How to Grow Larkspur
from Seed in the UK
A complete guide for beginners — sowing, growing and enjoying one of the cottage garden's most bewitching flowers
Larkspur is one of those flowers that makes a cottage garden feel truly complete. With its tall, elegant spires in shades of violet, blue, pink, white and deepest plum, it has a painterly quality — as though it belongs in a watercolour rather than an actual garden. The good news? It's wonderfully straightforward to grow, costs very little, and once you've grown it, you'll wonder how you ever managed without it.
This guide will walk you through everything you need to know, from sowing your first seeds to cutting great armfuls for the vase. Don't be daunted — larkspur is a friend to beginners and a joy to experienced gardeners alike.
Quick Facts at a Glance
Plant Type
Hardy Annual
Sowing Time
Sept–Oct or Feb–Apr
Flowering Months
June – August
Position
Full sun to part shade
Eventual Height
60–120cm
Difficulty Rating
2 out of 5 — Easy
When & How to Sow
Larkspur is a hardy annual, which means it can tolerate frost — and actually prefers a cold spell to help it germinate well. This makes it ideal for direct sowing outdoors, and it really doesn't like having its roots disturbed, so sowing where it is to flower is absolutely the right approach.
You have two ideal sowing windows in the UK:
Autumn Sowing (September – October) — Recommended
Sowing in autumn gives larkspur the cold stratification it loves. Seeds overwinter in the ground, germinate earlier in spring, and produce bigger, stronger plants that flower earlier and for longer. This is the method cottage gardeners have used for generations, and it really does give the best results.
Spring Sowing (February – April)
If you miss the autumn window, don't worry. Sow in early spring — February to April works well — ideally giving the seeds a few cold nights to help trigger germination. You can also pop the seed packet in the fridge for a week before sowing to mimic this cold period.
Larkspur seeds sown directly into a well-prepared bed — simple and satisfying.
Step by step:
-
Choose your spot. Larkspur likes a sunny or lightly shaded position with well-drained soil. It dislikes heavy, waterlogged ground — if your soil is clay-heavy, work in some grit or compost before sowing.
-
Prepare the soil. Rake the area to a fine tilth (a crumbly, even texture). Remove any large stones or debris. Larkspur doesn't need rich soil — in fact, too much fertility can encourage leafy growth at the expense of flowers.
-
Sow thinly and directly. Scatter seeds thinly across the surface or sow in shallow drills around 6mm deep. Try not to sow too densely — overcrowding leads to weaker plants and encourages mildew.
-
Label clearly. This sounds obvious, but larkspur seedlings look much like weeds when they first emerge — a label will save you accidentally pulling them up!
-
Water gently. Use a watering can with a fine rose to avoid washing seeds away. Then leave them to it — larkspur germinates best with minimal fuss.
-
Thin the seedlings. Once they're a few centimetres tall and have their first true leaves, thin to around 20–30cm apart. It feels drastic, but the remaining plants will be all the better for it. You can compost the thinnings rather than transplanting, as larkspur really doesn't like being moved.
Beginner's Reassurance
Don't worry if germination feels slow — larkspur can take two to four weeks, sometimes longer in cold conditions. As long as the soil doesn't dry out completely, they'll come. Patience is rewarded beautifully here.
Growing On Tips
Once your larkspur seedlings are established, they're pleasingly low-maintenance. Here's what to keep an eye on through the growing season.
Watering
Water young seedlings regularly, especially during dry spells in spring. Once established, larkspur is reasonably drought-tolerant — water during prolonged dry periods but avoid keeping the soil constantly wet, which can lead to rot.
Feeding
Larkspur generally doesn't need feeding — it can actually perform better in leaner soils. If your soil is very poor, a single application of a balanced general fertiliser in spring will be more than enough. Avoid high-nitrogen feeds, which push leaves at the expense of flowers.
Support
Taller varieties — particularly those over 90cm — may benefit from a few twigs or bamboo canes pushed in around them for support, especially in more exposed gardens. This is worth doing early before the plants get too tall. Shorter varieties are usually self-supporting in a sheltered spot.
Deadheading
Larkspur doesn't benefit from deadheading in the same way as some other flowers — it blooms on a central spike and then sets seed. If you want a longer display, let some plants seed naturally and cut others for the vase. You can allow plants to self-seed for a colony next year.
