Annuals, Perennials and Bulbs

Landscapes often include beds dedicated to pro-viding color. Such plantings generally consist of herbaceous plants that provide abundant bloom, colorful foliage and reliable growth. Well-executed color beds usually are the most noticed and visually appealing aspect of a landscape. Many of these, especially those that incorporate annuals and certain bulbs, tend to be high-maintenance affairs, so you’ll employ them to the degree that your client or facility is willing to pay for them. Herbaceous plantings consist of ornamental plants that we group into three categories: annuals, perennials and bulbs. A fourth group, biennials, includes plants that live for 2 years. For practical purposes, these may be treated as long-lived annuals. We’ll discuss the selection and maintenance of each type in more detail below.

A FEW NOTES ON DESIGN
Creative landscapers have devised an almost infinite variety of herbaceous-planting designs. Because of the vast number of plant varieties and flower colors available, the range of possibilities is nearly limitless. Some designers tend toward formality and create symmetrical, well-structured displays. Others prefer informal, natural-looking plantings. There is no absolute right or wrong in most cases, though some authorities have strong (and often widely differing) preferences. However, certain obvious guidelines are useful to follow. For example, if you mix different-sized varieties of bedding, make sure larger types will not hide smaller plants from view. Avoid overly complex designs—they tend to get lost, visually speaking. Also, be consistent with the character, formality and scale of existing landscape features.

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Some color combinations are definitely more pleasing than others, but do not be afraid to try new combinations. Some of the most dramatic plantings occur when designers use unconventional color mixes that would be considered “wrong” by some rules. Do not forget that bedding plants have one primary purpose: to look good. Following design guidelines should be a means to that end, not an end in itself. If guidelines hinder creativity, they are no longer useful. Also remember that, as in all matters of opinion, no particular look will please everyone. Make note of attractive displays you see, and take pictures if you have the opportunity. These are sure to spur new design ideas.

When you plan bedding displays, make scaled drawings based on bed measurements. After you decide on the kinds of bedding you’ll use, you can calculate plant-material needs based on plant spacing.

Spacing is an important matter (see “Spacing and plant-material calculations,” above right). Spacing plants too widely leaves the canopy open for too long, which may be unattractive and can increase weed problems. Therefore, do not try to save money by planting sparsely. Spacing plants too closely will force them to compete with each other and can increase disease problems. Further, it wastes money by utilizing more plant material than necessary. Proper spacing depends on the growth rate and habit of the plant variety and the ultimate size the plants will attain but ranges from about 6 inches to 1 or 2 feet for large bedding plants. Spacing should approximately reflect mature plant size. Bulb spacing falls within a similar range but do not space them wider than 10 to 12 inches because they will not fill in as do other bedding plants. When you install bedding plants, stagger the rows. This will not affect the number of plants you need but speeds up canopy closure somewhat.

You can rotate beds once, twice or more times annually, depending on the resources available. You can plant cool-season annuals in spring, follow them with summer annuals, after which you can install bulbs. Some professionals use plants such as chrysanthemums or kale for a brief splash of additional color after they remove summer annuals but before they install bulbs in the fall.

Another strategy gaining in popularity is intermixing cool-season annuals such as pansies with bulb plantings. This provides additional color as well as ground cover and helps distract the viewer from unattractive post-bloom bulb foliage.

PLANT TYPES
Annuals
, strictly speaking, are plants that grow, flower and die within the same season. However, this category is somewhat arbitrary because many “annuals” actually are tender perennials that simply are discarded at the end of the growing season. Annuals are further divided into cool-season and summer types.

Annuals are available in almost any color, texture or size you could want. Growers often supply “lines” or “series” of a species and variety that include plants that are similar in most respects but have different flower colors. These can be useful in color designs.

