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.
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
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.
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'.
in the Landscape
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.
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.
Mass Planting of Herbaceous Ornamentals
combinations, according to the
Birren system for outdoor color use are included
as a sidebar in this lesson.
perennials are useful for large border plantings (see Figure 9-2). If
these borders are 2-3 m (about 6-10 ft) in depth and 15 m or more (50+
ft) in length, a variety of heights covering a wide range of hardy perennials
can be used (from very low ground covers to plants 2 m or 6 ft high).
With proper planning, such a border can be aesthetic as well as interesting
from early spring to late fall each year. Annual flower plantings tend
to remain quite static throughout the summer season. Perennial plantings,
on the other hand, constantly change as different kinds progressively
come into bloom, then fade away as the season advances.
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
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.
Annuals as Shrubs and Hedges
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.
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.
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.
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.
Planning a Perennial Border for Color-Height Distribution of Flowers
Combine the height-color
distribution plan with one which considers the seasonal distribution
of flowers (see Figure 9-5). Figure 9-5A identifies the placement of
perennials that bloom in fall. The placement of summer flowering perennials
is identified in Figure 9-5B and the placement of spring flowering perennials
is identified in Figure 9-5C. The method for designing a seasonal distribution
plan for a perennial border is detailed below.
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.
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.
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
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.
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.
9-1. A Selection of 20 Easy to Grow, Readily Obtainable, Herbaceous Perennial
- Very hardy
- Good for front of dry sunny border
- Grows anywhere
- Useful for kitchen as well as front of ornamental border
- For front of border or rock garden
- Long flowering season
- A common native of Alberta
- Improved dark pink or red cultivars available
- Tough plant and good ground cover
- Large glossy leaves with red-purple tints in fall
- Excellent groundcover
- Profusion of dark purple-blue flowers clustered into heads
||pink or red
- Best in well drained sunny location
- Large daisy flower heads with bright yellow centers
- Valuable for cheerful early flowers
- Easily grown with tidy low foliage
||Juy - August
- A vigorous spreading plant for a dry place or poor soil
- Valuable for ferny foliage and long flowering season
- Tough, commonly grown but invasive daisy
- Useful for its long flowering season
||60 - 100
- Native plant with attractive daisy flowers
- Some greatly improved cultivars are available
||60 - 120
- Flowers held well above grassy foliage
- Sword shaped leaves and seed heads make an attractive contrast
with other plants
||60 - 90
- Stiffly erect plant with dense scarlet flowers
- Popular plant - will grow anywhere
||60 - 100
- Grown for its green and creamy white striped leaves
- Typical grass flowers are not showy
hybridus (T. chinensis or europaeus)
||60 - 100
||June - July
- Excellent garden plant
- Bright shiny globe shaped "buttercup" flowers
||90 - 130
- Large but very attractive plant
- Does well in semi-shade
- Excellent hardy plant
- Iris-type leaves
||90 - 180
- Cultivars available specifically developed for the prairies
- Cultivars include: Morden Pink, Morden Gleam, Morden Rose
and Dropmore Purple
||120 - 180
- A good plant for the back of a boarder
- Similar to delphinium
||July - August
- Cultivar 'Golden Glow' most often grown
- Useful at back of a large border
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.
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.
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:
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.
Flower Forms of Dahlias
Show (Ball) (more
than 5 cm diameter)
Pompon (5 cm diameter
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.
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
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.
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).
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.
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
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).
(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.
Tuberous Begonia Flower
roots with several buds or eyes can be cut into segments each with one
or more eyes (see Figure 9-14). The cut surfaces should be dusted with
a fungicide to protect against disease and the wounds allowed to dry
and begin healing before planting.
Division of a Tuberous Begonia
The Flower Forms of Double-Flowering Tuberous Begonias
can be taken from well developed shoots leaving 2 to 4 leaves on the
parent plant below the cut. A peat or peat-lite mix makes a good medium
for rooting. The humidity should be kept high to minimize wilting.
begonias flower best in partial shade and should receive no direct sunlight
after mid-morning. Like dahlias, they are extremely frost sensitive.
Once blackened by frost in the late summer or early fall, they should
be dug, allowed to dry until the tops wither, then cleaned of all soil
and fine fibrous roots. The tops should be removed as close to the tuberous
root as possible without damaging the root surface where new buds will
arise. The corm-like tuberous roots can be washed, dried, then stored
in dry peat moss, vermiculite, or sand at cool temperatures. Some references
suggest storing at 7 to 15°C, whereas others recommend 2 to 5°C. At
the lower range, growth is inhibited until the roots are removed from
storage. When stored at the higher range, buds swell and begin growth
by February or March. Once growth starts, the roots should be removed
from storage, planted in pots and placed in warm temperatures with sufficient
light. Tuberous roots, whether purchased or stored from the previous
season, should be started in pots by mid-March in order to obtain plants
in bud ready to flower by late May or early June.
tender plants that can be handled in much the same way as the tuberous
begonia include: caladium, giant summer hyacinth (Galtonia candicans),
tuberose (Polianthes tuberosa), ranunculus (Panunculus asiaticus)
and yellow calla (Zantedeschia elliottiana).
because they do not produce perennial woody top growth, have a limited
seasonal function as landscape material. On the other hand, woody plants,
both deciduous and evergreen, are much more useful in defining space
relationships and tying the structural elements on a given site to the
natural setting. They contribute to the landscape design and add interest
year round. Nevertheless, herbaceous ornamentals, if carefully used,
can enhance the landscape features and add color and interest during
the growing season. A judicious combination of bedding plants and herbaceous
perennials can add color to the home ground from early spring to late
fall, even in the relatively short growing season of Alberta. With a
careful choice of plant Species and cultivars, a gradual increase in
flowers can be achieved. For example, flowers of early spring bulbs
can be later joined by mid-season perennials and mass plantings of annuals.
The beauty can climax by mid-summer and gradually taper off as the annuals
decline and eventually disappear with the first killing frost. Fall
flowering perennials continue to add color until the onset of winter.