In this article, we will be discussing how identifying plant groups in containers can help define your garden. In my various articles, you will know that I talk about the various plants that can be grown in containers, but I have not talked much about what defines each group.
This is because each group has a different role in the garden and this article will discuss this role.
Plants fall into 7 categories that are defined by their length of the life cycle, the size it grows to, its shape and its growing habits, as well as their physical structure. This article explains how plants are grouped and how they will behave in your container garden.
ANNUALS AND BIENNIALS
Plants that germinate, form stems and leaves, flowers and then set seeds and die in one year are known as annuals. These are an ideal group of plants for short-lived spring and summer displays. The plants are further divided into hardy annuals that can withstand frosts and tender types that can only go out into the garden when the frosts have passed.
Most annuals are bedding plants and can be sown from seed from shop-bought species or saved seed stock, or they can be bought as young plants. What surprises people is that some bedding plant often seen in gardens are actually tender perennials, but they are often treated as annuals as they would not survive the cold weather.
A biennial plant lives for two growing seasons; germinating in year one, whilst forming stems and leaves. After overwintering the plant flowers, setting seed and dying in the second. This includes plants like forget-me-nots and foxgloves.
This group of plants lives for more than two years and often for many years. They emerge from underground roots in spring, produce stems and leaves, then flower and set seed, before dying back into the ground in autumn.
Most perennials become dormant in winter, although some perennials are evergreen and retain their colour and leaves all year round. Some die back to a woody base rather than roots but they are still perennials.
Some perennials are tender and only come back to life in spring if you have protected them during winter or by bringing then undercover inside a greenhouse or conservatory. These tender perennials are often treated as annual for short- term colourful blooms and forms.
This group is divided into 5 categories:
- The true perennials that emerge and die back to their base each and every year.
- Evergreen perennials that give colourful leaves all year round and often flowers at a certain time of the year.
- Woody perennial that retail a woody framework during winter and do not emerge from roots underground.
- Ferns that are grown for the leaves and many of them retain their leaves in winter as they are an evergreen perennial.
- Grasses are a large group of perennials that either emerges from a base or that are evergreen.
When I say that perennials are long-lived this is not true for some of them, as they can die after a few years. Plants like sea holly often die within 5 years of active growth, so they are exceptions.
MARGINALS AND WATER PLANTS
Plants that thrive in water fall into two categories: Marginals and aquatic plants. Marginals tend to grow in shallow water usually up to 15cm deep. Aquatic plant includes water lilies and generally grow at depths between 30cm and 1.9m deep.
Ideally in natural ponds will include a range of marginal and deep water aquatic plants to create a balanced ecosystem, as well as use a few ‘Oxygenators’. These are fast-growing, submerged plants that release oxygen in the pond. These complete for nutrients with pond weeds and algae and therefore keep the water clear. Examples include Hornwort (Ceratophyllum demersum) and Ranunculus aquatilis, which are non-invasive oxygenators.
This group include all plants that form solid growth structures, such as corms, rhizomes, tubers and true bulbs. These are one of the mainstays of the container garden in spring and summer, where you often see their colourful bloom everywhere. If you what to know the difference between the 4 types then it is best to consult my glossary of gardening terms.
This group includes tulips, daffodils, hyacinths, irises, gladioli and many others. If you want to know what bulbs can be grown in containers then I suggest you read my articles on this (Bulbs that can be grown in containers, part I and Bulbs that can be grown in containers, part II
These are woody-stemmed plants that produce a permanent framework of branches that rise from the ground or a central trunk to create a bushy form.
The shrubs can be deciduous or evergreen and they are the main features of most gardens. There is a further category of subshrub which can be seen as a plant that divides between being a perennial and being a shrub; it has both characteristics.
Shrubs include ground huggers such as heathers to tree-like Mock oranges and tall bamboos. They provide interest for all 4 seasons from their structure, textured leaves, decorative flowers and fruits, and often colourful leaves in autumn. Shrubs can be made into features by pruning and training evergreens such as box in what is known as topiary.
Trees are not often seen in the container garden but they can be used. These provide the main architecture inside the garden. They are grown for their flowers, bark and foliage, often colourful in autumn. The trees can be either deciduous or evergreen, where they can form a spreading, rounded, conical, weeping or columnar canopy of leafy branches from a central trunk. This leads to trees of all different sizes, shapes and heights.
This is a group of woody-stemmed perennials that are used to climb over structures or through other plants. They climb by different means; twining climbers such as clematis use leaf stalks, tendrils or stems to coil around supports. Others like roses use thorny stems to act as hooks to grip on to trellises.
Self-clinging climbers such as Parthenocistus and ivy attach themselves to support using adhesive pads or by aerial roots. Climbers can be either evergreen or deciduous, fast or slow-growing, so you do have a choice. They may die back each year or they may be shrubby climber developing a more substantial and permanent presence in the garden.
Woody climbers require sturdy support to hold their stems or they die back each year, which is suited for smaller plots.
In this article, we have discussed what identifying plant groups that can be used in the garden. You now understand that there are 7 groups often used in the garden from annuals, biennials, perennials, water plants, marginal, bulbs, shrubs, trees and climbers.
It is up to you to what to have in your container garden, but if you want a balanced garden, it is suggested that you have one from each group. If you do not have a pond then obviously marginal and water plants can be overlooked. The more varieties that you use, the more interest you will generate for all 4 seasons, as you can differing colours, forms, structure and points of interest.
If you have any questions that you wish to make, please do so in the comment box below.
Grow the right plant group to make an instant impact.