Annual and Perennial Flowers PDF

HO-102 Annual and Perennial Flowers By Mary Robson, retired Extension agent, King and Pierce counties, Washington State University. Adapted for Kentucky by Sharon Bale, floriculture extension specialist (ret.) and Richard Durham, consumer horticulture Extension specialist and state Master Gardener...

HO-102 Annual and Perennial Flowers By Mary Robson, retired Extension agent, King and Pierce counties, Washington State University. Adapted for Kentucky by Sharon Bale, floriculture extension specialist (ret.) and Richard Durham, consumer horticulture Extension specialist and state Master Gardener coordinator, University of Kentucky. Many annuals come up on their own from the previous year’s In this chapter: seeds. Some, such as California poppies (Eschscholzia califor- nica) and bachelor’s buttons (Centaurea cyanus), can become Types of Herbaceous Ornamental Plants 01 weedy by reappearing from seed so prolifically. Whether or not this characteristic is desirable depends on your garden’s style. Using Herbaceous Perennials in Garden Design 03 Informally designed cottage-style gardens gain from self-seeded Flower Garden Maintenance 06 plants, but formal gardens, which require precise balance and Bulbs, Corms, Rhizomes, Tubers, and Tuberous Roots 08 layout, do not, and volunteer annuals must be removed. Colorful, long-blooming, and easy to grow, annuals offer Specialized Herbaceous Flower Gardens 09 much to gardens. They often produce flowers or decorative For More Information 10 leaves steadily from early summer until they set seed or are killed by frost. Annuals are particularly useful for colorful win- dow boxes, container plantings, hanging baskets, and school or C an you imagine a world without flowers? Their textures, youth gardens. Their quick growth from seeds or transplants is colors, scents, and forms inspire gardeners, artists, and gratifying for young gardeners. writers. The desire to grow flowers often motivates nov- Some cool-season annuals such as pansies (Viola wittrocki- ices to take up gardening and moves experienced gardeners to ana) and ornamental kale (Brassica spp.) can be planted in become flower specialists. Annuals, biennials, and herbaceous fall to replace summer annuals in containers, window boxes, perennials offer variety and interest to all styles of gardens. and gardens. Table 18.1 lists the height and bloom color of Not so long ago, flowers often were separated from other common annuals. parts of the garden. Masses of colorful annuals filled park and home display beds only in summer. Herbaceous perennials, Biennials laid out in long borders, demanded intense management with- Biennials often confuse gardeners. They require two full out providing year-round interest. Since the 1980s, however, years to complete their growth cycle and die after the second American garden design has moved away from flower displays year. The first year, they grow foliage and roots but do not flower. that are attractive for only a few months, and gardeners now The second year, they flower and go to seed. Their garden uses plan landscapes for all seasons. In today’s smaller gardens, often are closer to those of annuals than perennials, but many are entirely visible from inside the home, combinations of ever- cherished components of perennial gardens. green and deciduous shrubs, conifers, and perennial flowers Some biennials are spectacularly showy because the inflo- keep the scene fascinating year-round. Gardens often include rescence (flower stalk) can be huge, as on the gray-leafed spring-flowering bulbs, containers of annual flowers, herbs for Verbascum olympicum, which reaches eight or nine feet tall. cooking or tea, and grasses for winter texture. Foxgloves (Digitalis purpurea), forget-me-nots (Myosotis syl- Plants in contemporary gardens are selected not only for vatica), and hollyhocks (Alcea rosea) are common biennials. their flowers but for multiseason characteristics, such as leaf Provide undisturbed space for biennial plants, because they form, foliage texture, and color. Flowers remain important, require a summer growing season and winter rest before flow- but the gardening world is taking advantage of new possibili- ering. Many biennials need winter protection in cold climates. ties offered by an enormous range of ornamental herbaceous Some gardeners start biennials in a nursery bed and move plants. These include annuals, biennials, perennials, and bulbs. them to permanent positions in their second year when they are ready to flower. Types of Herbaceous Ornamental Plants Know how to identify the first-year leaves (the vegetative stage) to avoid pulling the plants as weeds before their second- Annuals year flowering period. In some cases, newer cultivars of some biennials have been Annuals live briefly. They germinate, grow, bloom, and go to bred to produce blooms the first season. Hollyhock ‘Queeny seed in one year. Because they die at the end of this cycle, they Purple’ and digitalis ‘Camelot’ are just two examples. When must be replanted the following season. choosing a plant, be sure to read the information about that particular cultivar. CHAPTER 18 Annual and Perennial Flowers Table 18.1. Height and bloom color of common annuals. Plant Height (inches) Bloom color Plant Height (inches) Bloom color African daisy 6–12 White, yellow, salmon Impatiens 