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Bulbs are the epitome of nature's talent for packaging, containing within themselves all of the essentials they need to grow and flower. Some don’t even require soil—just witness a paperwhite narcissus blooming happily indoors in nothing more than a bowl of marble chips. But it is outdoors that bulbs really shine. Most are hardy and undemanding; some will even naturalize and provide color year after year. Whether for borders, cutting gardens, containers, rock gardens or naturalistic plantings, bulbs deserve a place in every garden scheme.
Generally, bulbs are divided into two categories: the spring-flowering types, which are typically planted in the fall; and the summer-flowering bulbs, usually planted in the spring. Lilies (Asiatics, Orientals, tigers) are an exception to this rule; they can be planted in either spring or fall for summer blooms.
Another crucial consideration is whether the bulb is hardy or tender. Hardy bulbs (daffodil, crocus, hyacinth, tulip, lily, etc.) will survive the winter right in the ground to bloom again the following year. Tender bulbs (gladiolus, canna, dahlia, etc.) will also flower year after year, but in cold climates they must be dug up or "lifted" in the fall, stored indoors over the winter, then replanted the following spring.
A naturalized planting is one of the most popular uses for bulbs in the landscape. Instead of planting the bulbs in a formal bed or border, you scatter them in irregular groupings across an area of lawn or meadow, or at a woodland edge. For the most natural effect, try not to plant bulbs in straight lines or discernible patterns.
Naturalizing bulbs in your lawn works well with the smaller, daintier flowers like crocuses, puschkinia, squill (Scilla), grape-hyacinth (Muscari), or snowdrops (Galanthus). These bulbs flower early in the season and their foliage dies back fairly quickly. If you plant such bulbs in a lawn, don't mow until the foliage has yellowed and died back. At this point, the plant will have stored all the food it needs in the underground bulb to produce next year's bloom.
Most bulbs appreciate well-drained soil and sunlight. Keep in mind, however, that bulbs that flower early in the spring will have bloomed and faded long before deciduous shrubs and trees have begun to leaf out. So treat think of spring-blooming bulbs much like spring wildflowers. A fairly open woodland setting or orchard makes an ideal setting, particularly for long-stemmed showy bulbs like daffodils and early tulips, which can be seen and admired even at a distance.
Some bulbs need to be divided. For example, daffodils multiply enough to form dense clumps, which compromises the flowers. Dig after flowering (while you can still find them), divide the clumps, and replant immediately or store until fall.
For all bulbs, including larger daffodils and tulips, don't remove or mow over the spent foliage until it has withered naturally. For this reason, it's best not to plant these long-standing bulbs in a lawn or other formal area, where the dying foliage can cause an unsightly mess. Try planting these bulbs in a field or meadow, or somewhere else that you only mow once or twice a year. Or plant them at the base of deciduous shrubs or in mixed beds or borders where later-blooming plants will draw attention from the spent foliage.
Nearly all hardy, spring-flowering bulbs require a period of "chilling" or cold dormancy before they will begin to grow and bloom. For gardeners in most regions of North America, providing this cold treatment is easy. Simply planting the bulbs in the fall and leaving them alone over the winter provides plenty of cold treatment. Just make sure to select bulbs that are hardy in your growing zone.
However, people who live in very mild winter regions (Zones 9 and 10) must select their bulbs very carefully. Daffodils should be planted in December or January (the coldest time of the year), but other hardy bulbs, such as tulips, crocuses, and hyacinths, may require special treatment in mild-winter areas. Gardeners in these regions of the country should select from among the many varieties that are rated best in warm spring and summer conditions.
Many tulips will grow well as annuals in the South if the bulbs are prechilled. Other good bulbs for warm climates include crocuses, hyacinths, lilies, muscari (grape hyacinth), colchicum (autumn crocus), and alliums (ornamental onions).
The easiest way to prechill bulbs is to store them in the refrigerator, where temperatures can be easily maintained at 40 to 45 degrees F. Store them in breathable mesh bags, like the ones they are often sold in at garden centers. Then, when they have chilled for the requisite number of weeks, simply remove the bulbs from the refrigerator and plant them either outdoors in the ground or in containers.
