
1. They Fill the Spring Gap Like Nothing Else
After the bulbs fade and before the annuals really kick in, there’s often an awkward lull in the garden—a floral no-man’s land. Enter the biennials: wallflowers, foxgloves, sweet rocket, and the rest. Sown in summer, they bulk up over autumn and winter, then leap into flower when spring arrives, just when you need them most.
They’re your bridge between seasons, a kindly bunch that bring colour and structure to an otherwise quiet time.
2. They’re Tough as Old Boots
Most biennials are hardy by nature. They’re the sort of plants that scoff at frost and don’t need mollycoddling. Sown in June or July, they establish themselves in warm soil, grow sturdy before the cold sets in, and overwinter without complaint. Come March, they’re up and away, blooming like they’ve been waiting all winter to show off.
In my experience, a well-grown biennial is more resilient than many perennials. They’ve got grit.
3. Slugs Leave Them Be
This is not an exact science, but I swear blind that slugs are less interested in biennials. Perhaps they’re too leathery by the time the molluscs get to them, or maybe the slugs are off tormenting your dahlias and cosmos. Whatever the reason, sowing biennials feels like planting with a bit more peace of mind.
4. They’re Absolute Bargains

A packet of foxglove or wallflower seed costs a couple of quid and will give you dozens of plants. Compare that to buying plugs or established plants in the spring (when garden centres charge like wounded bulls), and you’ll see why summer sowing is so satisfying.
Sow them in trays or modules, pot them on when they’re big enough, and plant them out in autumn. It’s easy, economical, and oddly therapeutic.
5. They’re Brilliant for Pollinators
Biennials tend to be nectar-rich and pollinator-friendly, making them a boon for bees, butterflies, and other beneficial visitors. Early in the season, when little else is about, your garden will be buzzing with activity.
Sweet rocket, in particular, gets a gold star from the bees. It’s like a corner café for pollinators just emerging from winter.
6. They Add Height, Drama, and Romance

Many biennials are tall and elegant, perfect for adding vertical interest to your beds and borders. Think of the spires of foxgloves rising through frothy forget-me-nots, or clumps of sweet Williams with their candy-coloured heads nodding in the breeze.
They lend a bit of old-fashioned charm, the sort of thing you see in cottage gardens or the pages of a Miss Marple novel.
7. You’ll Feel Gloriously Smug Come Spring
There’s a particular smugness reserved for those who plan ahead in the garden. While others are scouring the shops for bedding plants in April, you’ll be wandering around your patch, hands in pockets, admiring your well-established, homegrown beauties.
You sowed them last summer, forgot about them for a bit, and now they’re putting on the show of their lives. All for the price of a posh coffee and a bit of potting compost.
In Conclusion…

Sowing biennials in June and July might not come with the instant gratification of a quick-growing annual, but it’s one of the cleverest, most rewarding things you can do as a flower grower. It’s a small act of faith in next year’s garden, and one that always pays off.
So go on—dig out your seed packets, water your trays, and give the biennials their due. Your spring self will thank you, and so will the bees.
You can see our Biennial collection here. (Including a discounted bundle)
Best wishes
Higgers and Flash.