Self-Seeding Tip
One of larkspur's loveliest qualities is that it self-seeds freely. If you leave a few plants to set seed and drop naturally, you'll find a colony establishing itself over years — meaning you may barely need to sow at all. Just allow the seed heads to ripen and shake on the ground before you clear spent plants.
Common Problems & How to Fix Them
Larkspur is generally a tough, trouble-free plant, but here are the issues you're most likely to encounter and how to deal with them calmly.
| Problem | Likely Cause | What to Do |
|---|---|---|
| Poor germination | Seeds too warm, too old, or sown too deep | Sow shallowly (6mm max), ensure seeds are fresh, and try a cold spell before sowing — either autumn sowing or a week in the fridge first. |
| Powdery mildew on leaves | Poor air circulation, overcrowding, dry at roots | Thin plants to improve airflow, water at the base rather than overhead, and remove affected leaves. Mildew usually appears late in the season and rarely ruins the display entirely. |
| Slugs & snails | Moist conditions, young seedlings | Young seedlings are most vulnerable. Use organic slug pellets, copper tape, or set beer traps around the emerging plants. Once established, larkspur is less susceptible. |
| Tall, floppy plants | Too much shade, too much nitrogen, insufficient support | Choose a sunnier position next time, avoid rich feeds, and stake taller varieties early in the season with twigs or canes. |
| Plants not flowering | Too much shade, overcrowding, or late sowing | Ensure plants receive enough sun, thin to the recommended spacing, and try earlier sowing — either autumn or early spring — next year. |
| Sparse or small blooms | Overcrowding or over-feeding | Thin more aggressively (30cm between plants) and avoid feeding unless soil is very poor. Lean conditions produce the best flowering. |
Important Note
All parts of the larkspur plant are toxic if ingested, so do wash your hands after handling and keep out of reach of young children and pets. This is worth knowing, but needn't put you off growing it — it's perfectly safe to grow and handle with simple care.
When to Expect Flowers
If you sow in autumn, you can expect larkspur to begin flowering from late May or June — sometimes even a little earlier in a mild year. Spring-sown plants will typically flower from late June through to August.
The display usually lasts around four to six weeks per plant, though a bed with a mix of autumn and spring-sown plants can give you a longer combined season. Once flowering is over, plants set seed and die — this is normal, and is just the signal to let them self-seed or collect seeds for next year.
Succession Sowing
For the longest possible display, sow in both autumn and early spring. The two batches will flower at slightly different times, giving you a more extended season of colour and cutting material.
Cutting & Drying
Larkspur is one of the finest cut flowers a cottage garden can produce, and it dries beautifully too — making it a true double-duty plant for anyone who loves bringing the garden indoors.
For cutting fresh
Cut larkspur spires when around a third to half of the flowers on the stem are open — the remaining buds will continue to open in the vase, giving you days of enjoyment. Cut early in the morning when the stems are well hydrated, and place immediately into deep, cool water. Change the water every couple of days and snip the ends at an angle to extend vase life. You can expect fresh larkspur to last around five to eight days in a good condition.
Larkspur dries to perfection, retaining its colour beautifully for months.
For drying
Larkspur is genuinely one of the best flowers for drying — it holds its colour exceptionally well, with blues and purples in particular remaining vivid for months. Cut stems when most of the flowers on the spike are open but before they start to drop. Strip the lower leaves, bundle in small groups of five to ten stems, and hang upside down in a warm, dry, well-ventilated space away from direct sunlight. They'll be ready in two to three weeks.
Perfect For
Dried larkspur is wonderful in wreaths, dried flower arrangements, botanical frames, and as a pressed flower. It's also a popular choice for wedding flowers and handmade gifts — and because you've grown it yourself, it carries an extra layer of meaning.
Cutting Garden Tip
Regular cutting actually encourages larkspur to produce more side shoots and prolongs flowering. Don't be shy with the scissors — the more you cut, the more you get. Think of it as doing the plant a favour.
Ready to grow your first larkspur?
We think once you grow larkspur, it becomes a permanent fixture in your garden — and we'd love to help you get started. Our larkspur seeds are carefully selected for the cottage garden, with a mix of beautiful colours that look wonderful together and cut like a dream. Whether you're filling a border, building a cutting garden, or simply wanting to add a little magic to a sunny corner, this is a seed worth sowing.
Shop Our Larkspur Seeds