8–24 Red, pink, white, Ageratum 4–24 Blue, white orange Amaranthus 48–96 Red, red and green Lantana 12–36 Red, yellow, white, Arctotis 24 White with bluish eye lavender Aster (Callistephus 18 Yellow, pinkish red, Licorice plant 6–10 Grey, lime-green chinensis) blue, white, lavender Lobelia 4–18 Blue, violet, white, Bacopa 6–10 White, blue pink Balsam (Impatiens 12–18 Rose, purple, white Mandevilla Vine Pink balsamina) Marigold (Tagetes) 8 - 48 Yellow, orange to Basil, purple (foliage) 15 Red-purple foliage red-brown Begonia 6–12 Pink, red, white Melampodium 24 Yellow Browallia 8–12 Blue, violet, white Mimulus 12–30 Yellow, red Calendula 12–24 Yellow, gold, orange Nicotiana 24–48 Red, pink, white Cabbage, flowering 8–14 Red to white Nigella 12–15 White, blue, violet Calilbrachoa 6–12 Various Pansy (Viola) 8–12 Blue, purple, white, yellow Castor bean (foliage) 72–96 Red, inconspicuous flowers Petunia 6–12 White to rose, purple Capsicum 6–24 Red, orange, purple Portulaca 8 Yellow, white, rose, fruit orange Cockscomb (Celosia) 18–36 Blue, red, yellow, Salvia 18–36 Blue, red, white orange Salvia farinacea 14–18 Blue, white Cornflower 36 Pink, blue, white (mealycup sage) (Centaurea cyanus) Snapdragon 6–18 Blue, purple, yellow, Coleus (foliage) 8–20 Variegated foliage (Antirrhinum) orange, red Cosmos sulphureus 18–24 Red, orange, yellow Statice, (Limonium) 18–24 Yellow, rose, violet, sinuatum white Cosmos bipinnatus 48+ White, lavender Strawflower 36 White, red, yellow Dusty miller 24 Silvery foliage, yellow (Helichrysum) (Artemisia stelleriana) flowers Sunflower 12–108 Yellow to red-brown Evolvulus ‘Blue Daze’ 6–10 Blue (Helianthus) Fan flower (Scaevola 6–8 Blue, white Sweet alyssum 3–10 White, purple aemula) (Alyssum maritimum) Forget-me-not 12 Blue, pink Sweet potato vine vine Green, purple (Myosotis) Tithonia 48 Orange Four o’clock (Mirabilis) 24 Pink, white, yellow Torenia 12 White, blue, violet Gaillardia pulchella 15–24 Yellow, orange, red Verbena 8–24 White, pink, blue, red Geranium 12–18 pink, red, white, salmon, lavender Vinca 8–12 White, lavender, pink Gomphrena 12–36 Lavender, purple, red, Zinnia 6–36 Red, pink, yellow, white orange, white, lime green Heliotrope 10 Rose Perennials planted them. Some may only live a few years in the garden, if at all. It is very important to choose perennials that are appropriate Unlike annuals and biennials, perennial plants live year after for the location’s hardiness zone and general climate conditions. year. Trees and shrubs are woody perennials. Mature garden, Some hardy perennials may live for several years in this area park, and arboretum landscapes often are composed mostly of and then mysteriously die when no obvious disease or insect woody perennial plants. problem is apparent. This type of death is often attributed to Many familiar garden flowers are perennials, such as peonies the “weather.” When we have wide temperature fluctuations (Paeonia spp.) and Shasta daisies (Leucanthemum maximum). during the winter, the hardiness of the plant may be affected. These plants are called herbaceous because they do not form Tender perennials won’t survive outdoor winter conditions permanent woody branch structures as do shrubs and trees. even with protection. They must be lifted before frost, stored, Hardy perennials live through winter in the ground, reviving and replanted after danger of freezing weather passes. Dahlias, from their crowns in spring. They send up new shoots, often gladiolus, and tuberous begonias are just some examples. through the remains of the previous year’s dead stems, leaves, How a perennial is classified depends on the climate zone and flowers. Some perennials, such as peonies (Paeonia spp.), the plant is being grown in. For example, a lantana is an annual may survive for decades, long outliving the gardener who 18-2  Annual and Perennial Flowers CHAPTER 18 Table 18.2. Bloom season, height, and bloom color of common perennials.* Height Height Botanical name Common name (inches) Color Botanical name Common name (inches) Color Late winter, spring Summer Chionodoxa luciliae glory-of-the-snow 4 blue Achillea millefolium common yarrow 12-18 various Crocus (species and crocus 4 various Asclepias tuberosa butterfly weed 24-36 orange hybrids) Coreopsis grandiflora tickseed 12-24 yellow Endymion hispanicus Spanish bluebell 12-15 blue, Coreopsis verticillata thread leaf coreopsis 18-36 yellow white Echinacea purpurea purple coneflower 24-36 purple, Eranthis hyemalis winter aconite 3 yellow various Galanthus nivalis common snowdrop 6-12 white Echinops ritro globe thistle 12-36 blue Helleborus (species Lenten rose 15-18 various Heliopsis helianthoides sunflower heliopsis 36-48 yellow, and hybrids) orange Hyacinthus orientalis hyacinth 12-14 various Heuchera sanguinea coral bells 12-18 red Iberis sempervirens candytuft 3-6 white Hosta (species, hosta 6-36 purple, Iris danfordiae danford iris 4-6 yellow hybrids) white Leucojum vernum spring snowflake 10-12 white Liatris spicata spike gayfeather 24-36 mauve Mertensia virginica Virginia bluebells 12-14 blue Limonium latifolium sea lavender 24-30 lavender Muscari armeniacum grape hyacinth 6-8 blue Iris kaempferi Japanese iris 34-30 various Narcissus narcissus, daffodil varies various Lilium (species, lily varies various pseudonarcissus hybrids) Scilla siberica Siberian squill 3-6 blue Perovskia