  • Cool-season annuals tolerate frost and typically do not thrive in summer heat (though exceptions exist). Landscapers in colder climates plant them in spring for early color and, to a lesser extent, in fall for color until cold weather ends the growing season. If this conflicts with your bulb-planting operations, however, you may wish to omit fall color where you’ll be installing bulbs. This partly is a matter of budget, because fall bedding may supply color for only a short time. In warm-winter areas, cool-season annuals are planted in late summer and fall for winter and spring bloom. In high elevations and other very cool climates, you can treat cool-season annuals as summer annuals.
  • Summer annuals mostly do not tolerate frost. Therefore, landscapers install them after the danger of frost has passed. Installation times vary according to region (see “Average dates of last killing frost in spring,” page 34). Summer annuals provide color for the duration of the warm season and are discarded when it’s time for the next changeout, often in September or October.

Bulbs, being long-lived, actually fit the definition of perennials. However, because they possess various qualities that set them apart from other perennial plants, it is convenient to group them separately. This group encompasses a large number of plants. Most traditional bulbs belong to the lily family (for example, tulips), the onion family (for example, daffodils) or the iris family. However, the term bulb is broadly applied to include members of various other families that produce underground structures such as tubers or rhizomes that, technically, are not bulbs. These include begonias, caladiums, cannas, dahlias, poppies and even some orchids, among others.

Many bulbs are quite hardy and should be planted in the fall for spring displays or even left in the soil permanently for naturalizing. Others are restricted to seasonal plantings and must be lifted and stored or discarded at the end of the growing season. Hardiness ratings for bulbs indicate only where they will tolerate winter cold. This does not mean you cannot grow them in colder climates during the warm season.

Whether you can reuse bulbs depends on the type of bulb as well as the care you’ve given them. For example, many kinds of tulips lose vigor and do not provide consistent bloom after the first planting. These often are discarded or given away. In any case, do not use them again for a formal planting where a non-uniform bloom would be noticeable—the money you’ll save by reusing them is not worth poor results.

Other bulbs, daffodils being a good example, perform satisfactorily for many years and naturalize well. Thus, you may wish to replant them in a location where you can leave them permanently or save them for future plantings. All bulbs benefit from good care and will come back stronger as a result. Still, if you intend to reuse bulbs, select types that are suitable for this purpose. If you are establishing a permanent bulb planting, use naturalizing types that will provide good long-term performance.

Perennials are long-lived herbaceous plants that regrow each year from underground parts. Some perennials live indefinitely, while others decline or die after several years. Compared to annuals, perennials are relatively low-maintenance, but they are not totally free of upkeep. For example, most periodically require division of their underground parts when dormant to maintain vigor. Still, perennials may be considered practical low-maintenance alternatives to annuals in spots where you want some color. They are not as reliant on continuous water and nutrients, and they avoid the labor-intensive changeouts that bulbs and annuals require.

Perennials tend to bloom for only a limited time—typically a few weeks to a month or so. Designers compensate for this by creating mixed perennial plantings that include species with a wide variety of bloom times. A well-designed perennial planting of this sort can provide season-long color. Because they increase in size every year, perennials eventually can provide impressive blooms.

The chart above and those on pages 38, 39 and 40 list bulbs, annuals and perennials commonly used in landscape plantings. These lists are by no means complete. However, the plants included account for most herbaceous plantings you see. Most of these genera and species have been well-developed by breeders so that a wide variety of flower colors, sizes and environmental adaptations are available. Remember that many other, less well-known types are available through specialty dealers. Also recognize that significant differences exist between varieties—differences that matter in a design. Acquaint yourself with specific cultivars before using them in plantings.

SPECIES
While reviewing the species in the tables, remember that these lists are not complete. They do, however, include the most widely used, well-developed lines of bedding plants available to the industry. Many lesser- known species are available from some suppliers and can perform quite well. Thus, omission from these lists is not meant to imply criticism. Also be aware of the following points as you use these lists:

