How to Grow French Ranunculus in the UK- Planting, Care & Cutting Tips

If you’ve ever spotted armfuls of ranunculus at a wedding or florist and wondered how to grow them yourself, you’re in the right place. Ranunculus are one of the most profitable and show-stopping cut flowers you can grow — but FRENCH ranunculus take things to a whole new level.

These florist-grade varieties are bred for larger blooms, stronger stems, incredible vase life, and the most extraordinary colour mixes — from champagne and blush tones to smoky apricots, plums, and velvety jewel shades. Even better, they’re more heat-tolerant, so plants keep setting buds a little longer into spring instead of shutting down at the first warm spell.

Ready to try them? Here’s exactly how to grow ranunculus corms in the UK for cutting, arranging, and SWOONING over.

When to Plant Ranunculus Corms in the UK (Spring vs Autumn)

Ranunculus are a cool-season flower, thriving in temperatures between 10–15°C.

• Autumn planting (Oct–Nov): Gives the earliest flowers and strongest stems. Need protection under fleece, a low tunnel, greenhouse, or polytunnel.

• Spring planting (Feb–Mar): Ideal if you don’t have cover or live in a colder area. The flowers will come slightly later, but you’ll still get armfuls.

  
  

For the longest season, succession plant — one batch in autumn and another in spring.

How to Prepare Ranunculus Corms

Step 1: Soaking

Soak corms in room-temperature water for 3–4 hours to rehydrate them. The water needs to be oxygenated to avoid rot. Professional growers often use an aquarium oxygenator to keep water moving. If that’s not practical (for most of us it isn’t!), just refresh the oxygen by spraying or pouring fresh jets of water into the bucket every 20 minutes or so during the soak. You can use a jet water tap or a hoze pipe - watch the grow along on You Tube

After soaking, you’ll notice a visible change in the corms: they’ll look bigger, plumper, and firm to the touch, a world away from the small, dry, shrivelled claws you started with. That’s when you know they’re ready for pre-sprouting.

Step 2: Pre-sprouting

Once soaked, remove corms from the water and place them into shallow trays of damp compost, vermiculite, perlite, or a mix — it doesn’t matter which medium you choose they wont be in there for very long and the medium is basically just keeping the corms moist to encourage sprouting. Keep them at around 10–15°C for 10–14 days until tiny roots & shoots appear. Tray can be stacked on top of each other to save space as they do not require any light to start sprouting.

Why Bother?

Although you can skip soaking and pre-sprouting, it’s highly advisable. Prepped corms are less likely to rot and give much stronger, faster results — so the little bit of extra effort pays you back in buckets of flowers - after all you've spend the money and time getting this far it makes sense to give them the best start.

How to Grow Ranunculus Outdoors and in Pots

After about two weeks you’ll start to see signs of life — tiny white rootlets pushing from the base of the corms and small leaf buds forming on top. If you’ve left your corms on the surface of the soil while pre-sprouting, this stage is easy to spot. At this point, you can either transplant them into individual cell trays or pots to grow on a little longer, or plant them directly into beds or large pots where they’ll stay for the season.

How to Grow Ranunculus Outdoors and in Pots

Plant corms 5cm deep and 10–15cm apart, with the claws pointing down.

Ranunculus grow best where you can control the temperature. If you plant them outdoors with no protection, they’re likely to suffer in frosts. If you plant them in a greenhouse without ventilation, they’ll also stop flowering once spring temperatures climb too high.

 Vegetative Growth (roots + leaves)

• Ideal temperature: 10–15°C

• Ranunculus grow best in cool conditions. Rooting, leaf growth, and general plant development slow dramatically below 5°C and stress above 18°C.

Flower Initiation & Bud Formation

• Ranunculus initiate flower buds under cool, stable conditions.

• Critical range: 5–15°C at night, up to 18°C daytime.

• Extended periods above ~20°C stop further bud initiation — plants will push through any buds already formed but won’t keep producing. This is why spring heatwaves in the UK can cut the season short.

  

Here in the UK, spring is especially tricky — one week can be frosty, the next can hit 20°C. These swings have a huge effect on ranunculus. Success comes down to agility: being able to cover them quickly on cold nights, and uncover them just as fast on warm days.

👉 My best tip: plant them outside in the ground and use a removable low tunnel. Choose one where you can easily pull the plastic back or roll it up to ventilate. This way you can protect plants from frost, but also uncover them quickly if a hot spell arrives.

Growing in pots? Yes, you can — but choose large, deep containers and water consistently. Pots dry out much faster than beds, so don’t skip irrigation.

Ranunculus Growing Tips for Bigger Blooms

• Temperature: Keep them cool (10–15°C). French ranunculus handle heat better than others, giving you extra weeks of harvest but it's still important to keep them cool.

• Feeding: Use liquid seaweed or a balanced fertiliser every 2–3 weeks.

• Pinching: Removing weak early stems encourages stronger flowering.

• Mulch: Helps conserve soil moisture and keeps roots cool.

  
  

Harvesting Ranunculus for Cut Flowers

The “marshmallow stage”

• This is when the bud is fully coloured, soft and squishy (like a marshmallow), but not yet open.

• Cutting at this stage gives the longest vase life (up to 10+ days).

• Flowers harvested here will continue to open gradually in the vase.

  
  

Cutting later (partially open)

• Some growers prefer to let ranunculus open to the 2–3 petal stage (just starting to unfurl).

• This gives a more immediate, showy flower and is sometimes better for wedding/event work where flowers are used the same or next day.

• The trade-off is shorter vase life (closer to 5–7 days).

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For the longest vase life, cut when the blooms are at the “marshmallow stage”  and harvest with long stems, cutting just above a leaf node. French ranunculus can last 7–10 days in the vase, making them one of the most reliable cut flowers for florists and weddings.

Why French Ranunculus Are Worth Growing

• Heat tolerance → flower longer into spring.

• Unbeatable colour mixes → from soft pastels to rich velvet tones.

• Stronger stems + bigger blooms → bred for professional florist use.

• Luxury factor → one of the highest-value spring flowers for small farms and cutting gardens.

  
  

The Beauty of French Ranunculus

Ranunculus might look delicate, but once you understand their rhythm, they’re straightforward and incredibly rewarding to grow. French ranunculus, with their resilience and extraordinary palette, are the top choice for any grower who wants luxury flowers that last.

🎥 Watch my Ranunculus Grow Along video to see how to pre soak and pre sprout your corms .

🌱 Shop our full range of French Ranunculus corms