Plant Knowledge
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07/06/2021
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What Are The Differences Between Perennial, Biennial and Annual Plants?

Unsure of the differences between perennials, biennials and annuals? Carry on reading to brush up on your gardening terminology!

The terms ‘perennial’, ‘biennial’ and ‘annual’ categorise plants based on their life cycle. As a gardener, understanding when and how plants grow will determine which plants meet your garden needs, and how to make the most of them.

What Is A Perennial?

A perennial is a plant that lives for a long time, surviving three or more growing seasons. 

Examples of perennials include: Hostas (fortunei aureomarginata, sieboldiana elegans), Hellebores, Crocosmias, Phlox (‘Laura’, ‘Orange Perfection’, ‘Flame Pro Soft Pink’) and Hydrangeas (‘Phantom’, ‘Silver Dollar’, ‘Pink Diamond’).

Top tip: Ideal for beds and borders, perennial plants require enough space to grow. Consider their eventual height and spread to give them enough room to develop. It is possible to plant smaller plants closer together for fullness for the first few years, but they will need lifting and dividing as they grow.

Perennial Plants - Hydrangea Flowers

What Is A Biennial?

A biennial is a plant that has a two-year life cycle. It will establish from seed and develop foliage and roots in the first year (vegetative growth) before flowering in the second year (focusing on reproduction).

Examples of biennials include: Hollyhocks, Honesty, Foxgloves and Forget-Me-Nots.

Top tip: Some short-lived perennials are best treated as biennials because their flowering performs best in their first year.

Biennial Plants - Forget-me-not flowers

What Is An Annual?

An annual is a plant that completes its life cycle within one growing season. They grow, flower, set seed and die, all within the space of a year.

Examples of annuals include: Begonias, Cosmos, Marigolds, Pansies, Petunias and Sunflowers.

Annual plants - Pansies Flowering

Top tip: Annuals and biennials are quick-flowering plants, perfect for filling the gaps in beds, borders and empty containers with a welcome burst of short-term colour. You can collect the seeds from most of these specimens at the end of their flowering season. Sow the annuals in the following spring and biennials in early summer to be rewarded with lots of new plants!

 

Happy gardening!