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Ornamental
 
                 
 
 
Design
Planting & maintenance
Integrated Garden Management
Common pests & diseases
 
 
 
 
 

Bedding plants

Many of the flowering plants in an ornamental garden are annuals, biennials or herbaceous perennials.

  • Annuals, also called bedding plants, are plants that complete their life cycle within one year. This means they germinate from seeds, grow leaves, flower, and then die. The following year, new plants must come from new seeds.
  • Biennials take two years to complete their life cycle, generally producing only leaves and roots in the first season with flowers appearing in the second year. A common biennial plant is the foxglove.
  • Herbaceous perennial plants live for at least three years, but go through a seasonal cycle of growing leaves and flowers that die down at the end of the season. The following year the plant regrows from the remaining underground tissues.

Note that woody perennials differ from herbaceous perennials in that the former have permanent woody tissue that remains above ground and growth continues from that every year. Shrubs and trees are classified as woody perennials.

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Design

Most ornamental gardens (also called beds or borders depending on their position) include a mixture of annual, biennial and perennial plants. Perennial plants, particularly woody perennials, give structure to a garden since they are present every year. They provide variation in height, shape and texture as well as colour. Annuals are mainly used for seasonal colour as they flower profusely and may also have bright coloured foliage. Different types of plants can be used as focal points in the garden at different times of the year, depending on their stage of growth. Plants can also be put in containers, such as hanging baskets or pots, and moved to areas where they will have an impact.

Think of your climate

Careful planning is required to create an attractive ornamental garden. First, think about the climate. Always select plants suitable for your environment or create a microclimate for them. The main climatic variables for the ornamental garden are temperature, water and light, with one extreme being hot, dry and sunny and the other being cool, damp and shady. Hostas will not thrive on a dry bank in full sun, while delphiniums produce few flowers in shady conditions. Gazanias, geraniums, wallflowers and stocks prefer warm, sunny spots, while begonias, lobelia, polyanthus, pansy and viola do best where the soil is moist and there is some shade. Frost is another factor that will influence the plants you select or where they are positioned. Plants may be described as half hardy (can withstand temperatures down to 0°C), frost hardy (can withstand temperatures down to -5°C) and fully hardy (can withstand temperatures down to -15°C). Some plants have brittle stems and cannot withstand strong winds, while other plants are very susceptible to the salt-laden air of the seaside.

Seasonal changes are another aspect of planning the ornamental garden. Ensure that there are interesting things to look at all year round. Annuals provide great displays in spring and summer, while perennial plants are often used to provide focal points in autumn and winter. Some common spring-flowering plants include daffodils, tulips, polyanthus, forget-me-not, primula, ranunculus, pansy and wallflower, while geranium, salvia, begonia, nicotiana, dahlia, impatiens, lobelia, petunia and verbena are plants that flower in the summer. Chrysanthemum, penstemon, aster, Liriope and Kniphofia produce flowers in the autumn, while some of the most well-know winter-flowering plants are the hellebores (winter roses).

Colour themes and shapes

Within a defined area of the garden, it can be a good idea to keep to a specific colour theme. Use a colour wheel to help you work out what colours mix well together. You will need to consider the height of plants, so that the tallest are placed in the centre of a bed or back of a border and shortest on the edge. Also look at the texture and shape of leaves and flowerheads. Try to place contrasting plants near each other, such as the large, oval, hairy leaves of a Bergenia beside the spiky, smooth leaves of a dwarf flax. An annual that makes a big impact with the texture and colour of its foliage is the ornamental kale.

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Planting and maintenance

Annual plants need to be replanted every year, with spring-flowering annuals being planted out in autumn (mid March-early April) and summer-flowering annuals being planted out in spring (late October-early November). Once they have finished flowering, the plants should be pulled out and placed in the compost. Some people may save seeds to grow the following year, and particularly in cottage-style gardens, seeds like cornflower and forget-me-not may be scattered throughout the garden to germinate and grow where they land. It is important to remember that for many plants, the seed collected may not produce flowers that are the same colour as the parent they were collected from. If colour is an important factor in the garden design then it is best to purchase seed or plants from a reputable garden centre or grower.

