Pre-Sprouting Ranunculus & Anemone Corms
If you’re serious about growing ranunculus and anemones as a professional cut flower grower, pre-sprouting corms is one of those “aha” tasks. It’s a game-changer. It’s amazing. If you’re curious to learn about it, you’re in the right place!
In our last post, we covered the importance of pre-soaking corms: “You need to wake ‘em up by plumping ’em up”! Pre-soaking is a must-do step before pre-sprouting, as hydrated corms are key to initiating healthy growth. If you missed that post, you can catch up [here] or watch the video below!
At Sierra Flower Farm, we’re here to guide you through soaking your ranunculus and anemone corms—a crucial first step for healthy growth! Learn the how and why behind this process to set up your corms for success.
Once you’re up to speed, we’re ready for the second step toward a successful spring crop of ranunculus and anemones: pre-sprouting. Whether you’re one of the lucky ones with a greenhouse or high tunnel or a field-grown grower like me, pre-sprouting corms will set you up for beautiful, healthy blooms.
Now, let’s be real—a lot of growers get nervous when it comes to ranunculus and anemones. They’re a heftier investment than a pack of seeds, and the stakes are high! We choose to purchase fresh corms each season, especially as many popular varieties are patented and to avoid potential diseases. Much like tulips, corms can be an annual investment worth careful management.
The good news? These plants are resilient. They can thrive in colder climates with some upfront work and protection. Ranunculus and anemones are true spring beauties—photoperiod-sensitive, meaning they thrive in shorter daylight hours and struggle in the heat of summer, preferring daytime temps of 60-70°F with cooler nights.
One of the biggest challenges, as discussed in my last post, is avoiding root rot, as these flowers are especially susceptible to it. While pre-soaking is the first line of defense, pre-sprouting is another essential tool.
But what exactly is pre-sprouting?
Simply put, it’s allowing the corms to sprout in ideal, controlled conditions before planting them in their growing bed, instead of going straight from soaking to soil. It’s a simple concept but has its own process and specific steps, which we’ll dive into next.
Why Pre-sprout Corms?
Adding an extra step like pre-sprouting might seem like more work, but this is one of those times when a bit of effort upfront truly pays off.
Here are three key reasons why we chose to pre-sprout:
Saves Space: Pre-sprouting lets you weed out dud corms early, so you only plant healthy, viable ones. This saves bed space for thriving corms and avoids unproductive gaps. Plus, this step is especially useful if you're planning to save corms for next season, as older corms are more prone to rot.
Keeps Soil Healthy: By planting only the healthiest corms, you reduce the risk of introducing diseases or fungi to your soil. Pre-sprouting acts as a natural pre-screen, helping protect the entire crop from potential pathogens.
Gives a Jumpstart: Weather and soil conditions vary, especially in early spring, which can be tough on delicate crops like ranunculus and anemones. Pre-sprouting gives your corms a head start, allowing you to plant at the optimal time and avoid crop failure due to late freezes or early heatwaves. This head start can make the difference between an abundant harvest and no blooms at all.
With pre-sprouting, you have more control over the process, allowing you to adjust planting times to fit your schedule and the weather. Having a strong root system early on is crucial, especially for planting in cooler, wetter soil when conditions can be unpredictable.
Convinced? Great! Let’s dive into how to pre-sprout corms!
The Process of Pre-Sprouting Ranunculus & Anemone Corms
Pre-sprouting can be done in various ways with different substrates, so use what you have available and what you feel will yield the best results. Here’s what you’ll need:
Supplies for Pre-Sprouting:
Trays: Flat trays, 50-cell propagation trays, or air-pruning 72-cell trays (clean and sanitized).
Substrate: Quality potting soil, peat moss, vermiculite, or coco coir.
Pre-soaked corms (labeled after soaking).
Water: Room temperature or cold, never hot.
Cool, dark location: Aim for a spot between 40–50°F.
Optional: Fungicide, sticker labels, and a pencil.
Timing: When to Pre-Sprout Begin pre-sprouting immediately after soaking the corms. Avoid letting them dry out again but don’t keep them sitting in water for too long.
Optional Fungicide Treatment In the final 30–40 minutes of soaking, consider adding a biological fungicide, such as Actinovate, Rootshield, or Ailette, to the soak water. Once corms are placed in trays, you can apply the fungicide solution as a drench to help protect against pythium, fusarium, and other root rot infections. Pre-sprouting is especially valuable if you’re using saved corms, growing in a high-moisture area, or have had soil disease issues in the past.
Pre-Sprouting Steps
Step 1: Preparing the Substrate
Grab your chosen substrate (I’ve been loving Promix HP or Fox Farm’s Lucky Dog lately).
Put it in a bucket or deep tray and moisten it to feel like a wrung-out sponge—slightly on the drier side.
Tip: Add water gradually! It’s easier to add than take away, and we don’t want a soggy mess.
Fungicide Note: If you’re planning a fungicide drench, keep your substrate dry until the end so you can handle it more easily.
Step 2: Preparing the Trays
Fill your sanitized tray (or propagation tray) with a couple of inches of substrate.
Pro Tip: If you’re looking to invest, I love Bootstrap Farmer’s 50-cell and 72-cell trays. They keep any rotten corms contained and last season after season!
Use what you have, though! If your tray has big drainage holes, line it with something like a brown paper bag to keep the substrate in.