atriplicifolia Russian sage 48+ blue Tulipa (species and tulip varies various Phlox paniculata garden phlox 36-48 various hybrids) Rudbeckia fulgida orange coneflower 18-30 yellow Late spring, early summer Late summer and early fall Achillea filipendulina fern-leaf yarrow 24-36 yellow Anemone x hybrida Japanese anemone 24-36 white, Amsonia amsonia 12-36 blue pink tabernaemontana Aster novae-angliae New England aster 48+ violet, Aquilegia (hybrids) columbine varies various purple Aurinia saxatilis basket-of-gold 12 yellow Aster novi-belgii Michaelmas daisy 12-48+ violet Armeria maritima common thrift 6-12 pink Eupatorium purpureum Joe-Pye weed 48+ purple Astilbe arendsii astilbe 24-36 various Sedum spectabile showy stonecrop 12-24 pink Baptisia australis false indigo 36-48 blue Tricyrtis hirta common toad-lily 24-36 lilac Brunnera macrophylla heartleaf brummera 12-18 blue Campanula glomerata clustered bellflower 12-18 blue, purple in Kentucky. In southern Florida, it has become an invasive Convallaria majalis lily of the valley 10-12 white, perennial. When purchasing perennials, look for those plants pink that are hardy in Zone 6 or less. Some parts of Kentucky are Dianthus barbatus sweet William 10-18 various Zone 7, but plants that are labeled as Zone 7b may have some Dianthus cheddar pink 9-12 rose, pink hardiness problems. gratianopolitanus Dicentra spectabilis common bleeding 18-24 pink heart Using Herbaceous Perennials in Garden Design Galium odoratum sweet woodruff 4-9 white Heucherella tiarelloides foamy bells 15-24 pink Because perennials reappear year after year, they have advan- Hemerocallis (hybrids) daylily varies various tages over annuals. The plants can fill space rapidly if grown in Iris (hybrids) tall bearded iris 12-24 various proper conditions. Many reach their mature size several years Iris sibirica Siberian iris 24-36 various after planting, expanding gradually into large, showy clumps. Leucanthemum x shasta daisy 18-24 white There are hundreds of different perennials, each with a distinct superbum texture, color, scent, and form, which makes choosing plants Paeonia suffruticosa tree peony varies various an intriguing adventure. Paeonia (hybrids) peony varies various Most perennials bloom for a fairly short time, from one Papaver orientale Oriental poppy 18-36 various to three weeks, although some, such as coreopsis (Coreopsis Phlox subulata moss phlox 6-9 various verticillata), can bloom persistently for as long as six weeks. *Bloom times are only an estimate, because location and spring temperatures Careful perennial plant selection can provide garden interest can cause plants to bloom earlier or later than expected. from early spring to frost and even through winter. 18-3 CHAPTER 18 Annual and Perennial Flowers Italian arum (Arum italicum) is an example of a plant that Table 18.2 lists perennials by season of bloom and gives produces winter interest. The foliage appears in late fall and their height and bloom color. Figure 18.1 illustrates how plants persists over the winter. The bright orange-red berries that can be arranged according to height, while Figure 18.2 shows are produced on strong stems also provide color well into arrangement by season of bloom. Figure 18.3 is an example of the winter. a garden design that combines perennial and annual flowers Successful flower gardening depends, as does any other with a variety of bloom seasons, colors, heights, and textures. aspect of gardening, on understanding your site’s characteristics and matching them to the needs of individual plants. Annual Selecting Plants and perennial flowers have been hybridized for centuries, Select annual and perennial plants for the best possible chosen from wild plants originating in bogs, sunny prairies, growth qualities. The popularity of flower gardening encour- alpine meadows, woodland shade, and many other growing ages plant hybridizers and growers to offer improved plants conditions. Understand your garden environment before with more vigor, larger flowers, longer bloom periods, and selecting herbaceous plants. Analyze the hours of daylight, soil more attractive leaves. For instance, pansies have been texture, drainage, water availability, and winter frost conditions. selected for color and form, production of pink flowers, Choose plants that have cultural needs matching your garden’s orange/purple combinations (Viola wittrockiana ‘Jolly Joker’), characteristics. and diminutive yellow forms, as well as the familiar, large, For a low-maintenance perennial garden, consider several basic plant characteristics: purple-whiskered faces. When a design specifies a particular plant, look for cultivars Is the plant long-lived (lasting at least four seasons)? that may have improved characteristics over the parent plant. Does it grow strongly but not overwhelm other plants? Often this means seeking a named variety rather than simply Will it have a long bloom time? a straight species. Association garden sales, specialty nurseries, Is it attractive when out of bloom? mail-order catalogs, and knowledgeable local gardeners are Is it generally pest-resistant? good sources for extraordinary plants. Peonies (Paeonia spp.), purple coneflower (Echinacea pur- purea), and Autumn Joy sedum (Sedum spectabile ‘Autumn Joy’) are among the many herbaceous perennials that meet Soil Preparation these criteria. If