If you have enough space in the refrigerator, you can even plant bulbs right in their containers and remove the whole pot at the end of the chilling period. Either way, place containers of bulbs that you're forcing into a warm, sunny spot and then sit back and wait for the bulbs to send up their green leaves. After their blooming period is over, you can continue to water the pots, letting the foliage die down naturally, then replant the whole mass of bulbs in the outdoor garden.
The most popular bulb for winter forcing is undoubtedly the paperwhite narcissus, which requires no period of prechilling before it will blossom. However, you can also add variety and color to your winter or early spring displays by prechilling many other types of bulbs, then forcing them in containers for indoor bloom.
It's common for florists to sell containers of forced bulbs that are all of one type, such as dark purple or pink tulips. This makes a smashing display, but you can also be creative by forcing several kinds of bulbs of different colors or even different species to make a mixed display.
Unless you're using a large container or you have a good eye for natural design, it's best to experiment with only a couple of types of bulbs in each pot. Plant bulbs that grow to roughly the same height and whose flowers will complement each other in form and color (pink alliums and white Dutch crocuses, for instance).
Pots sold for forcing bulbs tend to have no holes in the bottom, because many people grow paperwhite narcissus in a medium of small stones instead of soil, and so drainage is not an issue. It is possible to grow other bulbs this way as well, but keep in mind that you probably won't be able to replant them outdoors after they have blossomed unless you grow them in soil. When forcing bulbs in potting soil, make sure the container has drainage holes in its bottom and that you place a dish underneath it to catch the excess water, as with any other houseplant.
Although tulips are technically considered perennials, many gardeners find that their bulbs are relatively short-lived and begin to decline over two or three years, producing smaller flowers and eventually dying out altogether. Unless your climate and growing conditions are ideal (hot, dry summers, cold winters, and well-drained soil), it can be difficult to coax some varieties of tulips into making a long-term commitment to your garden.
However, there are other types that, when given a little special care, will flower repeatedly and actually increase in size and beauty. These varieties are commonly known as "perennial tulips." One note: When buying Darwin hybrids, keep in mind that the ones with deep color will naturalize better than those with pastel colors.
To create the best conditions for perennial tulips, top-dress the planting bed with well-rotted cow manure, or add a slow-release fertilizer in the fall (9-9-6 or lower profile). After the flowers have finished blooming in the spring, deadhead the spent blossoms and allow the foliage to mature and wither naturally, so the bulbs can gather energy for next year's bloom.
Lilies are no more difficult to grow than other hardy bulbs, so long as you keep in mind a few of their important differences.
Plant lilies as soon as you get them, either in the fall or the spring. Because the bulbs lack the papery covering (known as a "tunic") that is common to other hardy bulbs, they can dry out quickly in storage.
Even more than other bulbs, lilies demand well drained soil. Dig the spot where you plan to plant lilies to a depth of at least 12 inches, remove rocks and add organic matter such as leaf mold or peat moss to improve both the soil's structure and drainage. Like other bulbs, lilies appreciate a little bone meal scratched in at the bottom of the planting hole, but do not really require other fertilizers at planting time. Instead, wait until the bulbs send up green leaves and then sprinkle a complete organic fertilizer around the plant and water it in.
Spread an organic mulch around lilies to help keep the soil moist and cool; use compost, well-rotted manure, or a longer-lasting mulch, such as wood chips or cocoa shells. As with other perennials, cover the bed over the winter with straw and/or evergreen boughs to help protect the bulbs from alternate freeze/thaw cycles.
During the flowering season, remove spent blooms, but try not to cut off more than a third of the stem, which can reduce the plant's vigor and longevity. This can be difficult to follow if you're cutting stems for indoor arrangements. So consider growing some lilies in perennial beds or borders, and others in a designated cutting garden.
Tender bulbs tend to belong to the summer-flowering group and include such popular garden specimens as dahlia, gladiolus, tuberous begonia, canna and calla lily (Zantedeschia).