  • Hardiness-zone ratings correspond to those shown by the map on the opposite page. Hardiness varies among cultivars of a species and among species within a genus. Further, environmental and physiological factors affect hardiness as well. Thus, consider the ratings given to be approximate.
  • Bloom times also are approximate. Yearly weather variations, site and exposure factors, climatic region and cultivar characteristics cause bloom times to vary.
  • Sizes of annuals have been listed in general terms because most commercial bedding-plant species are available in cultivars with a wide range of height and spread. Likewise, flower colors are not included because, again, breeders have created a large number of color options for most of the plants listed.
  • Exposures indicated in the tables are those that allow the plants to perform at their most optimum. However, cultivars of some species are available that thrive in exposures different than those listed. Further, many of these plants acceptably tolerate exposures outside their optimum parameters, even though they may not perform at their best.
  • Categories are, in some cases, somewhat arbitrary. For example, many suppliers consider several species, which are listed as bulbs, to be perennials, and vice versa. For practical purposes, this matter is of little concern. Whatever the underground structures may be, if the plant is hardy, you can leave it in the ground. If not, you must dig it up and store it during the dormant season. Further, certain species listed as annuals are actually perennial, even though we typically treat them as annuals and discard them after one season. • “Cool-season” and “summer” designations are climate- and region-dependent. Some cool-season species may be used only in spring and fall in hot-weather regions but all year in cool climes. Other species may tolerate frost but also thrive in heat. These are footnoted in the tables. • Perennials listed are all hardy to at least Zone 5, but many are hardier than this and will perform quite nicely in other zones. • Finally, remember that plants have just one botanical name, but often have several common names. Thus, the common names you see, while widely recognized, are not necessarily the only ones used for these species. There is no easy way to deal with this problem, so whenever possible, it is better to use botanical names to avoid confusion with other species that may share a similar common name.

SITE AND SOIL PREPARATION
Like all plants, bedding plants have specific environmental needs. Some prefer shade, others need full sun. Be sure you’re putting the right plant in the right place and using species appropriate for the season.

Proper soil preparation is, of course, important for all plants. However, it is especially critical if you expect to succeed with annuals. Annuals have only one season in which to provide blooms and must have good growing conditions from the start to perform to their potential. Even though most bulbs are virtually guaranteed to bloom, they, too, will yield better results if you treat their soil similarly.

Beds that receive regular rotations may need little preparation—the soil should be quite loose and, if prior care has been adequate, fertile and rich in organic matter. However, newly created beds or poor soil conditions may necessitate substantial inputs of labor and materials to bring the soil up to a quality that will allow annuals to thrive.

Till soil to a depth of at least 1 foot. Good drainage is important but so is water retention— annuals will languish if conditions are either too wet or too dry. Add generous amounts of organic matter to improve soil structure and water retention. Beds that have been worked and amended frequently may need less organic matter. Peat, finely ground bark and compost from various sources are commonly used soil amendments for seasonal beds.

Perennials enjoy similar soil conditions, but you should till the soil a bit deeper—to 18 inches if possible. Because perennials are relatively permanent, ensure you perform all necessary soil modifications before planting, when you can incorporate amendments more easily. While you are tilling the soil and adding organic amendments, also add fertilizer. Many analyses and brands of fertilizer are adequate for this purpose. A key point to remember is that you should avoid excess nitrogen. This promotes vigorous vegetative growth but often at the expense of flowering. Also, you should use a fertilizer with ample phosphorus and potassium.

Fertilizers such as 5-10-10 and 5-10-15 are commonly used and quite satisfactory, though many professionals use balanced fertilizers—10-10-10 or 20-20-20—with good results. Apply the fertilizer at the package-recommended rate and incorporate it into the soil along with the other amendments you are adding.

TRANSPLANTING
Annuals.
Landscape professionals rarely plant bedding from seed. It is far easier and usually yields better success to purchase young plant material from a reputable supplier. Select bedding plants that are pest- and disease-free, stocky, actively growing and have not been allowed to outgrow their containers. Bedding that has been held too long and has “stalled” will not perform well. Suppliers typically start to stock bedding around the time that frost is no longer a danger, and this is the time for planting. Don’t be tempted to plant too early when you see some nurseries stocking bedding plants while a danger of frost still exists.