you follow some sensible basic steps when installing a new Garden design (which should be based on harmonious garden, you’ll have good results. For perennial gardens, soil color patterns), bloom throughout the seasons, and intriguing preparation is a key to strong future growth. Later applications year-round texture depend on the gardener’s taste. Because her- of fertilizer can’t compensate for poorly prepared soil. baceous plants are used intensively in modern gardens, many First, get rid of weeds, especially perennials such as quack- books have excellent suggestions on how to design with them. grass, dandelions, morning glory, and thistles. Then dig thor- Visiting gardens and nurseries and keeping an idea notebook oughly, loosening the soil to at least 12 inches. (Double-digging also will help you develop design confidence and improve your often is recommended for herbaceous perennial gardens. This garden choices. process involves digging 20 to 24 inches deep, loosening the soil, and moving the top layer down about one shovel’s depth. Figure 18.1. Flower border divided into bold plant groupings accord- Figure 18.2. Flower border designed for continuous bloom from ing to height. Background: large groups of tall plants. Foreground: spring through fall. shallower, wider groupings of small plants. 18-4  Annual and Perennial Flowers CHAPTER 18 Shirley poppies (Papaver rhoeas), direct seeding is necessary. When choosing flowers for children’s gardens, seeds such as nasturtiums (Tropaeolum majus) and sunflowers (Helianthus annuus), which sprout quickly and are large enough to handle, inspire satisfaction. Many other annuals and biennials do best if started in a 1. Tulip (P): spring; color varies; 8–24" propagation bed or tray and then transplanted as small plants. 2. Daffodil (P): spring; shades of white or yellow; 8–24" 3. Hyacinth (P): spring; pink, white, purple; 8–12" Marigolds (Tagetes spp.), violas and pansies (Viola spp.), and 4. Pansy (A, late winter planting): winter, spring; blue, snapdragons (Antirrhinum majus) transplant well. Start seed- purple, white, yellow; 8–12"; Ageratum (A, June lings indoors four to six weeks before they will be planted in the planting after pansy is finished): summer; blue, white; 4–24" garden. Provide ample light, using auxiliary light if necessary, to 5. Candytuft (P): spring; white; 12" grow stocky, healthy transplants. Beware of starting seedlings 6. Dwarf marigold (A): summer; yellow, orange to too early; they grow poorly if left too long in low light and red-brown; 8–12" 7. Zinnia (A): summer; red, pink, yellow, orange, crowded indoor conditions. white; 6–36" Buying seedlings from nurseries is very convenient, espe- 8. Dusty miller (P): summer; silvery foliage, yellow flowers; 24" cially for annuals with very fine seeds, notably petunias, 9. Salvia (A): summer; blue, red, white; 18–36" impatiens, and fibrous begonias. Unless you have excellent 10. Cockscomb (A): summer; blue, red, yellow, orange; propagation facilities, plants are difficult to grow from fine seed. 18–36" 11. Larkspur (A): spring, summer; blue, pink, white; 18–36" Perennials 12. Globe amaranth (A): summer; white, pink, purple; Perennials grow more slowly than annuals, and many do 15–30" not bloom the first year, although some will. You can start Figure 18.3. Sample perennial/annual bed with a mix of bloom them from seed in a nursery bed and transplant them to a final seasons, flower colors, and heights. In spring, blocks 1, 2, 3, 4, and 5 will bloom. In summer, blocks 4, 6, 7, 8, 9, 10, 11, and 12 will bloom. location when they are sturdy enough. Often they are ready to A=Annual; P=Perennial. transplant late in their first season. Keep in mind that starting perennials from seed can be This practice increases air and nutrients available to roots and a slow process and may require waiting several years before can produce a fine garden site capable of sustaining plants for any blooms appear. The cost of purchasing perennials is often many years.) directly related to the number of years the plant has been Spread three to four inches of organic material across the in production. While some of the newer cultivars of certain soil surface and dig it in well. This addition will help increase perennials have been bred to produce blooms the first season the soil’s water-holding capacity and improve root penetration from seeding, others require several years of growth before any and aeration. Commercial compost, homemade compost, blooms will be produced. chopped or composted leaves, composted sawdust, fine bark, Division—As herbaceous perennials develop established and composted manure make good amendments. root systems, they spread into large clumps, so many can be Recognize that many perennials form large, heavy root struc- propagated by division. tures, which can rot if the site isn’t well-drained, particularly if Divide perennials as part of your general garden mainte- there is a high water table in winter. If you face this situation, nance, because growth and performance decrease when plants improve drainage or choose plants suitable for damp conditions get crowded. Centers die out on many plants, such as Siberian (for instance, cardinal flower [Lobelia cardinalis]). iris (Iris siberica). Division rejuvenates plants and results in extra Soil testing is helpful when starting a garden on an unfamiliar