How to Grow Ranunculus from Corms

Ranunculus are one of the most breathtaking spring flowers — lush, rose-like blooms in soft pastels and bold jewel tones that look straight out of a fairytale. They’re also one of our favorite crops here at Two Kays Flower Farm, because when they’re grown correctly, they produce long, strong stems and an incredible abundance of blooms.

If you picked up a bag of ranunculus corms from our spring pop-up, this guide will walk you through everything you need to know to grow healthy, vibrant ranunculus right in your own garden.

What Are Ranunculus Corms?

Ranunculus grow from corms, which look a bit like tiny dried octopuses or claws. These are not seeds — they’re a storage organ packed with the energy your plant needs to grow. When dry, they’re dormant. When rehydrated and planted, they come back to life.

Step 1: Soak Your Ranunculus Corms

Before planting, ranunculus corms must be soaked to rehydrate them.

Place your corms in a bowl of room-temperature water and let them soak for 3–4 hours. During this time, they will plump up and swell — this tells you they’re waking up and ready to grow.

Do not soak longer than 4 hours. Over-soaking can cause rot.

Step 2: Optional — Pre-Sprouting for Faster Blooms

Professional flower farmers often pre-sprout ranunculus to get a head start.

After soaking:

1. Place the corms in a shallow tray or container.

2. Cover them completely with slightly damp potting soil.

3. Keep them cool and moist (50–55°F) and dark for 10–14 days.

4. Keep checking on them during the 10-14 days and remove any that get moldy.

   
   

You’ll start to see tiny white roots and a small green or pink growth point. Once sprouted, they’re ready to plant outside or into containers.

Step 3: When to Plant Ranunculus

Ranunculus love cool weather. In Montana and similar climates, plant them:

• Early spring, once you know the ground will no longer freeze-often about a month prior to your last spring frost

• Or in fall if you have mild winters and protection (not for folks here in Montana)

  
  

They tolerate light frost (we always suggest caution and providing frost cloth if the nights are too chilly) and actually perform best when nights are cool.

Step 4: How to Plant Ranunculus

Plant your soaked or sprouted corms:

• Claws facing down

• About 1 inch deep

• Spaced 6–9 inches apart

  
  

Choose a spot with:

• Full sun

• Well-draining soil

  
  

Ranunculus hate wet feet. If your soil stays soggy, add compost or plant them in raised beds or containers.

Step 5: Watering and Care

Water well after planting, then keep soil lightly moist. Once growth starts, avoid overwatering — soggy soil can cause corms to rot.

As the plants grow:

• Keep weeds down

• Protect from slugs

• Support with light netting if grown in windy areas

When Will They Bloom?

Ranunculus typically bloom 90–120 days after planting. In our Montana climate, that means glorious blooms in late spring and early summer.

The cooler the weather, the longer they will bloom — often for 6–8 weeks.

Harvesting (or Enjoying in the Garden)

For the longest vase life, cut ranunculus when the blooms feel like a soft marshmallow — not tight like a bud, but not fully open either.

Or simply enjoy them in your garden as one of spring’s most beautiful flowers.

Happy planting — and we can’t wait to see what you grow.