A Beginner’s Guide to Biennial Flowers
Some of the most iconic and best-loved flowers in our gardens like Foxgloves, Sweet Williams, and Wallflowers are biennials. Although they take a little patience and planning, biennials really are worth the wait. Whilst annuals complete their entire lifecycle in one year and perennials will come back year after year, biennials are plants that have a two-year life cycle.
After sowing, they will put down their roots, form stems and leaves in their first year, and flower and produce seeds in the second year. This life cycle is really important to remember when planning out your gardens so that you know what will flower and when. Many biennials will also self-seed, meaning that you have a continuous cycle of flowers in the garden once established. Biennials offer excellent value, are often very pollinator friendly, and are brilliant at filling the gap between spring bulbs and summer flowers.
When should I plant my biennials?
Biennials should be sown undercover in the early spring, or you can direct sow them in May and June, though this will depend on the individual varieties that you’re planting. One of the most helpful things about biennials is that their leaves stay above ground during the winter, so you can see where your plants are and plan accordingly. Once they start flowering in the spring, you can cut them for displays and they will keep flowering. Generally, biennials will be in their peak blooming period in mid-late May, which is why you will often see them adding drama and structure to show gardens at the Chelsea Flower Show.
Here are some of our favourite biennial varieties to give you some inspiration:
Foxgloves
Foxgloves are a main feature in many gardens for a reason. These tall, spiked biennials provide structure and height to your garden while maintaining a cottage garden feeling. Often found in native woodlands, foxgloves come in a wide range of colours and are very attractive to pollinators, especially bees. Their poisonous nature also means that they are generally left alone by pests. You can plant them out in early autumn, and they grow well in sun or shade.
Lunaria
Lunaria 'Honesty' is another early-flowering biennial that will work well when grown in the garden. Its delicate purple flowers attract lots of butterflies, and their distinctive silvery seed pods are beautiful in their own right. They look particularly lovely when grown in drifts and will thrive in both sun and shade. Like many biennials, they are perfect for cutting, and they are ideal companions for foxgloves in any big arrangement.
Wallflowers
Wallflowers are the perfect biennial flower to add early season colour to your gardens. They come in a wide range of vibrant colours and have an intense fragrance. They are easy to grow, low maintenance flowers that look fantastic paired with Sweet Williams and Tulips in containers or flower beds.
Sweet William
The bright clusters of Sweet William flowers make them perfect for cut flower arrangements, whilst they add pops of colour to any cottage garden. They have a beautifully sweet scent and will attract pollinators to your garden.
How do I maintain my biennial flowers?
Biennials are often low maintenance and require little input once they’ve been sown. Many varieties self-seed, meaning that they will continue to grow new plants each year and you will get waves of flowers with very little effort.
It’s very helpful if you take a photo or a quick sketch of the seedlings as they emerge so that you can recognise them easily the following season. By doing this, you will avoid accidentally weeding them and they will grow in place, saving you more sowing next year.