plants to share with friends or donate to plant sales. site or when expanding an existing garden. Many herbaceous The proper time to divide perennials depends on the par- perennials grow well in slightly acid soil, but some need supple- ticular plant. In general divide fall-blooming plants such as aster mental lime if the soil pH is below 6.0. A soil test will provide a (Aster spp.) in very early spring. Spring bloomers such as iris recommendation for adjusting the pH if it is required. Generally, (Iris spp.) can be divided in late summer or early fall. sulphur can be added to lower the pH and lime can be added Select vigorous shoots from the outer part of a clump. to increase the pH. Discard the center. Divide the plant into several sections of three to five shoots each. Make large divisions, because small pieces will not bloom much the first year after planting. Before Propagation replanting, add compost or other organic materials to the soil. Annuals and biennials Cuttings—Many plants can be propagated from either tip or These flowers generally are started from seed or are pur- root cuttings. Generally, tip cuttings are easier to grow than chased as small plants. Many annual seeds can be sown directly root cuttings. in the garden. For annuals that are hard to transplant, such as 18-5 CHAPTER 18 Annual and Perennial Flowers Take two- to six-inch-long tip cuttings from perennials such Weeding as candytuft (Iberis sempervirens) or lavender (Lavandula angustifolia and others). Remove all foliage from the lower Keep annuals and perennials free of weeds. A combination one-third of the cutting. Insert cuttings in a clean planting mix of hand weeding and mulch is effective. Weed regularly to such as one-half sharp sand and one-half peat moss. prevent seeds from becoming established. Herbaceous plants Professional growers supply bottom heat and provide shade out some weeds when mature but require extra vigilance moisture through automatic misting systems that keep cut- while they are too small to compete. tings moist while roots form. If you don’t have these systems, Use herbicides with great care in herbaceous plantings, if rooting will be slower and require more care, but you still can at all. Always read the label of any herbicide before using. The be successful. Cover cuttings with a sheet of clear plastic to label will list plants that will not be damaged as well as list retain moisture. Support the plastic to keep it from touching those plants that may be severely damaged by that particular the foliage. Place the cuttings in a light area but out of direct chemical. Use them only around woody plants established in sun. In direct sun, high temperatures can build up under the the landscape for more than six months. plastic on warm days and can kill cuttings. It’s best to remove annual weeds at the seedling stage by When cuttings resist a slight tug, they have begun to root. hoeing lightly, avoiding the roots of desired plants. You can The plants then start to take up water and nutrients. Poke holes spot-treat persistent perennial weeds such as morningglory in the plastic to provide more air circulation to the rooting with a postemergent herbicide such as glyphosate (sold as plants, gradually adding holes as more roots grow. When the Roundup and many other trade names), but take great care to plants have formed good root balls, transplant them to a nursery keep herbicides off the leaves of all desirable plants. bed or container and begin fertilizing. Root cuttings also work to propagate some plants, such as Watering Oriental poppies (Papaver orientalis), phlox (Phlox panicu- Most annuals need regular water because they don’t make lata), and baby’s breath (Gypsophila paniculata). Dig plants in deep root systems. However, some annuals, such as cosmos late summer after they have bloomed and are going dormant. (Cosmos bipinnatus), tolerate summer dry spells. Choose pencil-sized roots and cut them into four-inch sections. Do not allow herbaceous perennials to dry out in their first Shoots will not appear until the following growing season. season. Many tolerate dry soils once established, however. Interest in water conservation causes many gardeners to choose Flower Garden Maintenance plants that need little supplemental water. Plants such as arte- misia, echinacea, Jerusalem sage (Phlomis spp.), and santolina Regular, planned maintenance keeps plants healthy and a use only moderate amounts of water. garden looking attractive. To use water efficiently, group plants according to water needs. Till the soil deeply and amend it with compost or other Fertilizing organic material. When you water, use efficient methods such as soaker hoses Annuals need regular fertilizing. Well-prepared soil and or drip irrigation systems, and apply water slowly and deeply. organic mulch help make nutrients available to plants, but annu- als grow so rapidly that supplemental fertilizer helps. When planting, incorporate about five pounds per 100 square feet of Mulching 5–10–5 or 5–10–10 fertilizer. Then fertilize at regular intervals, Organic mulch is useful in perennial and annual flower beds. about every three weeks. Don’t add fertilizer to dry soil; be sure Use compost (commercial or homemade), composted sawdust, to water before and after fertilizing. chopped or composted leaves, or other materials for mulching. When