Technically, these are not "true bulbs," because they don't contain a tiny flower and stalk inside of them. Instead, the plants grow from bulblike structures known as corms (gladiolus), tubers (dahlia, caladium), and rhizomes (canna). However, they are just as dependable as true bulbs and can be grown in much the same way.
These exotic summer-blooming bulbs can be integrated into the perennial garden, but because they are so popular for arrangements, they're often planted right in the vegetable garden or in a special cutting garden. Plant tender bulbs about the same time as beans and other crops, after the last frost date in spring. Then, around the first fall frosts, when the garden's tender crops are winding down, dig up the bulbs and store them away for the winter.
These tender bulbs vary in hardiness, and it's impossible to give general growing instructions for all of them; different plants have distinct preferences about light, and soil structure and fertility.
Gardeners living in Zone 8 or warmer regions can successfully overwinter cannas, callas and other types. However, by far the most popular way to grow these exotic tropical and subtropical natives is to dig up the plants around the time of the first fall frosts, allow the bulbs to dry for a short period, and then store them either in paper or mesh bags or placed in a shallow pan or box and covered with dry peat moss. Ideal storage conditions are dry, dark, and cool, around 40 to 50 degrees F.
* Taylor's Guide to Bulbs, Barbara W. Ellis (Houghton Mifflin, 2001).
* Bulbs: Four Seasons of Beautiful Blooms, Lewis and Nancy Hill (Storey, 1994).
* Daffodils for American Gardens, Brent and Becky Heath (Elliott & Clark, 1995).
* John E. Bryan on Bulbs, John E. Bryan (Macmillan, 1994).
* The Random House Book of Bulbs, Roger Phillips and Martyn Rix (Random House, 1989).
For many gardeners, there's nothing like a full perennial border with a crisp edge of lawn.
Perennial plants are the backbone of nearly every flower garden. Unlike annual plants, which must be replanted each spring, herbaceous perennials die to the ground at the end of the season, and then regrow from the same roots the following year. People grow perennial flowers because they are such easy-care, dependable performers, and because they offer an enormous variety of color, texture and form. Here are the basics of garden design, plant selection and care.
The lifespan, bloom time, culture and form of perennial plants varies greatly. Some species, such as lupines and delphinium, are so called "short-lived" perennials, with a lifespan of just three or four years. Others may live as long as fifteen years, or even, in the case of peonies, a lifetime. Bloom time may last for only two weeks each year, or may extend over two or three months.
Some perennials, such as primroses, require deep humusy soil and plenty of shade, while others such as threadleaf coreopsis and cushion spurge wither away unless they grow in well-drained soil and full sun. Some perennials contain themselves in a nice, neat mound, while others, such as gooseneck loosestrife, will take over your entire garden. Some species should be cut back in midsummer, while others, such as hybrid lilies, may die if you remove their foliage.
There are so many different species and cultivars of perennial flowers to choose from that few people ever become completely familiar with all the options. For the perennial gardener, books are an invaluable resource. They provide photographs for identification (and inspiration!), cultural information, a description of growth habits, bloom time, color and characteristics of special cultivars. Invest in a good how-to book that has cultural information, and a color encyclopedia to help you identify plants and plan your selections.
What's in a Name?
It may be hard to believe, but scientific plant names are used to avoid confusion, not create it. They are developed by taxonomists to ensure that the same plant is called the same name throughout the world, regardless of language. Scientific plant names are usually a combination of Latin and Greek.
Common names, such as "bleeding heart," are often used to refer to all the plants in a genus and are useful unless you want to ensure you are purchasing a 24-inch high, spring-blooming bleeding heart (Dicentra spectabilis) rather than the ever-blooming species known as the fringed bleeding heart, which is only 12 inches high (Dicentra eximia). To learn more about botanical names, look for a copy of Gardener's Latin by Bill Neal (Algonquin Books, 1992).
Dicentra spectabilis 'Alba': (old-fashioned white bleeding heart)
Dicentra: The first name is the genus. It is always capitalized.
spectabilis: The second name is the species. It is not capitalized.
'Alba': The third name, which appears in single quotes, is the cultivar (cultivated variety).
