Sow Easy!

Posted by

Ali Barwani

18 July 2025

On 18 July 2025

Sow Easy!

How have you been coping with the recent soaring temperatures? While it’s easy to flake out with this heat, even giving vital watering a miss, it is a mistake to think that the gardening year is over. With the arrival of cooler weather and the promise of rain, now is the time to set the stage for next year. Visting your local garden centre and seeing so many beautiful plants in full flower is always tempting. Who doesn’t enjoy that rush from purchasing a pot of instant colour? I don’t see any hands up! But I want to remind you that there is pleasure to be gained in playing a longer game; by sowing biennial seeds now you can win your prize of swath es of flowers next year.

So, biennial flowers can make a valuable contribution to the garden, but what exactly are they? You will already be familiar with some of them: angelicas, Brompton stock, Canterbury bells, echiums, forget-me-nots, foxgloves, honesty, teasels, biennial verbascums, or honey-scented bedding wallflowers. Biennials are flowering plants that complete their life cycle in two years. During the first year, they typically form low-growing rosettes of foliage, channelling energy into developing their roots, leaves and stems. These extensive root systems, often a tap root, mine the soil, extracting water and nutrients to promote this growth. Following a period of dormancy over the winter months, the leafy rosettes begin to elongate and flower in their second year. Once they have bloomed and set seeds, the plants die. Many short-lived perennials are treated like biennials by gardeners and sown every year, for example, hollyhocks, sweet rocket and sweet William. In fact, some perform better when grown as biennials, as their flowering tends to decline in subsequent years.

Growing biennials from seed offers several advantages, let’s look at a few. It’s cost-effective. A packet of mixed foxglove seeds with an average packet content of 4600 seeds can be purchased for £2.99, whereas a single

foxglove plant in a 1 litre pot might cost £6.99. Biennials constantly renew themselves, moving around the garden by broadcasting their seeds, keeping your garden feeling fresh and lively. Many biennials are British native wildflowers, making them good at attracting insect pollinators and pest-predators to your garden. Biennials are low-maintenance and easy to grow from seed, with many being suitable for direct sowing. Flowering in their second year, they provide a burst of colour in the garden just when it’s most needed, as the tulips and other spring flowers are fading. Most make good cut flowers, too. They are useful for fraying areas that look too formal in the garden, for example softening the edges of paths and driveways. There are more varieties of these cottage garden favourites available as seeds than garden centres can stock as pot grown plants, so you get more choice. I was reminded of this when visiting the RHS Chelsea Flower Show this year and admiring a stand of diverse foxglove species and cultivars in the Great Pavilion. Biennials are a great way of adding much needed height and colour to beds and borders. Hollyhocks, mulleins, and common foxgloves can shoot flower spires up to 2m high, stealing the show in summer. Finally, their overwintering rosettes of foliage make great ground cover, helping protect the soil from erosion, nutrient loss, and weed growth.

Act now. July is a good month to sow the seeds of biennial plants that will bloom next summer. The warm weather facilitates rapid germination, and the plants have ample time to grow and overwinter before flowering. Seeds can either be sown directly where you want them to flower next year or into seed trays, remembering to water your seedlings regularly during dry periods. If you start them off in trays then the seedlings will need potting up, before being planted out in autumn or the following spring. Ensure your young plants have enough space to grow and develop strong root systems by thinning out seedlings or spacing out pot grown plants. It is always worth keeping a few potted seedlings to plug any gaps that appear in the garden during spring and summer.

In conclusion, growing biennial flowers from seed is a rewarding and economical way to fill your garden with height and colour. With a bit of planning and care, you can enjoy a stunning display of blooms next year. So why not try sowing some biennial seeds in your garden this weekend?