planting a new perennial garden, add about five pounds Two applications of mulch each year are helpful. Apply two of 5–10–5 or 5–10–10 per 100 square feet and dig it in thoroughly to three inches in spring after weeding and fertilizing to retain before planting. Fertilize established herbaceous perennials as soil moisture, suppress annual weed seeds, and improve the they start growth each year. Perennial plants that bloom in late bed’s appearance. Apply mulch again in late fall. As it breaks summer or fall, such as asters, need regular fertilization before down over winter, this material will provide some winter pro- bloom, so feed them monthly until September. Perennials such tection and weed suppression. as peonies that complete their bloom and growth by June do not Do not cover a perennial plant’s crown (the central grow- need fertilizer in midsummer. In general, two light applications ing area above the roots) with winter mulch, but do bring it up of fertilizer per year are sufficient for supplying extra nutrients if to the edge of the crown. In cold locations, you can cover the soil conditions are good. Always water after applying fertilizer. entire plant after the soil freezes or after several freezing nights. If you cover plants too soon, they may begin to grow under the mulch and may be killed by severe cold. Evergreen boughs make a good mulch, particularly in cold winter areas. 18-6  Annual and Perennial Flowers CHAPTER 18 Pull mulch off plants in early spring when weather warms, Fall Cleanup allowing new growth to emerge. Late fall maintenance generally includes cutting back dead stems of herbaceous perennials and pulling out annuals after Staking they are killed by frost. Some gardeners leave seed heads for Many tall herbaceous flowering plants must be tied to stakes birds. Goldfinches love cosmos seeds, and chickadees eat or provided with another support system, especially in windy sunflower seeds right off the plants if squirrels don’t get them and exposed areas. Dahlias, for example, may require support. first. The seeds of many perennials, such as purple coneflower Wind, rain, or the weight of foliage and blossoms will bend or (Echinacea purpurea), attract birds in late summer and fall. break these plants’ stems and ruin the display. Broken stems also can lead to disease problems. Pest Management Many short perennials such as peonies require support to keep flower heads upright. A plant that flops over onto All flower gardens eventually have some pests or diseases. adjoining plants will smother its neighbors and destroy a Learn to use the principles of integrated pest management and garden’s attractiveness. concentrate on growing healthy plants. Strong plants resist Commercial systems such as grates with legs work fine, but disease and insect problems better than weak ones. To reduce you also can improvise supports from bamboo stakes, twigs, disease infestations and cut down on hiding places for insects and or branches. Choose staking material that is about six inches other pests such as slugs, space plants properly to allow good air shorter than the plants’ ultimate height. circulation, clean up litter and dead leaves, and control weeds. Whatever method you use, put support systems in place Several diseases commonly affect annuals, bulbs, and her- while plants are small and tie plants loosely to the stake as they baceous perennials. Powdery mildew (a fungus) attacks peo- grow (Figure 18.4). Rapid growth will hide the stake, wires, nies, zinnias, roses, pansies, and many other flowering plants, or strings. producing a gray, fuzzy coating on leaves and blossoms. Tulips, lilies, and peonies contract botrytis, which affects buds and stems and destroys flowering. Pruning out diseased plant parts Deadheading and Disbudding can help control this disease. Regular maintenance for annuals includes removing flowers Whenever possible, choose disease-resistant cultivars. before they go to seed. This process is called deadheading. By Check with nurseries for new cultivars of phlox and bee balm preventing seed formation, you can extend the bloom period (Monarda) with powdery mildew resistance. on many plants, such as pansies, marigolds, and petunias. Some insects damage a wide variety of plants. For example, Deadheading not only might prolong the bloom period, but it aphids suck juices from many flowering plants. Learn the life improves a garden’s appearance. Some early summer-blooming cycles of garden pests so that you can protect beneficial preda- perennials such as certain daylilies (Hemerocallis spp.) produce a tors and minimize use of broad-spectrum insecticides. Aphids, second flush of flowers in fall if stems are cut to the ground after for example, have many natural enemies, including lady beetles, bloom and before seeds set. In other cases, however, seeds may lacewings, wasps, and birds. be part of the garden show. Gladwin iris (Iris foetidissima), for Slugs and snails attack tender shoots of bulbs, lilies, and example, is grown for its showy seed pods. young transplants and are often a problem where hostas Plants such as dahlias produce larger flowers if disbudded. are planted. Hand picking and selective use of baits can A stalk may have five or six buds; to disbud, snap off all but one help you manage slugs. Place baits in traps rather than on each stem. broadcasting them. (a) (b) (c) (d) Figure 18.4. Staking plants: In (a) and (b), plants are tied too tightly. In (c) and (d), principal branches are tied loosely, which is better. 