Step 3: Placing the Corms
Nestle the corms into the substrate, and make sure to label as you go! I rely on both plastic and sticker labels—pets, kids, and mischief all seem to have a thing for those plastic tags!
Place ranunculus corms “carrots down” and anemones with their pointy end down (think acorn shape).
Cover them with one to two inches of substrate.
Selecting a Pre-Sprouting Location for Ranunculus & Anemone Corms
Tuck your trays into an area where the temperature stays consistently between 40 and 50 degrees Fahrenheit. Keeping it closer to 40°F will encourage slower root growth, while 50°F promotes quicker root development. This range is ideal for nurturing strong, healthy roots in your corms.
If you’re lucky enough to have a basement or walk-in cooler, that’s perfect! For the rest of us, here are a few options that have worked over the years:
A deep chest freezer with an Inkbird thermometer
A commercial refrigerator
An unheated garage
Be sure your pre-sprouting spot stays above freezing and is safe from pests like rodents. And avoid any light exposure,whether artificial or natural. Why? You want the corms to focus solely on root growth—not on reaching for light.
Foliage isn’t our goal during pre-sprouting, especially for those in cooler climates. Early foliage might just get nipped back, which won’t ruin the crop but won’t benefit it either.
For us, stacking the trays in our unheated garage has worked wonders, as it helps the trays maintain consistent moisture levels without drying out too quickly.
Taking Care of Ranunculus & Anemone Corms During Pre-Sprouting
Wait. Walk away. Don’t check on those corms every hour—they’re fine! Check every other day or so, but remember: don’t kill them with love!
Water only when the soil feels dry. Don’t judge solely by the top layer—check where the corms are nestled. They don’t like being soggy, as it makes them prone to root rot. So, resist that watering can!
Unless your trays are exposed to open air, you likely won’t need to water them again during pre-sprouting. If they’re in a garage or similar space, using a dome lid can help retain moisture, but be sure to lift it occasionally to allow fresh air circulation.
We stack our trays on top of each other, which helps maintain moisture in our arid climate. We typically water weekly or biweekly.
After about two weeks (give or take), you should start to see white roots emerging from the corms. I wait until most roots reach about an inch long before moving forward. High-quality potting soil, especially one with perlite, helps with drainage and prevents waterlogging.
A note on anemone corms: they generally take longer to sprout than ranunculus, which makes sense given how hard they are. If the anemones are taking their time, don’t panic. They may need an extra week or two but will sprout, provided they aren’t molding or rotting.
As you check on your corms, remove any that appear mushy or rotten—they won’t grow and could infect the healthy ones.
Troubleshooting the Pre-sprouting of Ranunculus & Anemone Corms
If…
You are seeing excessive rot: Check your substrate to see if it’s too wet. Pull the trays out to allow them to dry slightly, or mix in more substrate to absorb excess moisture. Note: Saved corms may be more prone to rot.
There’s a little bit of mold on the corm, but the sprout looks healthy: This is generally okay! As long as the corm isn’t mushy, it’s still viable.
You’re seeing a lot of surface mold: Increase airflow. If your trays are stacked in a cooler without airflow, rotate them every few days to improve ventilation and disrupt mold growth.
Your corms aren’t sprouting but still look good: Check the substrate moisture level. If it’s too dry, use a spray bottle to lightly mist it—don’t soak it completely. If the moisture seems right, consider the location: it may be too cold for sprouting. Try moving them to a slightly warmer spot that maintains around 50°F.
Corms are sprouting more slowly than expected: If sprouting seems delayed, check for any temperature fluctuations or nearby drafts that could be slowing growth. Ranunculus and anemone corms need consistent conditions to sprout efficiently, so ensure the environment stays steady.
What to Do if You Have to Delay Planting Out the Ranunculus & Anemone Corms?
If you find yourself needing to delay planting due to weather, temperature, or life’s unexpected demands, don’t worry! It’s better to follow one of these options than to plant in the mud or during a cold snap.
Option 1: Greenhouse Staging
Place the sprouted corms in a greenhouse and start greening them up. This method works well, but be cautious—allowing them to get too comfortable in the greenhouse can lead to shock when they’re finally transplanted into the field or an unheated hoop house. If temperatures drop, leaves may get nipped by the cold, even after hardening off, but don’t stress! New growth will emerge to replace any lost foliage. Just make sure the greenhouse stays below 70°F to prevent overheating.
Option 2: Cold Storage
Store the sprouted corms in the coldest corner of your basement or at the bottom of a cooler, with no light. Keep temperatures around 38°F-40°F, with occasional dips as low as 37°F. This cold environment will slow down their growth, giving you a few weeks to delay planting.
Pro-Tip: Prepare the planting row in advance and cover it with a low tunnel when weather permits. This will keep the soil from freezing, ensure it’s ready for planting, and help it stay drier and warmer.
Wrapping Up: Ready to Try Pre-Sprouting?
Pre-sprouting ranunculus and anemone corms may feel like an extra step, but it can make a big difference in the health and success of your blooms. By taking a little time upfront to control for healthy growth, you’re setting your flowers up for a robust season—even in unpredictable weather.
If you’re new to these spring beauties or have struggled to grow them successfully, I hope this guide has given you the confidence to try pre-sprouting. This simple process can help your ranunculus and anemones thrive. Happy growing, and may your fields be filled with beautiful blooms this season!
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We are looking forward to sharing more blooms with you soon.
Jessica & Graham
