How to Sow Larkspur Seeds for Stunning Cut Flowers

Larkspur (Delphinium Consolida) is one of those flowers that quietly blossoms in the corner when no one is looking. Tall, elegant spires covered in clouds of blooms — blue, pink, lavender, or white — they aren't afocal flower but the best a supporting act you can grow.

They’re also a flower I get endless questions about, because while they look effortless once established, sowing larkspur seeds can be a bit of a headache if you don’t know their quirks.

I’ll be honest: larkspur isn’t the easiest flower to germinate - unless you know how! and once you crack the code, they’re one of the most rewarding cut flowers you can grow — and they even have a secret bonus: they’re a zero-waste flower.

When to Sow Larkspur Seeds

You’ve got two main windows:

• Autumn (Sep–Oct): Sow direct into the soil or in deep modules. Plants overwinter, giving you taller stems and earlier flowers the following year.

• Early Spring (Feb–Apr): Sow again for a later flush of flowers. Even if you missed autumn, spring sowings still perform beautifully.

The golden rule is cool conditions — larkspur seeds hate the heat. If you try to sow in summer warmth, you’ll be fighting nature.

Why Cold Stratification is Essential

Here’s the bit most people miss: larkspur seeds often need a period of cold to break dormancy. In the wild, that’s what winter does. In our seed trays, we need to recreate it.

I usually pop my larkspur seed packets into the fridge for 2–4 weeks before sowing. Around 5°C is ideal, and better still take then in and out of the fridge a few times during the day to mimic mother nature - cold at night and warmer during the day! Or, you can sow in autumn and let the natural frosts do the work for you. Without that cold spell, germination can be patchy or non-existent.

How to Sow Larkspur

• Sow onto the soil surface and cover very lightly with some vermiculite — larkspur seeds need some light to germinate.

• Keep temperatures cool: 10–15°C is the sweet spot.

Germination can take 14–28 days and it’s often erratic, so don’t give up too quickly. I’ve had trays where half the seedlings came up after two weeks and the rest took another fortnight. They need fluctuations in temperature to break their dormancy so patience is key.

Growing On

Once seedlings are up, thin them out to their own cells or pots and grow them on in a greenhouse or cold frame. They don't require any heat. Don't be tempted to put them on the windowsill - they don't need it and they won't thrive - they will grow tall, leggy and weak. But what you are looking for is root growth during the winter - which is all happening underground. and if they develop good roots they will shoot up in spring time much healthier.

In early spring they can be planted out but they do much better wit a little protection in the form of a low hoop, or you may have a polytunnel or greenhouse.

Larkspur as a Cut Flower

For cutting, harvest when the bottom third of florets on a stem are open. That’s the stage where they’ll last longest in a vase — usually 7–10 days if conditioned properly.

But here’s the thing about larkspur: they go over quickly. Blink, and you’ve missed the perfect cutting window. That used to frustrate me — until I realised larkspur are actually a zero-waste flower.

Drying Larkspur: The Zero-Waste Flower

If you miss them fresh, don’t panic. Larkspur are one of the easiest flowers to dry. Simply cut stems when the flowers are fully open and hang them upside down in a dark, well-ventilated space. The colour holds beautifully, especially the blues and purples.

This means nothing ever needs to go on the compost heap. If a stem is too short, too late, or too floppy for a bouquet, it still has value dried. I often tuck dried larkspur into wreaths, dried flower bunches, or even just keep a big jug of them in the studio. They’re the definition of zero waste — every stem finds a home.

Larkspur isn’t a “sow and forget” flower. They demand cool conditions, patience, and a bit of planning — but in return, they give you armfuls of tall, elegant stems, plus the bonus of a dried flower that lasts all year.

If you’ve struggled before, don’t be put off. Once you understand their quirks — cold stratification, careful sowing, and the joy of drying — larkspur will quickly become one of your most treasured crops.

Ready to give it a go? Join my Grow Along — I’ll show you every step, from sowing right through to armfuls of blooms.

Explore our Larkspur Seed Collection