You’re probably familiar with annual and perennial plants. Annual plants grow and live only for a single year, producing some of the brightest flowers available in order to attract lots of pollinators, to set seed before the plant dies.
Perennial plants are also very beautiful, with the added benefit of being reliable bloomers. They will flower year after year as long as you care for them properly, but what about biennials?
Biennials feature some of the most striking and unusual flowers available in all types of plant, but there is a drawback that’s not for everyone.
Here’s everything you need to know about biennials, including how to get the best out of them, and some of the most beautiful flowering biennial plants you can grow.
What Are Biennial Plants, and Why Should You Grow Them in Your Garden?
Biennial plants generally take two years to complete their life cycle. Like with annuals, you’ll need to collect the seeds or take cuttings in order to have more biennial plants before they die, but they do last longer than annuals.
Biennial plants will not grow flowers in their first year. This is because the plant spends the first year producing everything it needs to survive, including the roots, the foliage, and the stems.
It’s only in the second year that biennial plants flower, setting seed before it dies.
Some biennials can take longer than two years to grow and die, while, if the conditions are completely wrong, they may go through an accelerated period of growth, completing their cycle within three months.
It’s worth noting that there are much fewer biennial plants, when you compare them to perennials or even annuals.
So why should you grow them in the first place? They are worth the wait.
While they are a bigger challenge than annuals and some perennials to grow, they have some of the most beautiful flowers you can grow yourself.
Largely, they flower for much longer periods than both annuals and perennials, and they produce a lot of seed which ensures a good amount of flowers in new plants, too.
How to Make Sure Biennial Plants Thrive
It’s worth knowing that some biennial plants need cold weather in their second year in order to flower, so choose carefully if you live somewhere that doesn’t get a lot of cold spells.
These cold snaps signal to the plant that it’s time to start the growth to produce flowers, and without it, they may not produce any flowers, just more foliage.
Biennials are very easy to grow from seed. You can start them off on a sunny windowsill or in a greenhouse, or, if the type of plant you’re growing is hardy enough, you can sow them directly into the soil.
Most biennial plants are sown in summer. This allows them to develop the growth they require during their first year, to be able to flower during their second year.
With the young plants, you’ll need to be careful you don’t overwater them, as juvenile plants are vulnerable to drowning in large amounts of water, especially when the stems are much more delicate.
If you live somewhere that gets cold winters, and you pick tender biennials, you’ll need to bring them indoors in the winter months.
You could also use horticultural fleece to protect them from freezing temperatures, but this doesn’t always work.
You can also buy them as plug plants in the spring months, if you prefer.
A good rule of thumb with biennials is to give them the same care that you would if you were expecting them to flower that year.
Make sure you give them the right conditions that the specific type of plant needs, including the right amount of light, water, type of soil, and fertilizer.
Biennial Plants You Should Grow At Least Once
There are many types of biennials to choose from. Here’s just some of the most fabulous biennial plants that you should grow in your own garden, at least once.
While many of us are familiar with the purple or blue columbine, Aquilegia ‘Florida’ is a fabulous bicolored type which produces flowers in white and rays of yellow.
Most Aquilegia varieties have nodding heads that are too heavy for the plant to hold upright, but ‘Florida’ features blooms which open towards the sky.
Columbines are a favorite plant of pollinators, which helps boost the overall health of your garden’s ecosystem.
‘Florida’ will get to a maximum height of 70cm, producing a plethora of colors. If you want to grow them from seed, you should start them off in summer, allowing them to grow enough foliage, stems, and roots for a truly inspiring display in the following summer.
Columbines like moist, well-draining soil, in either full sunlight or partial shade.
Perfect for the front of a border, Dianthus ‘Superbus’ is a very unusual type of pinks, known for its fringed, lace-like flowers, providing an abundance of perfume into your garden.
They are also suited for containers, providing a wealth of color and unique form to any planting scheme.
Sow them somewhere sheltered in spring, under a very thin layer of compost, and they will flower in the height of summer in the following year.
For the most blooms possible, allow the plants full sunlight, where they’ll get to a maximum height of 45cm.
Digitalis purpurea ‘Sutton’s Apricot’
While most foxgloves are known for being a deep pink or a rich purple, ‘Sutton’s Apricot’ is a very fanciful variety, producing rays of clustered flowers in soft pinks, pale oranges and lilacs.
Like the vast majority of Digitalis, ‘Sutton’s Apricot’ does best in dappled shade, where it will get to an eventual height of 4 feet.
It also helps that these blooms will self-seed regularly. Once they have finished flowering, in the following spring you’ll notice lots of baby foxgloves peppered around the original plant, which you can dig up, and transfer into pots until they are big enough to be planted out again.
It’s worth mentioning – if you’re unfamiliar with foxgloves – that these gorgeous plants are very poisonous, so keep them away from pets or children. They also attract a lot of bees into the garden, too.
Echium vulgare ‘Blue Bedder’
If you’d like a biennial that’s sure to attract plenty of bees into your garden, you can’t go wrong with Echium vulgare, or ‘Blue Bedder’.
While most people grow it as an annual, this is a biennial plant which has a compact growth habit, producing vigorous carpets of true-blue flowers.
Each flower produces a wealth of nectar that butterflies and bees alike will gravitate towards.
It’s worth noting that they don’t have a great cold tolerance, so you’ll need to keep them somewhere sheltered in full sunlight, where the soil is able to drain well.
Sow seeds in the last few weeks of summer outdoors, and then overwinter the seedlings, so they will flower in the following year.
Nigella damascena ‘Miss Jekyll Alba’
Nigella (see also Love-In-A-Mist Grow Guide) is usually treated as an annual plant, but when sown in late summer, it will produce much better flowers the following year, for much longer.
‘Miss Jekyll Alba’ is a very striking variety, featuring the characteristic airy foliage, and bright white flowers, featuring a splash of royal purple in the center.
The plant itself will reach just under 50cm at its full height, and makes a perfect ground cover plant. To get the best out of Nigella, plant it in full sunlight in a sheltered area, in well-draining soil.