Most perennials should be planted in autumn or spring. When planting new perennial plants, take the opportunity to dig the area deeply to allow good root penetration and aeration and incorporate compost or specialist fertiliser, such as lime. Water the plant thoroughly and make sure it is firmly pressed into the soil. Large plants may require stakes or supports. Although perennial plants do not need to be replanted every year, they still require regular maintenance. Removing dead flowerheads from some perennials may encourage new flowers to form and prolong the flowering period. The underground tissues from which the new shoots of herbaceous perennials grow can get bigger and bigger every year. To prevent the plant overcrowding itself, it is a good idea to dig up, split and replant perennials every 3–5 years.

Soil conditions

Most ornamental plants do best in well-drained soils with a high content of organic matter. Some soils have a hard pan (impermeable layer below the soil level) and will need thorough digging to break up the pan If the soil has a high clay content and is very heavy, sand and organic matter (compost) can be incorporated into the soil to help improve the drainage. Gypsum is a good product to add to heavy soils. Digging in gypsum helps to break up the soil structure without altering the pH of the soil. Take care with fertiliser as what is good for some plants can damage others. For example, fluoride found in superphosphate can damage lilies, while rhododendrons prefer soil with a low pH. Applying too much nitrogen fertiliser can encourage plants to grow leaves rather than flowers.

Weeds

A weed is defined as a plant growing in a place where it is not wanted. White clover may be a detested plant in the garden but to a sheep-farmer it represents high quality stock food. Weeds will always appear in the ornamental garden, whether they germinate from seeds that may have lived in the soil for more than 10 years, are blown by wind, arrive with new plants or are carried in by birds or animals. Weeds not only spoil the look of the garden but can also compete with ornamental plants. A layer of mulch, such as straw or bark, can prevent weed seeds from germinating.

Well-planned gardens will have plants covering much of the soil surface at all times, giving weeds little opportunity to germinate. Hoeing or digging the garden may actually encourage weeds by disturbing the soil and exposing the seeds so they can germinate. If you are establishing a new garden, particularly if it is from an area previously in lawn, perennial weeds (which now include grass!) are best removed by spraying with a herbicide. The most common method of weed removal in the ornamental garden is by hand. This can be very healthy, providing exercise, time out in the fresh air and a chance to forget the stresses of everyday life.

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Integrated Garden Management (IGM) strategies for ornamental plants

Integrated Garden Management (IGM) is a set of techniques used to control pests and diseases without harming the environment or causing risks to human health.

So what does IGM mean for plants grown in the home garden? A good rule is to try to prevent pests and diseases and to deal with them quickly if you do observe them. To minimise pests and diseases make sure the bed or border is cleared of all plant rubbish before cultivating the soil. This is because fallen leaves may be infected with diseases, such as rust, that are then spread to other areas of the garden. Dispose of infected plant material by burning or deep burial. Choose plants that are suitable for the soil and location as they will remain healthy and resist attack from pests and diseases. In addition, fertilising and watering plants correctly will help to produce healthy plants. Buy only healthy plants, or if sowing your own seed make sure the seed is good quality. Planting should be done at the right time for that species. This means the plant will get established quickly and can better tolerate pests and diseases. In some seasons, sprays will be needed on some plants. Always follow the guidelines on the label so that the correct rate is applied.

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Some common pests and diseases found in the ornamental garden are described in the table below.

Pest/Disease Symptoms Control
Slugs and snails Irregular holes in plants and slime trails visible. Damage is worst in shady, poorly drained areas. Keep the area well drained. Scatter slug pellets around plants. Squash them when you see them. Encourage predators such as birds and hedgehogs.
Leaf rollers or caterpillars Young leaves rolled or stuck together and large, irregular holes in the foliage. Pick off caterpillars if this is practical. If widespread, spray with an insecticide, e.g. Derris dust.
Aphids Young growth is distorted and weak. Leaves may be covered with a sticky honeydew. Several species of aphids infest ornamental plants in warm settled weather. Keep the plants well watered. If desired, spray them as soon as colonies start to appear. Pyrethrum is an organic-approved insecticide that will kill aphids.
Rust Leaves have red and yellow pustules. Very common on hollyhock, geranium, and antirrhinum. Pick off and burn diseased leaves. Chemical control is not practical.
Club root Roots are swollen and distorted. Above ground, the plants are small and die off earlier than usual. Often affects wallflower and stock. Avoid growing stock and wallflower in the same spot each year. Apply lime to the soil for wallflower as it prefers an alkaline soil.

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