By University of Alberta

The first three categories (Annuals, Perennials, and Bulbs) are treated together here under the following categories:

Introduction

Herbaceous ornamentals refers to all those non-woody plants that can be used attractively in the landscape. Some of the plants included in this category develop fairly woody stems by the end of each growing season, but are either killed back or cut back to ground level each winter.
Herbaceous plants may be annual, biennial or perennial in their growth habit (see Botany lesson, Table 3-2). Annuals are those which grow from seed, produce flowers and seeds during the growing season, then die, regardless of whether or not the environmental conditions continue to be favorable for growth. The life of these plants can be extended by preventing seed set, either by removing faded flowers or selecting clones or hybrids that are genetically sterile.
Biennials, by definition, are those plants which take two years to complete their life cycle. During the first growing season, they produce only vegetative growth, usually a rosette of leaves and (often) a storage organ, such as a fleshy taproot. If they are hardy enough to survive the winter, they produce flowers and seeds during the second year, then die. A few popular biennial flowers, such as hollyhock and sweet William, often survive as perennials for a few years. There are also selections available that flower from seed during the first season and can be used as bedding plants.
Perennials are those herbaceous plants that, once established, continue to produce new top growth and flowers each season. This growth can come from a hardy perennial crown and root system, an underground bulb, or other storage organ. Those that produce bulbs, such as tulips, daffodils and lilies are often dealt with as a separate group of herbaceous perennials. Included in this grouping are both hardy and tender bulbs. Tender bulbs are those that require lifting and special storage to bring them through the winter.
Many of the plants grown as annuals or bedding plants are true annuals. Others are perennials or modified biennials that flower from seed the first year, but are too tender to survive our winters. In all cases, these plants survive only one season and new plants must be started each year. For this reason, the term 'bedding plants' is a more appropriate reference for this category of herbaceous ornamentals than is 'annual flowers'.

Uses in the Landscape

Herbaceous ornamentals, because of their limited season as functional landscape plants, are usually of secondary importance to landscape planners. Woody plants (both evergreen and deciduous) are much more useful in defining space relationships and tying the structural elements on a given site to the natural setting (see Woody Ornamentals lesson, Planting Design). Herbaceous ornamentals serve more as 'cosmetics' that, when used carefully, can enhance the landscape features and add color and interest during the growing season.
Bedding plants are particularly useful for mass plantings of solid, brilliant colors in both beds and borders (see Figure 9-1). Their use should be mainly confined to the outdoor living area of the yard, where their beauty can be enjoyed from the patio, deck or family room picture window. Masses of solid color are usually more effective than mixed colors. This is not to say that masses of different colors cannot be used together. Color planning, however, is influenced by light and shadow, climate and humidity. Therefore, color theories (which apply where lighting is controlled) must be modified. Nonetheless, it is possible to use both complementary and analogous colors for harmonious results.

Mixed borders can be an attractive garden feature and may be more practical than a purely herbaceous perennial border for the average city lot. Such a border may be a combination of woody shrubs and perennials, perennials and annuals, or a mixture of shrubs, perennials and annuals. If early spring flowering bulbs are included in a perennial planting, it is advisable to replace them with bedding plants as the bulb foliage dies back after flowering.
Although woody plants are preferable to herbaceous ones for foundation plantings, one may not wish to spend the money required for shrubs, especially for summer homes or cottages that are closed-up for the winter. Tall, massive perennials, such as bleeding heart or peony, and annuals such as castor bean and kochia, can serve well as seasonal shrubs. Some can even be used to provide summer hedges (see Figure 9 3). Some herbaceous ornamentals are very useful as accent plants in a foundation planting of woody material. Small groupings of bedding begonias or tuberous begonias, for instance, with evergreen shrubs as a backdrop,can be very striking and require a minimum of bedding plants.

Figure 9-3
Annuals as Shrubs and Hedges

Planters and hanging baskets of various kinds and sizes are very useful containers for bedding plants. Usually, a combination of upright plants and trailing or cascading types work well in most types of containers. It is not recommended to use perennials or woody plants in planters unless the containers are large and well insulated against severe winter temperatures.
Annual vines, such as scarlet runner bean, canary creeper and morning glory, can be useful to cover bare or uninteresting walls, old stumps, gazebos, or trellises. Annual vines can also be useful for covering rough or unsightly areas of ground (or compost piles, etc.). Hardy perennial and woody vines (lianas) however, may be more effective cover plants. Some examples are clematis, Virginia creeper and the Dropmore scarlet honeysuckle.

