring for Tender Perennials.
Early spring is the best time to divide ‘Autumn Joy’ and other upright, clump-forming varieties sedum (Hylotelephium). Dig up plants in early spring just as new growth begins to appear. Divide each clump into sections with a sharp knife. Each division should contain several shoots and a portion of the root system. Replant the divisions immediately. Sedums perform best in well-drained soils in full sun.
Learn more in this article: How to Divide and Transplant Perennials.