18-7 CHAPTER 18 Annual and Perennial Flowers Consult relevant publications and experts for specific Tuberous roots are composed of root tissue. Dahlias and controls. Make sure you have properly identified the problem tuberous begonias are examples of plants with tuberous roots. before applying any control. Rhizomes are specialized stems that grow horizontally at or just below the soil surface. German iris, lily-of-the-valley, and bamboo have rhizomes. Bulbs, Corms, Rhizomes, Tubers, Gardeners often lump these different botanical structures under and Tuberous Roots one heading, calling them all “bulbs.” This loose classification works for general purposes, but the distinctions between the types make Many garden plants are classified botanically as bulbs, a difference in how each is propagated and stored. corms, rhizomes, tubers, or tuberous roots. All of these have Like other herbaceous ornamentals, bulbs, corms, and tubers underground organs that store food for the plant. Many, such as are classified as hardy or tender. Most hardy bulbs and corms hyacinths, tulips, and crocuses, can survive for a time without are planted in fall for early spring bloom. Crocuses, narcissus, soil around their roots, which enables them to be stored and tulips, hyacinths, and grape hyacinths define spring for many shipped easily. Figure 18.5 illustrates flowers of several types people. Lilies, which bloom in early or midsummer, may be of bulbs and corms. planted in fall or early spring. Bulbs are composed of a thin, flattened stem surrounded by Tender bulbs, tubers, and corms generally bloom in mid-to-late fleshy, dried leaf bases called scales. Roots grow from a basal summer. Examples are dahlias, tuberous begonias, and gladiolus. plate. Onions, garlic, narcissus, tulips, and lilies are examples of Plant them when the ground warms after the last frost. To keep plants that form bulbs. Slicing an onion vertically and observing these plants for more than one season, dig them up in the fall and the interior gives a good look at a bulb’s anatomy. store them in a frost-free location. Corms have solid interiors, developed from swollen stems. If you cut one, you see a homogenous mass inside. Roots form at the base. Some examples of plants that form corms are crocus, Selection and Storage watsonia, and gladiolus. Choose solid, healthy plants. With lilies, tulips, and narcissus, Tubers are swollen, modified, underground stems. They larger bulbs yield larger blossoms. Some bargain bulbs are not don’t have basal plates where the roots originate. Tubers come worth the price, no matter how inexpensive, because they are in various shapes and include caladium. too small to bloom well. Galanthus (Snowdrop) Eranthis (Winter aconite) Anemone blanda Allium Iris reticulata giganteum 36 Crocus Fritillaria Grape hyacinth imperialis Hyacinth 30 Tulip (early) Daffodils Height (inches) Tulips 24 (midseason) Tulip (late) 18 12 6 5” 8” Planting depth very early spring early spring mid-spring late spring Bloom time Figure 18.5. Bulbs and corms offer a variety of blossoms. 18-8  Annual and Perennial Flowers CHAPTER 18 Purchase hardy bulbs in the fall. Don’t leave bulbs in a hot car trunk while shopping; the plants may be damaged or killed. Specialized Herbaceous Flower Gardens If you can’t plant bulbs immediately, keep them cool and dry. Specialized herbaceous flower gardens include container Temperatures below 65°F are best for storage. Use paper sacks plantings, bog gardens, and water gardens. rather than plastic bags, since mold may develop if moisture accumulates inside the package. Container Plantings After digging plants such as dahlias and cannas in the fall, Almost all gardeners have some form of container plantings, store them in slightly damp peat or perlite. Do not let them often in addition to other types of gardens. Containers allow completely dry out; check them regularly and dampen them even those with limited space such as a rooftop, balcony, or if necessary. front stoop to have vigorous gardens. The potting material contributes vitally to the success of Site Preparation and Planting container plants. Plant roots must get sufficient air. If the soil is Drainage is vital for most bulbs, corms, tubers, rhizomes, too dense, it packs down, contributing to root rot or other dif- and tuberous roots. With a few exceptions, such as Japanese ficulties. Be sure to use a potting material that contains sufficient iris (Iris ensata), they rot in wet soil. Snowdrops (Galanthus gritty particles in the form of pumice, perlite, or vermiculite. nivalis), crocuses, narcissus, tulips, and lilies must have excel- Garden soil doesn’t work well in containers because watering lent drainage. If your garden site drains poorly, place bulbs in packs it and reduces available oxygen. containers or raised beds. Choose a container suited to the plant’s eventual size, and Dig the soil as for annual or perennial flowers and add be sure it has sufficient drainage holes in the bottom. Scrub organic amendments such as compost. Remove all perennial pots well. Do not add a layer of gravel or other material to the weeds before planting, and watch for emerging annual weed bottom of the pot; this practice actually reduces