“Essential Biennials: My Must-Grow Flowers”

Last week, on a bright sunny day, I found great joy in planting white Canterbury bells (Campanula medium ‘Alba’) in the cut-flower garden. Nearly a hundred hearty saplings, all nurtured from a single packet of seeds sown back in June, were carefully teased out into a cell tray for their further growth and development over the summer. Originating from France and Italy, this robust biennial, a beloved fixture of country gardens, possesses a long-standing history dating back several centuries.

The plants, with their robust towering stems, are adorned with abundant clusters of large bell-shaped blooms, the colour of which can range from deep blue and pink to a pristine snow white, depending on the variety. The common name, dating back to medieval times, is thought to have been inspired by the flower’s resemblance to the small bells that Canterbury pilgrims attached to their horses.

Across the waters in the USA, Canterbury bells were among the initial imported flower species to be nurtured in colonial America. Thomas Jefferson, the former American president who was also an avid gardener, famously grew vast quantities of Canterbury bells at his Monticello residence in Virginia. The renowned English garden designer and writer Gertrude Jekyll was also an advocate of these flowers, however, she expressed a distinct preference for the elegant simplicity of single-flowered types, deliberately bypassing the more ostentatious double-flowered variants, which she viewed as “confused and disfigured”.

The hardy, early bloomers are essential plants to my garden, Sweet William, also known as Dianthus barbatus, is among the few biennials I’d always want in my garden. This easy-to-grow, fragrant biennial also makes an impressive cut flower, brilliantly standing the test of shifting gardening trends. The plant is sturdy, blooms over an extended period, possesses remarkable resilience, and is adaptable to various growing settings as long as sufficient sunshine is provided. It forms a lush, semi-evergreen, low foliage cover, sprouting its vibrant, edible, pollinator-friendly, and scented flowers in dense clusters during the late May-June period. You can typically find trays of these young plants in garden centres around this time of year, and if they’re planted this month, they’ll surely bloom by early next summer. There’s a myriad of hued varieties to choose from such as plum, white, red, and pink with some even having a bicolor aspect, all of which can be effortlessly cultivated from seeds. Just like the Canterbury bells, Sweet William also easily self-propagates in favourable conditions, yielding seedlings that can conveniently be relocated to their final growing spots in the ensuing weeks. It’s also straightforward to manually collect large quantities of mature seeds from mature plants during this season.

Another biennial that’s indispensable to my garden is the foxglove, traditionally referred to as ‘fairy thimbles’. Rather than the wild type, Digitalis purpurea with its towering, elegant spires of dark pink-purple flowers, I prefer the white-flowered Digitalis ‘Alba’ and Digitalis ‘Sutton’s Apricot’. As with the Canterbury bells and Sweet William, I typically sow the foxglove seeds in the late spring or early summer and gingerly move the sprouts into a cell tray before finally planting them into their permanent positions around this time, ensuring they’re properly watered. Over time, these young plants slowly develop strong base rosettes of leaves from which their majestic blossoms gracefully appear as summer comes around the following year.

Foxgloves are known to self-seed abundantly if left unattended, however, to maintain their pastel hues, it is preferable to sow them using purchased seeds. These plants prefer well-drained, humus-rich soil and thrive in sunlight or light shade. Their germination is initiated by light, and so are frequently noticed in spots where forests have been freshly cut down. Despite their known toxicity, many opt for including them in their gardens. Our gardens would certainly be lacking if we shied away from all poisonous species.

Planting wallflowers (Erysimum cheiri), another robust biennial and a staple in cottage gardens, is ideal during the early autumn. My botanic education in Glasnevin involved gardening internships across various Dublin parks, where we populated the city’s public flowerbeds with these traditional spring bedding plants, delivered bare-rooted and colourfully wrapped in moist newspaper. Their vibrant hues range from acid yellow to blood-red and they can be found in several garden centres for purchase around this time of the year. Although they may not be as popular as before, there’s been a noticeable resurgence, likely owing to longing for a simpler time and the introduction of new variants sporting more muted tones, doubled blooms and extended flowering periods.

Wallflowers, cherished for their vivid colours and distinct scent, compliment spring-flowering bulbs beautifully and can also be used in flower arrangements. It’s important to remember that their name, ‘wall gilliflower’, alludes to their fondness for full sunlight and loose, rocky soil, where they will self-seed if they’re content. According to legend, the seeds of this plant were introduced to England via limestone imported by William the Conqueror in the 11th century. In Ireland, wallflowers, also known as ‘lus an bhalla’, can frequently be noticed rooting themselves into the stone walls of dilapidated structures, after becoming a naturalised species.

The sturdy biennial, commonly referred to as honesty or Lunaria annua, flowers concurrently with spring-flowering bulbs like tulips, narcissus, allium, and fritillaria. Its tall, delicate flower stems provide an excellent counterbalance to the more structured blooms of these bulbous species. Ideally, it should be planted in a spot with ample sunlight or slight shade, in a cool, damp yet well-draining soil. The plant tends to reseed freely when conditions are favourable. Those who already have it should be on the lookout for new seedlings to transplant or shift to their permanent locations in the garden. Saving the ripe seeds for future planting is also advisable. The species’ deep purple-pink blossoms are quite attractive, as are the violet-blue flowers of Lunaria ‘Corfu Blue’. My personal favourite, however, is the white-bloomed Lunaria annua ‘Alba’. All variants yield the ornamental, disc-shaped ‘silver dollar’ or ‘silver penny’ seed heads that have made the species famous.

Gardening activities this week
Now is the right time for the summer pruning of established cordon-trained apple trees and fan-trained fruit plants in addition to gooseberry bushes, currant bushes, and summer-fruiting raspberries. This promotes balanced, productive vegetation and an abundance of fruit-bearing branches for the next year. For more information, visit rhs.org.uk.

From the end of August to the beginning of September, it’s also recommended to trim back garden hedges like beech, hornbeam, Thuja and Leylandii.

Upcoming events
On the 30th of August to the 1st of September, between 2pm-6pm, the Festival of Flowers will be happening. It will commemorate the 100th anniversary of St Oliver Plunkett Church on Sea Road, Haggardstown, Blackrock, Co Louth, with the postcode A91 WD56. The festival is coordinated by Chelsea gold medal-winning garden designer Paul Martin and will include splendid showcases by floral designers such as Jenny Murphy (also a Chelsea gold medal winner), Caroline Slevin, Blooms and Strandfield. Everyone is invited.

On Saturday, 31st of August from 2.30pm to 4.30pm, the Howth & Sutton Horticultural Autumn Show and Plant Sale will take place at St Nessan’s Community School, Baldoyle, Dublin, D13 F6N3. New exhibitors are most welcome. For more information, check hshs.ie.

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