Culture

Selection and Planning

The Alberta Horticultural Guide should be used to select those bedding plants and perennials that perform well in a specific location and are hardy in Alberta. Those sections pertinent to this lesson are reprinted (as a sidebar) through permission of Alberta Agriculture.
Three factors must be considered when planning for perennials: color, height and season of bloom. The object is to have a flower garden which is interesting and colorful from spring to fall. In order to achieve this, it is best to prepare detailed plans. On a sheet of graph paper, an outline drawing of the property can be made (to scale) showing the position of permanent structures and the garden beds and borders to be developed. It may be desirable to make larger diagrams of the major planting areas, particularly a perennial border if one is to be included. The border can be outlined to scale on the graph paper and sheets of tracing paper or onion skin used as overlays to develop appropriate height zones and color zones. Figure 9-4 demonstrates a method for determining the placement of herbaceous ornamentals within a border. The plan identifies the areas to be developed through considerations of the height and color of plants.

Figure 9-4
Planning a Perennial Border for Color-Height Distribution of Flowers

Figure 9-5
Planning a Perennial Border for Seasonal Distribution of Flowers

To make sure of an attractive combination of flowers blooming in a perennial border through spring, summer and fall, sketch the locations of plants on sheets of tracing paper laid over an outline of the bed. If you use the height - color distribution plan as the [bed] outline (Figure 9-4), your final plan will include height-color distribution as well. On the first sheet of tracing paper, [select] tall fall-blooming varieties; draw these in as clumps (light green) spaced along the back. Then add complementary fall plants (also indicated in light green), placing medium-sized ones in the center and short ones towards the front (see Figure 9-5A).
On a second sheet of tracing paper laid over the first, plan your summer blooms. Since most plants that flower in summer are medium-sized, select these first as your main display; draw these in as clumps, concentrating them in the center of the bed and locating the plants (indicated in medium green) in some of the open areas not already occupied by fall flowers. Then place in front and back, a few tall and short summer-blooming varieties whose colors will complement the flowers you have chosen for the center.
On a third sheet of tracing paper laid over the other two, plan your spring-blooming plants (dark green) in the remaining spaces (see Figure 9-5C). As most spring perennials are short, they naturally look best in the front of the bed. Some medium-sized and tall spring-flowering plants should be interspersed in the center and back. Now you can trace the outlines of your fall and summer displays through to the top sheet. If your seasonal distribution plan was created in conjunction with the height-color distribution plan, you are ready to select and determine perennial border plants that reflect height-color-season of bloom considerations.
Any gaps on the finalized plan can be filled with bulbs or annuals in desired quantities. Although height must be taken into consideration to prevent taller plants from hiding shorter ones, there should not be a rigid demarcation of height. A gentle blending of the planned height zones will help to prevent monotony. Once this has been achieved, specific plants can be chosen (using reference books and catalogues) for each designated height-color area and seasonal distribution area. For convenience at planting time, include a legend in the margin of the plan that details the mature spread of the plant and the time and length of its blooming period.
Considerable planning is required for perennial flower beds and borders. The majority of perennials have a definite (limited) season of bloom. If this is not taken into consideration, succession of bloom will not be achieved and the garden will not be alive with bloom throughout the season.
To achieve a continuous display of blooms, it is necessary to make the border more than one row deep. The border should be at least 1.5 m (5 ft) deep or wide. From the standpoint of maintenance, a border wider than 3 m (10 ft) is cumbersome. The length of a border can be determined by the space available. For most residential lots, the border length is not likely to exceed 20 m (65 ft).
The shape of the perennial border may be a strict and formal rectangle or, possibly, an L shaped combination of two rectangles. A natural, gently curved edge makes the planting appear less formal and adds interest by providing a variation in the width of the border. It also allows for a variation in the number of height zones along its length. A scalloped or patterned edge not only detracts from the beauty of the flowers but can make lawn edge maintenance more difficult. It is easier to use a lawn mower along a straight or gently curved edge than along sharply cornered edges. A row of flat bricks laid at the interface of the lawn and border can further reduce the requirement for trimming.
In order to produce a sense of balance in the border, it is best to limit the height of the tallest plants to approximately one half the width of the border. Edging plants are the shortest in a well planned border and should provide a good ground cover that remains attractive throughout the season. Bedding plants may be used as edging material to achieve an attractive continuity to the front of the border, particularly if early spring flowering bulbs are used (i.e., those which require replacement once their flowers and foliage fade).
To create unity, color groups should be repeated at regular intervals throughout the border. It is best to plant in groups that imitate the shape of the border (rectangles for a strictly rectangular border, soft curved areas for a naturalistic or informal border). More than one type of plant is used in any one color zone to provide blooms in succession. This means that color zones will overlap height zones. Furthermore, not only should these color zones repeat throughout the border, but the actual kinds of plants should repeat as well, although to a lesser extent.
To assist in the selection of hardy perennials, it is necessary to use reference material that describes their height, spread, color and season of bloom. It is best to select six to ten basic perennials that bloom successively throughout the season and can be used in the various height and color zones of your plan (see Table 9-1). Others that may be less dependable (or of more limited season of bloom) can then be chosen to round out the planting. A well planned border of relatively few, well-chosen, dependable kinds, appropriately repeated throughout the length of the border, are more attractive than a hodge-podge of many kinds of different plants. Furthermore, plants provide the best effect when planted in groups of three or more. Exceptions are large, massive plants, such as the peony and common bleeding heart, which are best maintained as individual plants within the border.
edding plants are very versatile and can be used in mass plantings of solid color in beds or borders of various dimensions . They are also well adapted to growing in planters and hanging baskets. The benefit of using bedding plants is that a different combination of plants and color schemes can be used each year. Depending on the color of the house, garage, fence or other permanent features of the yard, choice of color schemes for the garden may be somewhat restricted. In any event, bedding plants should be chosen with care and considerable thought given to the color of the blooms and the mature height of the plants.