Bedding plants typically are sold in flats, which hold cell packs of various dimensions and counts. Flats with higher plant counts also have smaller plants. Smaller plants can be purchased for less money per plant, but larger plants provide color a bit sooner, so there’s a tradeoff between the two. The time gained with larger plants is not great, so the most important factor is that the plants be of high quality, regardless of size.

Annuals in plastic cell packs are easily removed. Gently squeeze the cell to loosen roots and the plant should easily slide out. Plants with sturdy stems may be pulled out by the stem. However, if there is any danger of injuring the plant, turn the pack over and let the plant fall out.

To make it easier to implement your design, use some method of laying out the planting before actually placing the bedding in the ground. This allows you to make any needed fine-tuning to the design without having to dig up plants.

Some installers use wooden frames with string grids as planting guides. Others use augers to dig properly placed, well-defined holes in advance of the planting crew. Or, you can remove bedding plants from their packs and arrange parts of the design before actually planting the material in the soil. However, you should limit this practice according to weather conditions. Sunny weather can desiccate roots quickly, so this may not be appropriate on some days. Whatever method you use, it is better to plant bedding right the first time, for obvious reasons.

Transplanting is simple. Just dig a hole deep enough that the top of the plant’s roots are level with the surrounding grade. Soil mounded up around the stem is a practice you should avoid because it often promotes stem diseases. You can use a trowel, but well-tilled soil may be loose enough for you simply to use your hands. Small, powered augers sized for bulbs and bedding plants are available for planting holes.

Many installers place bone meal or superphosphate in the planting hole to supply additional phosphorus for quick establishment. Plants probably gain little benefit from this practice if the soil already is fertile and well-prepared. It causes no harm though, and many planters feel it is a good practice “just in case” soil fertility is deficient.

To the extent possible, avoid compacting the soil as you work in and around the bed. Work from the center of the bed outward to avoid disturbing the bedding you’ve already planted. When you have finished planting, immediately water the bedding thoroughly. Some landscapers apply mulch at this point. While it is true that this may conserve some water, the bedding will soon form a canopy that not only conceals the mulch but also performs the same function as the mulch. Therefore, the value of this is largely aesthetic. However, that is enough justification for many operations. Plus, the mulch provides additional organic matter when it is tilled in during the next changeout.

After you’ve installed bedding, the main problem becomes one of keeping the plants adequately irrigated until they are well-established. This may be easy or difficult, depending on weather conditions. But count on having to supply water as needed, perhaps daily, until the plants are established. The plants should become rooted well enough in the surrounding soil after a week or two for you to lessen the frequency of irrigation, though this will depend on your climate and weather conditions.

Bulbs. Plant spring-flowering bulbs in the fall anytime before the ground freezes. Although exact timing is not critical, an earlier planting is beneficial. This allows bulbs to establish roots during the relative warmth of fall. You probably will plant bulbs in the same beds you use for summer annuals. Thus, in practice, you won’t be able to install bulbs until you’ve removed the summer bedding—September or October in most parts of the United States. In warm-winter regions, you can also install intermixed cool-season bedding at the same time if you wish to use such a design. In regions with warm winters, you should refrigerate spring-blooming bulbs for about 4 weeks before you plant them in the fall. This helps prevent them from blooming prematurely.

Bulb designs are easiest to implement if you lay out the design on the soil surface beforehand. However, you cannot always tell the difference between bulbs of different varieties, so take whatever precautions are necessary to avoid mix ups. After all, you may not know if you’ve made such a mistake until the bulbs bloom, and then it is too late.

Because bulbs will not form a solid canopy, the planting pattern is much more apparent. Therefore, formal plantings require consistent spacing and straight lines for best appearance. Surveyor’s string or some other device can help you keep planting lines straight and spacing regular.

Of course, informal or “natural” plantings do not require such attention. These should relate more to other aspects of the landscape such as contours, rocks and other plants, and should be spaced with a more random appearance.

