Intermediate level

All successful garden designs will feature a mix of different plant types. If variety is the spice of life then ensuring you have the 5 main plant groups in your garden is essential. Understanding the difference between annuals, biennials, perennials, shrubs and trees will ensure your garden is a year-round success. So let's take a look at the different plant types and how you can use them in the garden.

When you’re new to gardening, you tend to buy plants that simply look nice in the garden centre without considering what plant type they are. This can lead to disjointed gardens or though that look nice for a few weeks and then return to their bland previous state.

By understanding the 5 different plant groups of classifications, you can ensure your garden has both year-round interests and is set up to encourage wildlife into the garden. However, it can be daunting looking at the variety of plants on offer and trying to understand what should go where and how long the plant will live for.

Plant Type Groups Explained

The good news is nearly all plants can be split into different ‘lifecycle’ types or ‘classifications’ of plants. As you need all 5 in any garden knowing which group they belong to will help you work out exactly what plants you are looking for when shopping or growing.

Rather than getting overwhelmed, I believe it’s best to start with the most relevant to a new or weekend gardener.

To help you get more familiar with garden plant types, I’m going to group them into 5 areas:

  1. Annuals
  2. Biennials
  3. Perennials/Herbaceous perennials
  4. Shrubs
  5. Trees

1. What is an annual plant?

Annual plants germinate, grow, flower, potentially set seed if not sterile, and then die within a year.

Annual plants are the show-offs in the garden. They provide colour for one year and usually die off after Autumn.

Marigold annual plants

There are two main types of annual plant:

  • Half-hardy Annuals
  • Tender Annuals

Half-hardy annuals can be sown outside during the colder early spring months so they can get established. Tender annuals – like Busy Lizzies – cannot withstand frost or cold temperatures so can only exist outside in late Spring through to Autumn.

Examples of Annual Plants:

  • Impatiens walleriana – Busy Lizzie (Tender Annual)
  • Pelargoniums (Tender Annual)
  • Nastrutiums (Half-hardy Annual)
  • Cosmos (Half-hardy Annual)
Busy Lizzys
Busy Lizzies above are a tender Annual plant

Whats the difference between an annual and perennial plant?

The main difference is that annual plants only live for one year and then die. Perennial plants come back year and year and are considered a more long-term and ethically carbon-conscious way to garden.

Garden ninja Lee Burkhill planting a border with seedlings

2. Biennial Plants Explained

Biennial plants have a 2-year lifespan.

In year one, they germinate, grow foliage and establish their roots. Then in year two, they flower, set seed and die.

Examples of Biennial Plants:

  • Nigella damascena -Love in the Mist
  • Digitalis pupurea -Foxglove
  • Myosotis sylvatica – Forget-me-nots
Forget me nots in blue
Forget-Me-Nots above are a classic garden biennial and rapid self-seeder

3. Perennials & Herbaceous Perennials

This group of plants is where the real fun starts. These are plants that live for longer than three years, sometimes up to 30 years plus.

Herbaceous perennials come back year after year. So once they are established, they keep coming back every year keeping your garden borders full with minimal intervention from you apart from a good yearly prune and or some staking.

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Herbaceous perennials provide amazing value for money and provide essential pollen and a food source for wildlife in our gardens. There are hundreds of thousands of different species of herbaceous perennial meaning you have a huge choice.

Herbaceous perennials can be grown and propagated from seed, split from existing perennial plants or planted as bare roots. Making them incredibly versatile to help any kind of gardener plant up their garden on a budget.

Half Hardy vs Hardy Perennials

There is also a distinction between hardy perennials – those that can be left outside all winter (Rudbeckia or Ornamental grasses such as Miscanthus) and half-hardy perennials that need protection during the winter months (Dahlias are a good example of half-hardy perennials).

Pink Dahlia flower in full bloom
Dahlias are a popular half-hardy perennial that needs lifting each winter in colder climates

Examples of Herbaceous Perennials

Bright herbaceous plants in a border

Herbaceous perennials above come back year after year and make for rich wildlife-friendly garden planting schemes.

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4. Shrubs

Shrubs are the backbone or structure of any successful garden design and flower bed. They offer a year-round structure as they don’t disappear back to the ground each winter.

Garden Shrubs come in two distinct types:

  1. Evergreen shrubs that keep their leaves through the winter
  2. Deciduous shrubs that lose their leaves in the winter

Shrubs have woody stems compared to the fleshy stems of annuals, biennials and herbaceous plants. They can live far longer than the previous three plant types and offer a habitat for a much greater selection of wildlife, such as birds, mammals, insects and beetles.

A clean modern front garden makeover in Manchester
Buxus or Box Evergreen topiary balls above are a ‘formal’ shrub

Shrubs can act as permanent garden structures throughout the year. Using shrubs in a garden design or planting plants can help bring depth and year-round interest to a garden. They are important to help add structure and punctuation to a garden’s structure.

What is the difference between a shrub and a tree?

Shrubs differ from trees as they have multiple stems or branches rather than a single trunk. Shrubs are smaller than trees and can be pruned into distinct shapes. There are exceptions to these rules, with shrubs that can grow to the height of a tree or a tree that can be pruned into a multi-stem, for example.

Viburnum opulus in flower
Viburnum opulus above the Guelder Rose is a UK native shrub.

Examples of Shrubs

5. Trees

Trees are the garden’s final, vital, and sometimes overlooked plant type. Trees provide height, control shade, offer a habitat for birds and can help address flood risks.

Trees usually have one main stem (though they can be multi-stemmed) and grow far taller than shrubs. They, too, come in either evergreen or deciduous forms.

A Betula fastigata in a garden

There are a plethora of trees suitable for gardens of all sizes. In smaller gardens, fruit trees are a fantastic way to increase height without worrying about trees growing too tall.

Examples of Trees

  • Acer campestre – Field Maple
  • Acer palmatum ‘Bloodgood’ – Japanese Maple
  • Malus domestica – Common Apple Tree
  • Ginkgo biloba – Maidenhair tree
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How to design a flower bed with plant types

Now that you know the five different plant groups, you can use these to create fantastic flower beds. By planting a variety of the five groups, you can help encourage a host of wildlife to the garden helping mother nature and helping to reduce your carbon footprint along the way.

If you want to know more about how to arrange these plants, I suggest you read my flower bed design guide here or watch the video below.

Summary of Plant Types

Incorporating the five types of plants into your garden will help create rich, immersive spaces rather than seasonal throwaway flower beds. You’ll find yourself weeding less often, saving money and watching as wildlife flocks to your garden!

I’d love to hear from you on my TwitterFacebook or Instagram pages. If you have a gardening question then why not use the Garden Ninja Gardening Forum where hundreds of Garden Ninja members can help you?

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Happy Gardening!

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