Table 9-1. A Selection of 20 Easy to Grow, Readily Obtainable, Herbaceous Perennial Flowers

Propagation

Annuals

For the most part, annuals are propagated from seed and can be grown from seed by the homeowner. Some kinds germinate easily and can be self-perpetuating once they have been introduced (e.g., California poppy and nasturtium). Many cultivars are hybrids which either do not produce seed or do not come true from self-seed. For these, new seed must be purchased each year.
A limiting factor in starting annuals from seed indoors is light (see Plant Nutrition lesson, Principle of Limiting Factors). If plant growth is thin and leggy, natural light is insufficient and should be supplemented with artificial light (see Time of Planting). Many people buy annuals as bedding plants which have been produced from seed by greenhouse operators. A few common annuals or bedding plants are propagated from cuttings, the prime example being the large-flowered bedding geraniums.

Tender Bulbous Ornamentals

Plants that produce a bulb or similar underground storage organ are perennial in growth habit. Those that are hardy in our climate can be used and handled in much the same as any other hardy herbaceous perennial. However, those that are tender must be treated as bedding plants if they are to be used as garden plants. Because such plants produce storage organs, it is possible to save these structures, store them over winter and replant them in the spring (see Figure 9-9). For this reason, they can be considered as special crops. The special aspects of handling a few popular plants classed as tender bulbous ornamentals are given in thissection:

..Dahlia
..Gladiolus
..Tuberous Begonia

Dahlias

There are 12-14 classes of dahlias, ranging in flower form from singles through anemone flowered, colarette, cactus, decorative, ball and pompon to miniatures (see Figure 9-10). Propagation is by division of the tuberous roots (see Figure 9-11), rooting cuttings taken from the new shoot growth in the spring, or planting seed. The dwarf bedding type of dahlia, such as the Unwin Hybrids, is invariably started from seed indoors or in a greenhouse. These dwarfs also develop storable tuberous roots but flower best and remain more uniform in growth habit if started from seed each year.

Figure 9-10
Flower Forms of Dahlias

Single	Anemone
Collarette	Peony Flowered
Formal Decorative	Informal Decorative
Show (Ball) (more than 5 cm diameter)	Pompon (5 cm diameter or less)
Cactus	Star
Semi-cactus