Plant bulbs with the roots down. Usually, this means pointy side up, but it’s not always obvious with some bulb types, so make sure you know which side is up before you plant. Planting depth varies according to species (refer to the planting depths given in the table on page 37). Ensure you plant bulbs at the proper depth, especially in areas subject to frost heave. Loose soil may be soft enough for you to use your hands to dig planting holes. Otherwise, use a trowel or an auger. Remember to water in bulbs after planting, as you would other bedding plants.

Perennials require planting treatment more similar to shrubs than annuals (see Chapter 5). Loosen soil around the planting site to a depth of 12 to 18 inches. If you wish to add fertilizer at planting, use a balanced product at one-half the label rate and mix it thoroughly into the backfill. As with any newly planted ornamental, be ready to supply frequent irrigation, if necessary, until the plant is solidly established. Surface mulching is beneficial for weed suppression and water conservation around perennials. Unlike annuals, perennial plantings usually will not form a closed canopy, nor will you work the soil in these beds regularly. Therefore, weed control may require greater long-term efforts in perennial plantings.

AFTERCARE

FERTILIZATION
Fertilization of annual plantings is generally a simple matter. After transplanting, apply a label-rate dose of fertilizer every several weeks. Use a product with a nutrient ratio similar to that which you used at planting. Often, bedding plants have achieved a closed canopy by this point. In this case, many grounds-care professionals prefer using a liquid-applied fertilizer, but granular products also are effective if you water them in properly. Further, granular fertilizations may last longer, providing nutrients for up to 6 to 8 weeks, compared to as little as 2 to 3 weeks with foliar feeding. Take care to avoid foliar burn if you use a liquid fertilizer, especially in hot, sunny climates.

Fertilize spring-blooming bulbs when the foliage is actively growing. Specialty “bulb food” fertilizers have appropriate nutrient ratios—the key is high phosphorus (relative to the other nutrients).

Perennials are less reliant on fertilization than annuals. Their more well-established root systems should be able to provide the plant with adequate nutrients assuming the soil is reasonably fertile. However, like shrubs, perennials may benefit from at least one fertilization in spring, using a balanced fertilizer. Some growers also recommend an additional fertilization, but this is not critical. Granular and foliar-applied liquids are both effective.

DEADHEADING
The practice of removing old flowers and young fruit, or deadheading, encourages more vigorous flowering in many species. Because seed formation draws on the plant’s resources, removing them will allow the plant to direct more of its energy to continued flowering. While some plants respond to this with more additional bloom than others, removing old flowers will improve the appearance of any display. Some varieties drop their old flowers on their own—these are called self-cleaning.

Deadheading is most important to annuals, whose short lives demand that nothing inhibit flowering. Perennials and bulbs may be able to increase their food storage for next year’s bloom if you deadhead them, though this will not usually promote reblooming in the same season.

DIVISION
Most perennials benefit from periodic division of their crowns (the underground portion of the plant, consisting of roots, stems, tubers or rhizomes). Some species grow best when you do this annually, while others may require it every 2 or 3 years. A few species are better off left alone. Because there is no way to generalize about frequency, you should familiarize yourself with the specific requirements of each species for which you care.

Division consists of nothing more than digging up the crown of the plant during dormancy and splitting it up into two or three sections, which you should replant immediately. Crowns may be pulled apart by hand, if possible. However, many species, especially those with woody or tough crowns, may require you to use shears or a knife to divide them.

Divide spring and summer bloomers during the fall, after they have died back but before the onset of cold weather. Divide fall-blooming perennials in early spring, before they have started to push growth. Division is less stressful to plants during cool weather. Also, irrigate prior to division if the ground is dry.

DISEASE CONTROL
Plant diseases can and often do prevent bedding plants from performing well. However, certain basic steps will minimize the potential for disease outbreaks in your beds.

The first step is to use only disease-free stock for planting. This seems obvious enough, but bedding plants quite often harbor unnoticed diseases. It pays to inspect plants thoroughly before you buy them.

Providing the best possible growing conditions for your bedding also minimizes disease problems. Healthy, vigorous plants resist disease much better than stressed plants. This means providing good water management (avoiding drought and saturated soil), adequate soil fertility and structure, and proper spacing to allow for air circulation.