Fellow gardeners are another great source of information about perennials. They can give you firsthand details about bloom time, height, hardiness and cultural requirements, and, if you visit their gardens, you can also see for yourself what the plants really look like up close. Nothing beats seeing a plant in a garden setting, where you can observe how it is being used. You may even go home with some pass-along plants for your own garden.
There's just no way to know how a plant will do for you unless you give it a try. If it turns out to be too tall, the color is wrong, or the plant doesn't thrive, you can always move it and try something different.
Few if any "perennial gardens" contain only herbaceous perennials. Woody plants, such as shrubs, roses, and trees, are often incorporated to provide a backdrop for the perennial plants, or are used to fill in and give mass to the bed or border. Many gardeners include annuals or biennials in their perennial gardens to provide splashes of dependable color throughout the season. Bulbs are added for early spring color and ornamental grasses for their interesting textures and late-season beauty.
Traditionally, perennial gardens have been laid out in one of two ways: a border or an island bed. A border is typically a long, rectangular flower bed that is about two to four feet deep. The classic English perennial border, which was so popular in the first half of the 20th century, was often as much as eight feet deep and 200-feet long. But for most home gardeners, a better size is about three feet deep and about 12 to 15 feet long.
Borders are usually viewed from only one side, and are located in front of a backdrop. This backdrop may be created with shrubs, a hedge, a fence or a stone wall. A well-defined front edge is important. You may design a solo border, or a matched pair. When selecting plants, keep in mind that borders usually look best when there is a repeating theme of plants and colors.
An island bed is a garden that floats in a "sea" of lawn. The shape is irregular, with gentle curves and no sharp corners. It is usually designed to be viewed from all sides, with the tallest plants positioned along the center line of the bed, and the shortest plants around the edges. Island beds look best when they are generous in size. A good size for an island bed is 8-by-15 feet, with the tallest plants reaching a height of about five feet.
Of course perennial flower gardens sometimes look nothing like a traditional border or island bed. Rock gardens break all the rules, for the objective is usually to create an irregular, natural-looking rock outcropping where tiny alpine plants can be featured.
Shade gardens are often irregularly-shaped, because they follow the natural shade patterns of the trees above. Another emerging style for perennial gardens is the large, free-form garden. In this case, the garden is defined by a series of meandering paths that lead the viewer right into and then through the plantings. Perennial flowers can also be mixed in among shrubs, planted around your mailbox, used in woodland or streamside plantings, or even planted in containers.
The appearance of a perennial garden depends as much upon the shapes of your plants and how they are arranged, as upon their colors.
Height: You'll want to place the tallest plants in the back of the border, or in the center of an island bed, then work down in height, ending with the shortest plants around the edges of an island bed or the front of a border. Books and labels usually list the average mature height for a plant in bloom. Remember that many plants hold their flowers well above the foliage. This means that when the plant is out of bloom, it may be much shorter than the specified height.
Heights are also an average. When grown in poor, dry soil, a plant may be only half as tall as the same plant grown in rich, moist soil. Be prepared to move your plants around once you see how tall (or short) they really grow. Even the most experienced gardeners rearrange their plants (usually more than once!).
Width: A plant's width, or spread, is just as important as its height. Width figures given in books or on labels are also an average. The actual width of a plant will vary depending on soils, geographical location and the age of the plant. Be careful about locating slow-growers very close to rapid spreaders. The former may all but disappear by the end of the first growing season.
Spacing: Patience is a virtue, but when most people plant a perennial garden, their goal is to create a full effect as soon as possible. The challenge is to plant thickly, but not break the bank, or create a crowded, unhealthy situation two or three years down the line. When planting a grouping or "drift" of the same kind of plants, you can put them closer together to create a massed look more quickly.
Another trick is to place short-lived plants between slower-growing, long-lived plants. Most peonies, for example, have an ultimate spread of three feet, but it may take seven years for them to reach this size. While you're waiting, you could interplant with Shasta daisies, a fast-growing, short-lived plant that will provide a full look and plenty of flowers while the peonies get themselves established.
Drifts versus specimens: A garden planted with groupings of five or more plants of the same variety will display drifts of repeating colors and textures. In this type of garden, plants are used primarily as design elements that add up to a pleasing and integrated visual effect.