Figure 9-11
Division of a Dahlia Plant

Dahlias are very frost sensitive and should be planted outdoors only after all danger of spring frost is past. Use of hot caps may permit earlier planting. Tuberous roots can be planted a week earlier than green plants.
Tall, large-flowered dahlia cultivars require poles or stakes for support. It is important to place the stake at the time of planting to avoid damaging the tuberous roots. A short stake may be used and replaced later with a support stake of the required height. Dahlias require large amounts of water and, if they do not receive sufficient water, their growth and subsequent flowering stops.
After the plants are blackened by the first killing frost of early autumn, the stalks should be cut back to within 10 cm (4 in) of the ground surface and the roots lifted. Most references suggest cleaning the roots of soil and storing them in a dark, moist, cool place(3 to 6°C). Thin or stringy roots should be wrapped in moist sphagnum moss or coated with paraffin to prevent shriveling. However, roots have been found to store better if left undisturbed in the clump of soil adhering to them at the time of digging. The soil is allowed to dry out completely during storage in a dark, cool place and, unless the roots show evidence of shrinking, no additional moisture needs to be added. Dahlia roots should not be saved from any plant that showed evidence of virus infection during its growing season.
In the spring, the roots are removed from storage, cleaned of soil (if necessary) and divided with one strong eye to each root (see Plant Propagation lesson, Division). Because dahlia roots do not possess the genetic capability of initiating adventitious buds, it is essential that each tuberous root contain a small portion of stem where the buds are located.

Gladiolus

The gladiolus (glad) is not a particularly useful flower for enhancing the garden landscape but it does make an excellent cut flower and is popular in flower shows, where the competition among glad fanciers can be very keen.
The glad produces a corm (rather than a bulb) which can be dug and stored over winter. Glads propagate naturally through the formation of baby corms or cormels around the edge of the main corm during the summer season (see Figure 9-12). These cormels may be harvested in the fall, stored slightly moist over winter and planted out in nursery rows in the spring. By fall, corms of varying size will have developed from these cormels and many will be of flowering size (2.5 to 3.5 cm (1 to 1 1/2 in) in diameter or larger).

Figure 9-12
Gladiolus Corm Plus Cormels

Glad corms can be planted as soon as the soil is worked in the spring. In order to ensure a succession of blooms, glad corms can be planted at 7 to 10 day intervals until the first of July. Although there are several buds present on each corm, only one (occasionally two) will develop into a shoot. Each shoot produces a central flower spike and a succession of grass-like leaves arranged in overlapping fashion in two opposite rows. As the plant develops, the original corm shrivels and disintegrates. A replacement corm forms above it at the base of the new shoot. For each corm planted, therefore, only one replacement corm is produced, keeping the population of corms rather static. Only when two shoots emerge from a corm are two replacement corms formed. However, to increase the number of corms, very large corms (well above the minimum diameter for flowering size) can be cut into two or three segments. Each segment must have a strong eye or bud. The segments should be dusted with fungicide before planting to prevent disease. In this way, two or three replacement corms will be assured for each original corm sacrificed. During the growing season, it is especially important that moisture does not become limiting during the critical period, when the new corm is forming and developing its own root system.
Glads should be left in the garden until they are severely damaged by hard frosts (usually early to mid-October).They should be dug, the soil removed and the plants bundled in sheaves of convenient size for hanging to dry and cure. Some references suggest cutting he tops back to within a few centimetres of the corms and allowing the corms to dry a few hours in the sun before storing to cure. In either case, the corms should be cured by storing for two to three weeks at 27 to 35°C. When the curing is complete, the corms will be firm and the shriveled remains of old corms, the stem and the husks can easily be removed. Some references suggest leaving a few inner husks around the corm but this makes the detection of any corm rotting diseases difficult to detect. Corms should be sorted and those that show evidence of disease should be discarded. Dusting with a fungicide or fungicide-insecticide powder is recommended prior to storage in shallow trays or boxes at 5 to 10°C.
Other tender bulbous plants that can be handled in much the same way as the gladiolus are acidanthera, anemone (Anemone coronana), Ismene-lily (Hymenocallis narcissiflora), Mexican tiger flower (Tigridia pavonia) and montbretia or tritonia (Crocosmia x crocosmiiflora).

Tuberous Begonia

Tuberous begonias (see Figures 9-13 and 9-15) can be propagated from seed. ~soft terminal stem cuttings or division. Propagation from seed is the most difficult method. If started in February in a greenhouse, plants of flowering size can be produced by summer. The seed is very fine and, therefore, requires a very fine seeding medium. The seed must be barely covered and kept at a high humidity until germination occurs and the young seedlings have established roots. The surface of the sowing medium must be kept uniformly moist and the temperature held at 20 to 22°C for uniform germination.

Figure 9-13
Tuberous Begonia Flower

Figure 9-14
Division of a Tuberous Begonia