Taking these steps will eliminate much of the potential for bedding diseases. However, problems still may arise now and then, especially when weather conditions favor them. When they do, you must take appropriate steps.

Inspecting plants before you buy them is an important step. Talk to other grounds-care professionals to find out which growers they recommend for providing disease-free bedding. Regardless of the supplier with whom you deal, always thoroughly inspect bedding you intend to purchase.

For example, bacterial wilt of geraniums is a common problem of vegetatively propagated geraniums. This disease is incurable so you must destroy any infected plants. Symptoms to look for include V-shaped yellowing between leaf veins, leaf spotting and wilting.

Viruses, mostly a problem on vegetatively propagated bedding (impatiens or begonia, for example) can produce a variety of symptoms. Viruses are not curable. Thus, as with bacterial wilt, you must destroy any infected material. Symptoms can include malformed plants or plant parts, stunting and yellowing. These symptoms might result from other conditions besides viral infection, but you should avoid such plants, whatever the cause. Other viral symptoms are more diagnostic, and include lines, concentric rings or other oddly patterned and colored designs on leaves. These are often quite distinct.

• Root and stem rots. Root- and stem-rot fungi, such as Pythium and Rhizoctonia, reside in the soil. When spring arrives, they are primed to attack new transplants. If enough moisture is available, and soil temperatures are adequate for fungal activity, infection can quickly develop if roots or stems contact fungi.

An important preventive measure is to ensure good drainage. However, if soil is already known to be infested, the best way to avoid root and stem rots is by treating the soil before planting to kill soil-infesting fungi. You should apply treatments when fungi are active and most vulnerable: when soil temperature at the 6-inch level is above 50°F and soil is moist. Fall is preferred, but spring also is appropriate if soil moisture and warmth are adequate.

If a bed has a history of heavy infestations, fumigation may be appropriate. Methyl bromide and Vapam are products used for this purpose. Fungicides may be adequate if the planting has experienced only minor outbreaks. Plus, unlike fumigants, fungicides labeled for bedding applications may be applied after the plants are installed.

Follow product-label instructions exactly. Fumigants in particular, but other chemicals as well, can be toxic to bedding plants if you apply them improperly or do not wait long enough after application to transplant.

• Stem, leaf and flower pathogens typically require wet surfaces to infect plants. Symptoms generally consist of necrotic spotting on the leaves and, sometimes, stems. The same pathogens also may cause flowers to rot. In the section on irrigation, we mentioned the fact that some plants enjoy overhead watering, while others do not. Those that don’t often are those that are susceptible to splash-dispersed diseases. These include both bacterial and fungal pathogens and require wet surfaces to spread. Therefore, keeping plant surfaces dry and providing good air circulation are the keys to preventing or stopping these diseases. Some can be controlled with chemical applications, others cannot. Correct diagnosis is critical, and you should obtain a disease reference, preferably one with photographs, to aid you in diagnosis.

Botrytis is a common bedding-plant disease. Petunias and geraniums are especially vulnerable, but many other species may be attacked as well. Botrytis thrives in humid, wet conditions and minimizing these factors should minimize this disease. Botrytis usually stops spreading once conditions are no longer favorable. Botrytis typically infects leaves and flowers, so when conditions improve, infected plants may recover. Also, a variety of fungicides registered for bedding are effective against Botrytis in case environmental conditions that favor the disease persist.

Powdery mildew is another common disease of many annuals and perennials, especially later in the growing season. Anti-transpirants provide a physical barrier against infection by powdery mildew. This is a tactic many growers use successfully. However, it is wise to test-spray a few plants to ensure they will not suffer any phytotoxicity. Again, fungicides are available for this disease if other measures are ineffective.

• Bulbs are susceptible to many diseases. In fact, some diseases that infect bulbs are the same pathogens that infect annuals and perennials. Proper drainage, good soil conditions, air circulation and minimizing wet plant surfaces likewise prevent most disease problems.