At the opposite end of the spectrum is the collector's garden, filled with onezies and twozies of all different kinds of plants. These are the gardens of people who simply love plants and want to have one of everything. The look of this type of garden may be a jumble of colors and textures, and maintenance is usually more challenging, but these gardens are about plants first, and design second.
When it comes to deciding which perennials to plant, most of us are not very deliberate about our choices. We succumb to a luscious photo in a catalog, stumble upon an irresistible beauty at the nursery, or a neighbor sends us home with a bag full of cast-offs. If you ever do set out to make an informed and deliberate choice, here are some of the things that you should think about.
Your site: Perennials, like all plants, will live longer and be healthier and more floriferous if they are planted in a location that suits them. Does your garden have sandy soil or is it heavy clay? Is it in the sun or shade? Is the soil moist or droughty? Is the pH high, low, or neutral? Is the site flat, gently sloped, or steep? A good reference book can help you figure out which plants will probably be happy in the growing conditions that you can provide.
Hardiness: If a plant is not hardy in your growing zone, it will not survive the winter. If you don't know which zone you live in, check a USDA Hardiness Zone Map. Though knowing your zone is very important, altitude, wind exposure, soils and snow cover can have a dramatic impact on plant hardiness, effectively shifting the hardiness rating for your garden by as much as a full zone.
For best results, choose plants that are well within your zone. You will probably be tempted by those that are at or even just beyond your growing zone. If you can afford to take the gamble (financially and emotionally), it can be very rewarding to discover that you can grow a couple of Zone 5 plants in your Zone 4 garden. Where snow cover is not dependable, a winter mulch of leaves or straw can help marginally hardy plants survive a cold winter. Well-drained soil is also a benefit. Heavy, wet soils will often heave and damage plant roots.
Northern gardeners concern themselves with the minimum temperatures that a plant will tolerate, but Southern gardeners must also pay attention to zone ratings. Many popular perennials, including lupines, peonies, and garden phlox, must be exposed to a period of subfreezing temperatures to produce a good display of flowers. Other perennials will simply not tolerate long periods of heat and humidity.
Color: In working with color, aim for a balance of integration and contrast. Too much of the same color can be monotonous, yet a cacophony of different colors can be jarring rather than pleasing to the eye. You may want to organize your garden around one color; or choose a theme such as pastels, cool colors, or hot colors. You can also experiment with different color themes in different parts of your garden—hot colors by the front door and cool colors in a quieter part of the yard.
Remember that few perennials are in bloom for more than a couple of weeks each year. Most of the time, plants are green, and it is their leaf form and foliage texture that are the "color" in your garden.
Bloom time: A perennial may be in bloom for two weeks a year or for as long as three months. If your objective is all-season color, choose several plants from each bloom season. When selecting plants for a spring garden, concentrate on those that bloom during April and May. After that peak, the garden may lack color for the rest of the season, but you will have achieved a spectacular spring display. For best effect, group at least two or three different varieties of plants together that will bloom at the same time.
Remember that specified bloom time is only an average. In California, April may be the peak bloom time for bearded iris, yet in Vermont, the same plant will not bloom until early June. Recording the bloom times of various perennials in your garden will become an invaluable reference. No book, no matter how good, will be as accurate as your own observations about when plants bloom and how they perform in your own garden.
Seedling, potted or field-grown: When purchasing perennials, try to get the largest, most mature plant that you can afford. The bigger the plant, the more quickly it will fill out and the sooner it will begin blooming. Typically plants are available in pot sizes ranging from 3-inch diameter to 12-inch diameter. Pot-grown perennials can be planted from spring through fall, and will suffer minimal transplant shock.
Some mail-order companies ship their plants bareroot (without soil). Bareroot perennials are usually available only in early spring when the plants are still dormant. The roots must be kept moist, and the plant should be put into the garden as soon as possible (within a couple of days). Once the plant is in the ground and has emerged from its dormant state, it will take hold relatively fast.