drainage. Fill seedlings after planting. the clean pot full of potting soil. When planting, excavate the planting area, place fertilizer You can reuse potting mixes year after year unless the plants below the root level, and mix it thoroughly with soil. Slow- in them were seriously diseased. Before replanting, dump the release fertilizers or general 5–10–10 formulations work well mix out of the pot, aerate it, and add new grit if necessary. for fall-planted bulbs. Do not place bulbs directly on fertilizer. Annuals grown in containers will require more frequent Don’t plant bulbs and tubers in dry soil; roots cannot begin fertilization. Regular watering will leach the initially applied to grow without moisture. If the soil is very dry during fall nutrients from the soil. Follow the package directions for slow- planting, dig a hole for the bulbs, fill it with water, and allow it release fertilizers. An additional application may be necessary to drain before planting. midway through the growing season. If water-soluble fertilizers Planting depth depends on soil conditions. Kentucky are being applied, follow the label recommendations for how Extension publications or local nurseries can give you specific frequently this should be applied. Remember, plants grown in suggestions. Many growers suggest planting about three times containers will require regular watering. When watering plants, the depth of the bulb. be sure to water thoroughly and then allow the plants to dry Shallow-planted bulbs may frost-heave and are easily dug out out before watering again. Smaller containers such as hanging by rodents, which munch on them. To prevent rodent damage, baskets may require watering twice a day to maintain vigor dur- plant them in a hardware cloth “cage.” ing the heat of the summer. Generally, the larger the container, Mulch hardy bulb and corm plantings lightly with two to four the less frequently it will need to be watered. inches of composted leaves, shredded fir bark, or composted sawdust. Keep mulches open and light enough to allow shoots Bog and Water Gardens to emerge in spring. Small fountains, pools, and other water features are increas- ingly popular in gardens. Many herbaceous perennials adapt Watering and Fertilizing well to water gardening. A pool can be surrounded with After planting, be sure to water the planting bed thoroughly Japanese iris (Iris ensata), ligularia (Ligularia dentata), rodgersia and continue to water during periods of dry weather in the fall. (Rodgersia podophylla), and adapted native plants. A barrel Fall-planted bulbs begin to produce a root system, and lack of with a fountain bubbler can hold water lilies, many of which water may severely damage the bulbs. are winter-hardy, even in cold climates. Fertilize spring bloomers when they are about an inch tall, Some gardeners place a simple, shallow bowl of water in the using a 5–10–10 granular formula or a liquid fertilizer. In dry garden to reflect the sky. Water features also attract wildlife, areas, water spring-blooming bulbs after flowering ends. Let especially birds. the leaves wither naturally and don’t pull them out until they are brown. Move spring-blooming bulbs and corms only after all foliage has ripened (usually in late summer). 18-9 CHAPTER 18 Annual and Perennial Flowers For More Information Harper, P., and F. McGourty. Perennials: How to Select, Grow, and Enjoy (HP Books, Tucson, 1985). UK Extension Publications Hartmann, H.T. Plant Propagation: Principles and Practices, 7th Annual Flowers (HO-65) ed. (Prentice Hall, Englewood Cliffs, NJ, 2001). Perennials for Sunny Locations (HO-76) Hobhouse, P. Color in Your Garden (Little, Brown, and Co., Perennials for Shady Locations (HO-77) New York, 1985). Spring, Summer, and Fall Bulbs (HO-80) Lloyd, C., and G. Rice. Garden Flowers from Seed (Timber Press, Portland, OR, 1994). Books Macunovich, J. Caring for Perennials: What to Do and When to Armitage, A.M., Armitage’s Manual of Annuals, Biennials, and Do It (Storey Publishing, Pownal, VT, 1997). Half-Hardy Perennials (Timber Press, Portland OR, 2001). Phillips, R., and M. Rix. The Random House Book of Perennials, Armitage, A.M., Armitage’s Garden Annuals (Timber Press, 2 vols. (Random House, New York, 1991). Portland OR, 2004). Raven, S. The Cutting Garden: Growing and Arranging Garden Armitage, A.M. Herbaceous Perennial Plants: A Treatise on Flowers (Frances Lincoln, Pleasantville, NY, 2006). Their Identification, Culture, and Garden Attributes, 3rd ed. Rix, M. Growing Bulbs (Timber Press, Portland, OR, 1986). (Stipes Pub Lic., 2008). Thomas, G.S. Perennial Garden Plants or the Modern Bloom, A. Alan Bloom’s Hardy Perennials (Batsford, London, Florilegium, 3rd ed., revised (Sagapress, with Timber Press, 1991). Portland, OR, 1990). Eyewitness Garden Handbooks: Perennials, 1st American ed. Wilson, J.W. Landscaping with Container Plants (Houghton (DK Publishing, New York, 1996). Mifflin, Boston, 1990). Elliott, J. The Smaller Perennials (Timber Press, Portland, OR, 1997). Periodicals Hansen, R., and F. Stahl. Perennials and Their Garden Habitats, Fine Gardening, www.finegardening.com 4th ed. (Timber Press, Portland, OR, 1993). Garden Design, www.gardendesign.com Harper, P. Designing with Perennials (Macmillan, New York, Gardens Illustrated, www.gardensillustrated.com 1990). Horticulture, www.hortmag.com Revised 01-2024