One situation especially harmful to bulbs is saturated soil. This can cause bulbs to rot if pathogens are present in the soil, as they often are. Fungal rots cause bulbs to be lightweight, soft, chalky, woody or dry and spongy. Bacterial rots cause bulbs to be mushy, slimy and foul-smelling. Plants so affected must be removed and destroyed. For future plantings, improve drainage and, if infestations are heavy, consider fumigation as discussed above.

Bulb rots also occur in storage. There, too, good air circulation around the bulbs is critical. Remove excess soil from bulbs you recently dug from beds and let them dry for a day or so before storing them. Also, do not pile bulbs deeply.

• Chemical treatment and disease identification. Many types of bedding diseases occur, some more commonly than others. Due to the variety of diseases you could encounter, you may find it necessary to seek the help of an extension agent for accurate identification and treatment recommendations. A good ornamental-disease reference is often adequate, however. In general, providing good drainage, reducing surface wetness and allowing good air circulation and sunlight exposure are the best ways to minimize these diseases. But remember that if cultural practices fail to prevent or reduce disease problems, fungicidal products are available for many ornamental diseases.

WEED CONTROL
Weed control is usually not a serious problem in bedding displays. Because of frequent changeouts, perennial weeds do not typically get a chance to gain a foothold, and seedling annual weeds tend to lose out to transplants, which have a head start. A healthy bedding display forms a canopy so dense that most weeds cannot thrive. Those that manage to grow usually are few enough to be pulled by hand. Thus, beds that have been worked for several years usually are reasonably weed free.

As discussed above, mulches are mainly of aesthetic value, but where the planting is thin or where weeds are unusually heavy, mulch may be beneficial as a weed suppressant.

Hand pulling avoids the use of herbicides, especially pre-emergents, that can be problematic in annual beds. Even if safe on the current planting, herbicide residues can harm future plantings that include species sensitive to the chemical you use. This is not to say that pre-emergents are useless in color beds. Just be aware that you may be limiting your planting choices for future changeouts. Perennial beds, of course, do not have this limitation. Just ensure the product is registered for the species present in the planting.

In spite of this, certain situations call for herbicide use. You may be creating a new bed or you may have inherited a weed-infested planting. If you are creating a new bed, be sure to use a systemic herbicide that provides a complete vegetation kill, such as glyphosate (Monsanto’s Roundup) or glufosinate (Bayer’s Finale). This will provide a weed-free beginning.

A pre-emergent also may be necessary in new beds until weed populations are reduced. In such cases, a number of products are relatively safe and effective (see “Pre-emergence herbicides for ornamental plantings,” page 42). Selective post-emergence herbicides also are available for removing grassy weeds and sedges from broadleaf plantings. Unfortunately, selective post-emergence broadleaf control in most bedding is nearly impossible because broadleaf products also affect bedding plants (nearly all of which are broadleaf species).

Spring-flowering bulb plantings often are less weed-prone than summer beds because they are installed just before cold weather. Still, spring weeds and, to a lesser extent, winter annuals, can be a problem.

Spot treating with non-selective herbicides is effective in situations where such use is possible. However, herbaceous plantings typically are so dense that the risk of drift is too great to chance. (See “Selective post-emergence herbicides...,” page 42, for a listing of selective post-emergence products registered for use in bedding sites.) Always read and follow all label directions. They contain important precautions that could apply to your plantings. The products listed in the table are not labeled for every bedding situation, so make sure any product you intend to use is appropriate for your site. Also, it is a safe practice to make a test application on a small area before using a product on a wide scale.

INSECT CONTROL
Insect control is frequently necessary in herbaceous plantings. As with all stresses, healthy, vigorous plants are more tolerant than weak ones. When necessary, however, do not hesitate to use control measures to quell a damaging infestation. The season is too short for most annuals to recover from significant damage well enough to provide a colorful show. See Chapter 16 for a discussion of insect pests.

IRRIGATION
For information on irrigation systems and strategies for bulbs, annuals and perennials—as well as turf—refer to Chapter 9.

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