A few local nurseries still offer field-grown perennials. These plants are dug up when you come for them and they need to be transplanted immediately (within a few hours) to minimize transplant shock. Field-grown perennials are usually the largest and most mature plants around, but today most nurseries only offer container-grown perennials.
Vigor: Vigor can be good, but it can also create problems. Plants that are too vigorous can invade neighboring plants and gradually take over your entire garden. Determining a plant's propensity for invasiveness can be difficult, because poor growing conditions can render a normally invasive plant relatively tame, whereas in fertile soil, a normally restrained plant may exhibit invasive tendencies.
Look closely at plant descriptions and be wary of those described as "vigorous." This may be a euphemism for an invasive plant that you'll wish you never set eyes on. Perennials with a reputation for invasiveness include: bamboo, Macleaya cordata (plume poppy), Physostegia virginiana (obedient plant), Monarda (bee balm), Artemisia ludoviciana (Silver King artemisia), Lysimachia clethroides (gooseneck loosestrife), Tanacetum vulgare (tansy), Aegopodium (goutweed), and Boltonia asteroides.
Though most flowering perennials are dependable, easy-care performers, all perennial gardens require some maintenance. Here are the eight most important steps to ensure a healthy and floriferous garden:
Most perennials are not heavy feeders and they will be happy with one spring application of a low-nitrogen, high-phosphorus fertilizer (5-10-5). For established plantings, scratch in a good handful of fertilizer around each plant. Annual or biennial applications of aged manure or finished compost will restore trace elements and improve soil texture and water retention.
A perennial garden does not require as much water as a vegetable garden. Depending on where you live, if you select plants suited to your site, and mulch them well, you may not need to water at all. If you live where summers are very dry and you do need to water, try to water deeply and avoid getting water on the foliage (soaker hoses and drip irrigation systems are great for perennial gardens).
By early summer, a densely planted perennial garden will shade out most weeds. But a new garden, a spring garden or a garden that is more sparsely planted, will benefit from some kind of mulch. The mulch will keep weeds to a minimum and help retain moisture in the soil.
The aesthetics of the mulch are as important as the function. Your garden will look best with a finely textured material such as shredded leaves, dry grass clippings, peanut shells, cocoa hulls or shredded bark. Big chunks of bark, newspaper or straw will overpower your plants.
4. Neat Edges
A neat, cleanly defined edge between your lawn and flower bed will give your garden a professional look. You can achieve this in one of two ways: get a nice sharp edging tool and recut the edge several times during the growing season; or install some permanent edging. A defined edge will also help keep grass and weeds from growing into the bed.
Some kinds of perennials, including asters, chrysanthemums, phlox and salvias, benefit from being pinched back. Pinching creates a bushier plant that produces more blooms and is less likely to flop over. Pinch back the growing tips--using thumb and forefinger--once or twice during late spring. Not all kinds of perennials should be pinched. If in doubt, pinch a little here and there, and see what happens.
Some plants drop their spent flowers and seed heads. Others hold onto them for months, or even right through the winter. Removing spent flowers will keep your plants looking their best, and it often stimulates reblooming. It also prevents plants from expending their energy on seed production. After bloom, some plants should be shorn rather than deadheaded. This is true for creeping phlox, nepeta, hardy geraniums, daisies, pinks and lavender.
Many tall or weak-stemmed plants need support when they reach blooming size. Delphiniums and hybrid lilies are two prime candidates. But other, shorter plants can also benefit from some kind of support. Supports should be as invisible as possible. For individual stems, you can use bamboo canes. For entire plants you can use wire support rings. For loose and airy plants, try using a few thin branches. For best results, put the supports into position in early spring. That way the plants will hide the supports as they grow.
If your perennials are happy, most of them will need to be divided every few years. They may become too large for the space; the center or oldest part of the plant may die out leaving a bare middle; or the growth may become so dense that the plant is no longer blooming well.
Use a shovel to remove the entire plant from the garden and place the root ball on a tarp. Then you can either pry the plant into pieces using two forks, tease the pieces of the plant apart into different sections, or use a shovel or knife to cut the plant into several pieces. Plants should not be divided when they are in bloom or in full growth. In all but a few cases, this is a job for early spring or late fall.